AGREEMENT AND PLAN OF MERGER AND EXCHANGE

                                  BY AND AMONG

                       ADVANCED TECHNOLOGY MATERIALS, INC.

                              ATMI HOLDINGS, INC.,

                               ALAMO MERGER, INC.

               ADVANCED DELIVERY & CHEMICAL SYSTEMS NEVADA, INC.,

               ADVANCED DELIVERY & CHEMICAL SYSTEMS HOLDINGS, LLC,

              ADVANCED DELIVERY & CHEMICAL SYSTEMS OPERATING, LLC,

               ADVANCED DELIVERY & CHEMICAL SYSTEMS MANAGER, INC.,

                                       AND

                   ADVANCED DELIVERY & CHEMICAL SYSTEMS, LTD.

                            DATED AS OF APRIL 7, 1997






                    AGREEMENT AND PLAN OF MERGER AND EXCHANGE

                                TABLE OF CONTENTS





           
 TABLE OF CONTENTS.....................................................
 INDEX OF SCHEDULES AND EXHIBITS.......................................
 INDEX OF DEFINED TERMS................................................
 ARTICLE I    ATMI PLAN OF MERGER .....................................
     1.1       Surviving Corporation...................................
     1.2       Certificate of Incorporation............................
     1.3       By-laws.................................................
     1.4       Directors...............................................
     1.5       Officers................................................
     1.6       Effective Time of the Merger............................
     1.7       Additional Actions......................................
     1.8       Merger Consideration....................................
     1.9       Conversion of Shares....................................
     1.10      Exchange Agent..........................................
     1.11      Exchange of Certificates................................
     1.12      ATMI Stock Options; Warrants............................
     1.13      Closing of Stock Transfer Books.........................
 ARTICLE II    EXCHANGE................................................
     2.1       Exchange................................................
     2.2       Additional Actions......................................
     2.3       Exchange Consideration..................................
     2.4       Escrow..................................................
     2.5       Average Closing Price...................................
     2.6       Tax Treatment...........................................
     2.7       Accounting Treatment....................................
 ARTICLE III   REPRESENTATIONS AND WARRANTIES OF THE ADCS GROUP........
     3.1       Capitalization; Options, Warrants, Rights...............
     3.2       Ownership of Interests..................................
     3.3       Organization, Good Standing and Power...................
     3.4       Organizational Documents................................
     3.5       Authorizations..........................................
     3.6       ADCS Commitments........................................
     3.7       Restrictions; Burdensome Agreements.....................
     3.8       Condition of the Assets.................................
     3.9       Title; Absence of Liens and Encumbrances, Etc...........
     3.10      Government and Other Consents...........................
     3.11      Franchises, Permits, Licenses; Compliance with Applica-
               ble Laws and Court Orders...............................
     3.12      Financial Statements ...................................
     3.13      Absence of Undisclosed Liabilities .....................
     3.14      Absence of Certain Changes..............................
     3.15      Indebtedness............................................
     3.16      Accounts Receivable.....................................
     3.17      Supplies................................................











           
     3.18      No Prebillings..........................................
     3.19      Taxes...................................................
     3.20      Facilities..............................................
     3.21      Insurance...............................................
     3.22      Books and Records.......................................
     3.23      Employees...............................................
     3.24      Employee Benefit Plans..................................
     3.25      Litigation..............................................
     3.26      Proprietary Rights......................................
     3.27      Section 341(f)(2) Consent...............................
     3.28      Related Party Transactions..............................
     3.29      Bank Accounts and Safe Deposit Arrangements.............
     3.30      Powers of Attorney......................................
     3.31      Environmental Matters; Health and Safety................
     3.32      Customers and Suppliers.................................
     3.33      Product and Service Warranties..........................
     3.34      Hart-Scott-Rodino.......................................
     3.35      Stock Ownership.........................................
     3.36      Finders' Fees...........................................
     3.37      Information in Disclosure Documents and Registration
               Statement...............................................
     3.38      Pooling.................................................
     3.39      Atlantic Coast Polymers, Inc............................
     3.40      No Misrepresentation....................................
 ARTICLE IV    REPRESENTATIONS AND WARRANTIES OF THE ATMI GROUP........
     4.1       Capitalization; Options, Warrants, Rights...............
     4.2       Organization; Good Standing; Power......................
     4.3       Organizational Documents................................
     4.4       Authorization...........................................
     4.5       SEC Compliance..........................................
     4.6       ATMI Commitments........................................
     4.7       Restrictions; Burdensome Agreements.....................
     4.8       Condition of the Assets.................................
     4.9       Title; Absence of Liens and Encumbrances, Etc...........
     4.10      Government and Other Consents...........................
     4.11      Franchises, Permits, Licenses; Compliance with Applica-
               ble Laws and Court Orders...............................
     4.12      Financial Statements....................................
     4.13      Absence of Undisclosed Liabilities......................
     4.14      Absence of Certain Changes..............................
     4.15      Indebtedness............................................
     4.16      Accounts Receivable.....................................
     4.17      Supplies................................................
     4.18      No Prebillings..........................................
     4.19      Taxes...................................................
     4.20      Employees...............................................
     4.21      Employee Benefit Plans..................................
     4.22      Litigation..............................................
     4.23      Proprietary Rights......................................
     4.24      Related Party Transactions..............................
     4.25      Environmental Matters; Health and Safety................
     4.26      Customers and Suppliers.................................












           
     4.27      Product and Service Warranties..........................
     4.28      No Prior Activities.....................................
     4.29      Hart-Scott-Rodino.......................................
     4.30      Finders' Fees...........................................
     4.31      Information in Disclosure Documents and Registration
               Statement...............................................
     4.32      Pooling.................................................
     4.33      Section 203 of the DGCL.................................
     4.34      No Misrepresentation....................................
 ARTICLE V     COVENANTS...............................................
     5.1       Access to Information...................................
     5.2       Interim Operations of ADCS Group........................
     5.3       Interim Operation of ATMI Group.........................
     5.4       Notices of Certain Events...............................
     5.5       Other Acquisitions by ATMI..............................
     5.6       No Public Disclosure....................................
     5.7       No Negotiation..........................................
     5.8       NovaMOS.................................................
     5.9       Election of Directors...................................
     5.10      HSR Act.................................................
     5.11      Preparation of S-4 and the Proxy Statement..............
     5.12      Best Efforts; Cooperation...............................
     5.13      ATMI Stockholder Matters................................
     5.14      Nasdaq Listing..........................................
     5.15      Affiliates..............................................
     5.16      Financial Statements and SEC Reports....................
     5.17      Employee Benefits.......................................
     5.18      Tax Matters.............................................
     5.19      Supplements to Disclosure Schedules.....................
     5.20      Expenses................................................
     5.21      Officer and Director Indemnity..........................
     5.22      Exchange Act Section 16(b)..............................
     5.23      Environmental Report....................................
 ARTICLE VI    CONDITIONS PRECEDENT TO CLOSING.........................
     6.1       Conditions to the Obligations of the ATMI Group.........
     6.2       Conditions to the Obligations of the ADCS Group.........
 ARTICLE VII   CLOSING.................................................
     7.1       Closing.................................................
     7.2       Simultaneous Closing....................................
 ARTICLE VIII  FURTHER ASSURANCES......................................
 ARTICLE IX    TERMINATION OF AGREEMENT................................
     9.1       Termination.............................................
     9.2       Termination Payment.....................................
     9.3       Failure to Deliver Interests............................
     9.4       Effect of Termination...................................
     9.5       Breach of Section 5.7...................................











           
 ARTICLE X     MISCELLANEOUS..............................................
    10.1       Right of Set-Off...........................................
    10.2       Benefits of this Agreement.................................
    10.3       Successors and Assigns.....................................
    10.4       Notices....................................................
    10.5       Severability...............................................
    10.6       Pooling....................................................
    10.7       Entire Agreement; Amendment................................
    10.8       Waiver.....................................................
    10.9       Applicable Law.............................................
    10.10      Jurisdiction...............................................
    10.11      Counterparts...............................................
    10.12      Knowledge .................................................







                         INDEX OF SCHEDULES AND EXHIBITS

                                    SCHEDULES


                       
 Schedule A               Holders
 Schedule 1.4             Directors of Surviving Corporation
 Schedule 1.5             Officers of Surviving Corporation
 Schedule 2.3(a)          Exchange Consideration
 ADCS Disclosure Schedule
 ATMI Disclosure Schedule
 Schedule 5.2             Permitted Pre-Closing Activities of ADCS
 Schedule 5.3(p)          Permitted Employment Agreements by ATMI
 Schedule 5.8             Post-Closing Operations
 Schedule 6.2(g)          ATMI Assessment Opinion Patents

                                    EXHIBITS

 Exhibit A                Form of Certificate of Merger
 Exhibit B                Form of Assignment of Membership Interests
 Exhibit C                Form of Registration Rights Agreement
 Exhibit D-1              Form of Affiliates Agreement of ADCS
 Exhibit D-2              Form of Affiliates Agreement of ATMI
 Exhibit E                Form of Proprietary Information and Inventions
                          Agreement
 Exhibit F                Form of Employment Agreements
 Exhibit G                Form of Escrow Agreement
 Exhibit H                Form of Indemnification Agreement
 Exhibit I                Form of Certificate of Holder
 Exhibit J                Form of Opinion of Counsel to ADCS
 Exhibit K                Form of Opinion of Patent Counsel to ADCS
 Exhibit L                Form of Releases
 Exhibit M                Form of Opinion of Counsel to ATMI
 Exhibit N                Form of Opinion of Patent Counsel to ATMI (General)
 Exhibit O                Form of Assessment Opinion of Patent Counsel to ATMI






                             INDEX OF DEFINED TERMS

  The following  index of defined terms is provided for convenience of reference
only:



 TERM                                       LOCATION
 ----                                       --------
                                         
 ADCS Commitments                           Section 3.6(a)(i)
 ADCS Controlled Group                      Section 3.24(e)(i)
 ADCS Disclosure Schedule                   Introductory paragraph to Article
                                            III
 ADCS Financial Statements                  Section 3.12
 ADCS Group                                 Page A-9
 ADCS Group Employee Benefit Plans          Section 3.24(a)
 ADCS Group Securities                      Section 3.1
 ADCS Group Subsidiaries                    Section 3.1
 ADCS Holdings                              Page A-9
 ADCS LP                                    Page A-9
 ADCS Manager                               Page A-9
 ADCS Material Adverse Effect               Section 3.3(a)
 ADCS Nevada                                Page A-9
 ADCS Operating                             Page A-9
 ADCS Organizational Documents              Section 3.4
 ADCS Premises                              Section 3.20
 Additional Agreements                      Introductory paragraph to Article
                                            III
 Affiliates Agreements                      Section 5.15
 Agreement                                  Page A-9
 ATMI                                       Page A-9
 ATMI Commitments                           Section 4.6(a)(i)
 ATMI Common Stock                          Section 1.8
 ATMI Controlled Group                      Section 4.21(e)(i)
 ATMI Disclosure Schedule                   Introductory paragraph to Article
                                            IV
 ATMI Employee Benefit Plans                Section 4.21(a)
 ATMI Financial Statements                  Section 4.12
 ATMI Group                                 Page A-9
 ATMI Group Securities                      Section 4.1
 ATMI Group Subsidiaries                    Section 4.1
 ATMI Identified Proprietary Rights         Section 4.23(h)
 ATMI Material Adverse Effect               Section 4.2(a)
 ATMI Organizational Documents              Section 4.3
 ATMI Premises                              Section 4.25(b)
 ATMI SEC Documents                         Section 4.5
 Average Closing Price                      Section 2.5
 Balance Sheet Date                         Section 3.12
 Burdensome Condition                       Section 6.1(n)
 Capital Stock                              Recitals
 Certificate of Merger                      Section 1.6
 Closing                                    Section 7.1
 Closing Date                               Section 7.1
 Code                                       Recitals
 Commitments                                Section 3.6(a)(i)
 Coverage                                   Section 5.17
 Current ADCS Indemnitee                    Schedule 5.21
 DGCL                                       Section 1.1
 Demand Date                                Section 2.3(b)








 TERM                                       LOCATION
 ----                                       --------
                                         
 Effective Time                             Section 1.6
 Employment Agreement                       Section 6.1(f)(ii)
 Environmental Conditions                   Section 3.31(a)(i)
 Environmental Laws                         Section 3.31(a)(ii)
 ERISA                                      Section 3.24(b)
 Escrow Agreement                           Section 6.1(f)(iv)
 Exchange                                   Recitals
 Exchange Act                               Section 4.5
 Exchange Agent                             Section 1.10
 Exchange Consideration                     Section 2.3(a)
 Hazardous Materials                        Section 3.31(a)(iii)
 Holders                                    Recitals
 Holdings                                   Page A-9
 Holdings Common Stock                      Recitals
 HSR Act                                    Section 5.10
 Indemnification Agreement                  Section 6.1(f)(v)
 Interests                                  Recitals
 knowledge                                  Section 10.12
 Marks                                      Section 3.26(c)
 Material Environmental Condition           Section 5.23
 Membership Interests                       Recitals
 Merger                                     Recitals
 Newco                                      Page A-9
 Notice (environmental)                     Section 3.31(a)(iv)
 Organizational Chart                       Section 3.1
 Outstanding ATMI Options                   Section 1.12
 Outstanding ATMI Warrants                  Section 1.12
 PBGC                                       Section 3.24
 Permit(s)                                  Section 3.11
 Pro Rata Portion                           Section 2.3(a)
 Proposal                                   Section 3.6(a)(ii)
 Proprietary Information and Inventions
  Agreements                                Section 6.1(f)(i)
 Proprietary Rights                         Section 3.26(b)
 Proxy Statement                            Section 3.37
 Qualified Beneficiaries                    Section 5.17
 Registration Rights Agreement              Section 5.3(k)
 Release                                    Section 3.31(a)(v)
 Reorganization                             Recitals
 Returns                                    Section 3.19(a)
 S-4                                        Section 1.8
 SEC                                        Section 1.8
 Section 16(b) Liability                    Section 5.22
 Section 16(b) Matter                       Section 5.22
 Securities                                 Section 3.1
 Securities Act                             Section 1.8
 Site Remediation Measures                  Section 3.31(a)(vi)
 Successor Welfare Plans                    Section 5.17
 Surviving Corporation                      Section 1.1
 Tax or Taxes                               Section 3.19(a)
 Tax Opinion                                Section 6.1(j)






                          AGREEMENT AND PLAN OF MERGER
                                  AND EXCHANGE

     This  AGREEMENT AND PLAN OF MERGER AND EXCHANGE  ("Agreement")  is made and
entered into as of the 7th day of April, 1997, by and among ADVANCED  TECHNOLOGY
MATERIALS,  INC.,  a Delaware  corporation  ("ATMI"),  ATMI  HOLDINGS,  INC.,  a
Delaware  corporation and wholly-owned  subsidiary of ATMI  ("Holdings"),  ALAMO
MERGER,  INC., a Delaware  corporation and  wholly-owned  subsidiary of Holdings
("Newco"),   ADVANCED  DELIVERY  &  CHEMICAL  SYSTEMS  NEVADA,  INC.,  a  Nevada
corporation ("ADCS Nevada"), ADVANCED DELIVERY & CHEMICAL SYSTEMS MANAGER, INC.,
a Delaware  corporation  ("ADCS Manager"),  ADVANCED DELIVERY & CHEMICAL SYSTEMS
HOLDINGS, LLC, a Delaware limited liability company ("ADCS Holdings"),  ADVANCED
DELIVERY & CHEMICAL SYSTEMS OPERATING, LLC, a Delaware limited liability company
("ADCS  Operating")  and  ADVANCED  DELIVERY & CHEMICAL  SYSTEMS,  LTD., a Texas
limited partnership ("ADCS LP"). ATMI, Holdings and Newco are referred to herein
as the "ATMI Group." ADCS Nevada,  ADCS Manager,  ADCS Holdings,  ADCS Operating
and ADCS LP are  referred  to herein as the "ADCS  Group." As used  herein,  the
terms the "ATMI  Group" and the "ADCS  Group" shall refer to each member of such
group,  two or  more  members  of such  group,  and all  members  of such  group
collectively, unless the context requires otherwise.

                              W I T N E S S E T H:

          This Agreement is made with reference to the following facts.

     A. The persons listed on Schedule A hereto  (collectively,  the "Holders"),
are the record and  beneficial  owners of (i) all of the issued and  outstanding
shares of capital  stock of ADCS Nevada and ADCS Manager (the  "Capital  Stock")
and  (ii)together  with ADCS  Nevada,  all of the  membership  interests in ADCS
Holdings (the  "Membership  Interests," and together with the Capital Stock, the
"Interests").

     B. The ATMI Group desires to acquire the ADCS Group by acquiring all of the
Holders' Interests.

     C. The parties desire such transaction to be a tax-free  transaction  under
the  Internal  Revenue  Code of 1986,  as  amended  (the  "Code"),  and for such
transaction to be accounted for as a pooling of interests.

     D. In order to provide for the tax-free  treatment of such  transaction and
to account for such  transaction  as a pooling of  interests,  the parties  have
determined that such transaction must be effected in accordance with Section 351
of the Code,  pursuant to which (i) Newco will be merged with and into ATMI (the
"Merger") with the  stockholders  of ATMI receiving  shares in Holdings and (ii)
simultaneously  therewith the Holders will transfer their  Interests to Holdings
in exchange (the "Exchange" and together with the Merger, the  "Reorganization")
for shares of Holdings common stock, par value $.01 per share ("Holdings  Common
Stock"), all pursuant to the terms, conditions and provisions of this Agreement.

     E. The Board of Directors of ATMI, deeming it advisable and for the benefit
of its  stockholders,  has  unanimously  approved the  Reorganization,  upon and
subject to the terms, conditions and provisions set forth herein.

     NOW,  THEREFORE,  in  consideration  of  the  foregoing  premises  and  the
representations  and  warranties  and mutual  covenants  herein  contained,  the
parties hereto agree as follows:




                                    ARTICLE I

                               ATMI Plan of Merger

     1.1.  Surviving  Corporation.  In  accordance  with the  provisions of this
Agreement and at the Effective  Time (as  hereinafter  defined),  Newco shall be
merged  with and into ATMI,  with ATMI being the  surviving  corporation  in the
Merger (the  "Surviving  Corporation").  At the  Effective  Time,  the  separate
existence of Newco shall cease, and the Surviving Corporation shall continue its
corporate  existence  under the laws of the State of Delaware.  The Merger shall
have the effects set forth in Section 259 of the  Delaware  General  Corporation
Law (the "DGCL"). By virtue of the Merger, the Surviving Corporation will become
a wholly-owned subsidiary of Holdings.

     1.2. Certificate of Incorporation. The Certificate of Incorporation of ATMI
as in effect at the Effective Time shall be the Certificate of  Incorporation of
the Surviving  Corporation until thereafter amended in accordance with its terms
and the DGCL.  The  authorized  number and par value of shares of all classes of
capital  stock of ATMI  immediately  prior to the  Effective  Time  shall be the
authorized number and par value of shares of the classes of capital stock of the
Surviving Corporation from and after the Effective Time.

     1.3. By-Laws.  The By-Laws of ATMI as in effect at the Effective Time shall
be the By-Laws of the Surviving Corporation until thereafter amended as provided
by law.

     1.4.  Directors.  From and after the Effective  Time, the persons listed on
SCHEDULE  1.4 shall be the  directors  of the  Surviving  Corporation,  all such
directors to hold office until their respective  successors are duly elected and
qualified in the manner provided in the Certificate of Incorporation and By-Laws
of the Surviving Corporation, or as otherwise provided by law.

     1.5.  Officers.  From and after the Effective  Time,  the persons listed on
SCHEDULE  1.5  shall be the  officers  of the  Surviving  Corporation,  all such
officers to hold office until their  respective  successors are duly elected and
qualified in the manner provided in the Certificate of Incorporation  and ByLaws
of the Surviving Corporation, or as otherwise provided by law.

     1.6.  Effective  Time of the  Merger.  If all the  conditions  set forth in
Article VI have been  fulfilled or waived in accordance  with the terms thereof,
and this  Agreement has not been  terminated in accordance  with Article IX, the
ATMI Group shall cause a Certificate  of Merger in the form  attached  hereto as
Exhibit A (the "Certificate of Merger") to be properly executed and filed on the
Closing Date (as hereinafter defined),  with the Secretary of State of the State
of Delaware.  The Merger shall become  effective  upon the filing of an executed
Certificate  of Merger and any and all required  related  certificates  with the
Secretary  of State of the State of Delaware  (the date and time when the Merger
becomes effective is referred to as the "Effective Time").

     1.7.  Additional  Actions.  If, at any time after the Effective  Time,  the
Surviving  Corporation  shall  consider or be advised  that any deeds,  bills of
sale,  assignments,  assurances  or any other  acts or things are  necessary  or
desirable to vest, perfect or confirm, of record or otherwise,  in the Surviving
Corporation, its right, title or interest in or to any of the rights, properties
or assets of Newco or ATMI  acquired  or to be  acquired  by reason  of, or as a
result of, the Merger, or otherwise to carry out the purposes of this Agreement,
the  Surviving  Corporation  and its  proper  officers  and  directors  shall be
authorized to execute and deliver,  in the name and on behalf of Newco and ATMI,
all such deeds, bills of sale, assignments and assurances and to do, in the name
and on behalf of Newco or ATMI,  all such  other acts and  things  necessary  or
desirable to vest,  perfect or confirm any and all right,  title or interest in,
to or under such rights,  properties or assets in the Surviving  Corporation  or
otherwise to carry out the purposes of this Agreement.

     1.8. Merger Consideration.  Each share of ATMI common stock, par value $.01
per share ("ATMI Common  Stock")  issued and  outstanding  on the Effective Time
shall be converted into the right to receive one (1) validly issued,  fully paid
and  non-assessable  share of  Holdings  Common  Stock,  such shares of Holdings
Common Stock to be issued in  accordance  with the terms of this  Agreement  and
pursuant to a registration





     statement on Form S-4 (the "S-4")  declared  effective under the Securities
Act of 1933, as amended (the  "Securities  Act"), by the Securities and Exchange
Commission (the "SEC").

  1.9. Conversion of Shares.

     (a) At the  Effective  Time,  each share of ATMI  Common  Stock  issued and
outstanding  immediately  prior to the  Effective  Time shall,  by virtue of the
Merger and without any action on the part of the holder  thereof,  automatically
be converted  into and  represent  the right to receive one (1) validly  issued,
fully paid and non-assessable share of Holdings Common Stock.

     (b) At the Effective  Time,  each share of ATMI Common Stock held in ATMI's
treasury immediately prior to the Effective Time shall, by virtue of the Merger,
be canceled and returned to the status of authorized but unissued  capital stock
of ATMI without payment of any consideration therefor.

     (c) At the Effective Time,  each share of common stock,  par value $.01 per
share, of Newco issued and outstanding  immediately  prior to the Effective Time
shall,  by virtue of the Merger and without any action on the part of the holder
thereof,  automatically  be converted into and represent one (1) validly issued,
fully paid and  non-assessable  share of common stock, par value $.01 per share,
of the  Surviving  Corporation,  as such shares of common stock are  constituted
immediately following the Effective Time.

     (d) At the Effective Time,  each share of common stock,  par value $.01 per
share,  of Holdings issued and  outstanding  immediately  prior to the Effective
Time  shall,  by virtue of the Merger and  without any action on the part of the
holder thereof, automatically be canceled.

     1.10. Exchange Agent. Boston EquiServe Limited  Partnership,  or such other
national or state bank as is selected  by  Holdings,  shall act as the agent for
ATMI stockholders for purposes of mailing and receiving  transmittal letters and
distributing  consideration  to holders  of ATMI  Common  Stock  (the  "Exchange
Agent").

  1.11. Exchange of Certificates.

     (a) As promptly as practicable after the Effective Time, the Exchange Agent
shall mail or deliver to each holder of record of a certificate or  certificates
which immediately prior to the Effective Time represented  outstanding shares of
ATMI Common Stock whose shares were converted into the right to receive Holdings
Common Stock pursuant to Section 1.9 hereof and the Certificate of Merger, (i) a
letter of transmittal (which shall specify that delivery shall be effected,  and
risk, loss and title to such certificates  shall pass, only upon delivery of the
certificates to the Exchange Agent and shall be in such form and have such other
provisions as Holdings may reasonably  specify) and (ii) instructions for use in
effecting  the  surrender of such  certificates  in exchange  for a  certificate
representing  Holdings  Common  Stock.  Upon  surrender  of  a  certificate  for
cancellation  to the  Exchange  Agent or to such other agent or agents as may be
appointed by Holdings, together with such letter of transmittal,  duly executed,
such agent shall promptly deliver in accordance with the  instructions  properly
contained in such letter of  transmittal a certificate  for the number of shares
of Holdings  Common  Stock to which such holder is entitled  pursuant to Section
1.9.

     (b) At the Effective  Time,  each holder of an  outstanding  certificate or
certificates for shares of ATMI Common Stock shall cease to have any rights as a
stockholder  of  ATMI.  Each  such  holder  of  an  outstanding  certificate  or
certificates  for shares of ATMI Common  Stock  converted  in the  Merger,  upon
surrender of each such certificate to the Exchange Agent, shall receive promptly
in exchange  for each such  certificate  the shares of Holdings  Common Stock to
which such holder is entitled pursuant to Section 1.9 of this Agreement. Pending
such  surrender and exchange,  such holder's  certificate  or  certificates  for
shares of ATMI  Common  Stock  shall be deemed for all  corporate  purposes,  by
virtue of the Merger and without  any action on the part of the holder  thereof,
to  evidence  only the right to receive  the  shares of  Holdings  Common  Stock
provided  for under  this  Agreement.  Unless  and  until  any such  outstanding
certificates  for  shares  of ATMI  Common  Stock  shall be so  surrendered,  no
dividend  (cash or stock)  payable to  holders  of record of shares of  Holdings
Common Stock as of





     any date  subsequent to the  Effective  Time shall be paid to the holder of
any such  outstanding  certificate,  but upon such surrender of such outstanding
certificate  there  shall be paid to the record  holder of the  certificate  for
shares of  Holdings  Common  Stock  issued in  exchange  therefor  the amount of
dividends,  if any,  without  interest  and less any  taxes  which may have been
imposed thereon, that have theretofore become payable with respect to the number
of those shares of Holdings Common Stock represented by such certificate  issued
upon such surrender and exchange.

     1.12.  ATMI Stock  Options;  Warrants.  At or prior to the Effective  Time,
Holdings, ATMI and Newco shall take all action necessary to cause the assumption
by Holdings  as of the  Effective  Time of the  options to purchase  ATMI Common
Stock  outstanding as of the Effective Time (the "Outstanding ATMI Options") and
warrants to purchase ATMI Common Stock outstanding as of the Effective Time (the
"Outstanding  ATMI  Warrants").  Each of the  Outstanding  ATMI  Options and the
Outstanding  ATMI Warrants shall be converted  without any action on the part of
the holder  thereof  into an option or warrant,  as the case may be, to purchase
shares of  Holdings  Common  Stock as of the  Effective  Time.  The holder of an
Outstanding  ATMI Option or an  Outstanding  ATMI  Warrant  shall be entitled to
receive  upon the  exercise  thereof one (1) share of Holdings  Common Stock for
each share of ATMI Common Stock  subject to such  warrant or option,  determined
immediately  before the  Effective  Time.  The  exercise  price of each share of
Holdings Common Stock subject to an Outstanding ATMI Warrant or Outstanding ATMI
Option  shall be the  exercise  price  per share of ATMI  Common  at which  such
warrant or option is  exercisable  immediately  before the Effective  Time.  The
assumption and  substitution  of the  Outstanding  ATMI Warrants and Outstanding
ATMI Options as provided  herein shall not give the holders of such  warrants or
options  additional  benefits which they did not have  immediately  prior to the
Effective  Time or  relieve  the  holders  of any  obligations  or  restrictions
applicable to their warrants or options or the shares  obtainable  upon exercise
of the warrants or options. Holdings shall (i) reserve out of its authorized but
unissued  shares of Holdings Common Stock  sufficient  shares to provide for the
exercise of the Outstanding  ATMI Warrants and Outstanding ATMI Options and (ii)
use all reasonable efforts to register under the Securities Act, coincident with
the Effective Time,  those shares of Holdings Common Stock to be issued upon the
exercise of the Outstanding ATMI Options,  which  registration  shall be made on
such form as may be permitted under the Securities Act.

     1.13.  Closing of Stock  Transfer  Books.  The stock transfer books of ATMI
shall be  closed  at the  close of  business  on the  business  day  immediately
preceding  the  Effective  Time. In the event of a transfer of ownership of ATMI
Common Stock which is not registered in the transfer records of ATMI, the shares
of Holdings Common Stock and cash for fractional shares (if any) to be issued in
the  Merger  as  provided  herein  may  be  delivered  to a  transferee,  if the
certificate  representing  such ATMI Common  Stock is  presented to the Exchange
Agent,  accompanied  by all  documents  required  to  evidence  and effect  such
transfer and by payment of any applicable stock transfer taxes.

                                   ARTICLE II

                                    Exchange

     2.1.  Exchange.  The ADCS Group  hereby  agrees to use its best  efforts to
cause the Holders on the Closing Date and simultaneously  with the filing of the
Certificate  of Merger with the  Secretary  of State of the State of Delaware to
tender their  Interests in exchange for the number of shares of Holdings  Common
Stock  determined  in accordance  with Section 2.3 below.  The ADCS Group hereby
further  agrees to use its best efforts,  exercised in good faith,  to cause the
Holders to have present at the Closing the original  certificate or certificates
representing  all of the issued and outstanding  shares of capital stock of each
of ADCS Nevada and ADCS Manager and to cause the Holders and their  spouses,  if
their  signatures be required,  to execute  and/or deliver (as  appropriate)  to
Holdings (i) either each of the original share  certificates,  duly endorsed for
transfer  against  delivery  by  Holdings  of  the  Exchange  Consideration  (as
hereinafter  defined)  or, as  permitted by Section  2.3(c)  below,  irrevocable
instructions  to the  Exchange  Agent to issue that number of shares of Holdings
Common Stock to each  respective  Holder as  determined  pursuant to Section 2.3
below,  with all requisite  transfer stamps,  if any are due,  attached thereto,
(ii) an assignment of the  Membership  Interests,  the form of which is attached
hereto as





     EXHIBIT B, and (iii) all such other deeds,  bills of sale,  assignments and
assurances  which  Holdings  deems  reasonably  necessary  or desirable to vest,
perfect or  confirm  any and all right,  title or  interest  in, to or under the
Interests.

     2.2.  Additional  Actions.  The ADCS  Group  hereby  agrees to use its best
efforts to cause the Holders and their  spouses,  if signatures be required,  to
execute  and deliver at the  Closing an  agreement  to the effect that if at any
time after the  Effective  Time Holdings  shall  consider or be advised that any
deeds,  bills of sale,  assignments,  assurances or any other acts or things are
necessary or desirable to vest, perfect or confirm,  of record or otherwise,  in
Holdings,  its right,  title or interest in or to any of the Holders'  Interests
acquired  or to be acquired  by reason of, or as a result of, the  Exchange,  or
otherwise to carry out the purposes of this Agreement, the Holders shall execute
and deliver all such deeds, bills of sale,  assignments and assurances and to do
all such  other acts and  things  reasonably  necessary  or  desirable  to vest,
perfect or  confirm  any and all right,  title or  interest  in, to or under the
Interests or otherwise to carry out the purposes of this Agreement.

     2.3.  Exchange  Consideration.  (a) In exchange  for the  Interests  of the
Holders and subject to the  provisions of Section  2.3(b) below,  at the Closing
Holdings  will issue to the Holders the  aggregate  number of shares of Holdings
Common Stock  (rounded up to the nearest  whole number of shares)  determined by
dividing Eighty-Seven Million Five Hundred Thousand Dollars ($87,500,000) by the
Average  Closing  Price (as  hereinafter  defined)  of ATMI  Common  Stock  (the
"Exchange  Consideration").  The  Exchange  Consideration  shall be deemed to be
allocated  to each Holder as  consideration  for the  exchange  of the  Holder's
Interests in the various ADCS Group entities,  as set forth on SCHEDULE  2.3(A),
according  to  the  Holders'  relative  pro  rata  ownership  percentage  of the
Interests  in such ADCS  Group  entity,  determined  by the  amount  which  each
Holder's  respective  ownership  bears to the aggregate  ownership of all of the
Holders  in  such  entity.  The  pro  rata  portion  of the  aggregate  Exchange
Consideration  allocated  to each  Holder is referred to herein as the "Pro Rata
Portion."

     (b) In the event  that the  combined  book  value of the ADCS Group and the
ADCS Group  Subsidiaries (as hereinafter  defined)  determined as of the Closing
Date in accordance with generally  accepted  accounting  principles is less than
$10,000,000 by an amount greater than $500,000, the number of shares of Holdings
Common  Stock to be issued in  accordance  with  Section  2.3(a)  above shall be
decreased by a number of shares equal to (1) $10,000,000 less (2) the book value
as of Closing,  divided by the Average Closing Price,  and the Holders shall, in
the manner provided below and in the Escrow  Agreement (as hereinafter  defined)
return any excess  shares of Holdings  Common Stock to  Holdings.  The shares of
Holdings Common Stock delivered into escrow pursuant to the Escrow Agreement (as
hereinafter  defined) shall stand as security for the Holders' obligations under
this Section 2.3(b). The determination of book value will be made by Holdings no
later than ninety (90) days after the Closing Date,  and written  notice thereof
shall  be  provided  to the  Holders  and the  escrow  agent  under  the  Escrow
Agreement.  Such written  notice shall indicate a date (the "Demand  Date"),  no
earlier  than ten (10)  business  days  after the date on which  such  notice is
received,  on or after which  Holdings may make demand upon the escrow agent for
such excess  shares.  If Holders  owning  seventy  percent  (70%) or more of the
Exchange  Consideration notify Holdings and the escrow agent in writing prior to
the Demand  Date that they do not agree with such book  value,  the Demand  Date
will be postponed  and such  Holders and  Holdings  will attempt to agree on the
book value within sixty (60) days after Holdings' determination thereof. If such
Holders and Holdings  are unable to agree,  then Ernst & Young LLP or such other
nationally  recognized  accounting  firm  acceptable to Holdings and the Holders
owning seventy  percent (70%) or more of the Exchange  Consideration  shall make
such determination  which shall be final and binding on all parties.  The escrow
agent is authorized to rely without investigation and to release to Holdings the
excess  shares  upon (i) a demand  made by  Holdings  after the  Demand  Date if
Holders owning seventy percent (70%) or more of the Exchange  Consideration have
not notified  the escrow  agent in writing of an  objection  prior to the Demand
Date,  (ii) a  written  determination  from  Ernst  & Young  LLP or  such  other
nationally  recognized  accounting firm, or (iii) any writing signed by Holdings
and  the  Holders  owning  seventy   percent  (70%)  or  more  of  the  Exchange
Consideration (each of (i), (ii) and (iii) shall constitute an Adjustment Notice
for purposes of Section 4(b) of the Escrow Agreement).





     (c) The Exchange  Consideration,  the amount and calculation of which shall
be set forth on a  certificate  executed by each of the parties at the  Closing,
will be  allocated  among the Holders  according  to their  respective  Pro Rata
Portions. Share certificates evidencing the Exchange Consideration shall be

     delivered to the Holders at the Closing, if at all practicable; and if not,
then   irrevocable   instructions   regarding   the  issuance  of  the  Exchange
Consideration to each of the Holders shall be delivered to the Exchange Agent at
Closing with the  certificates  representing  the Exchange  Consideration  to be
delivered as soon as practicable  thereafter.  No fractional  shares of Holdings
Common Stock shall be issuable by Holdings to any Holder in connection  with the
Exchange. In lieu of any such fractional shares, each Holder who would otherwise
have been  entitled to receive a fraction of a share of  Holdings  Common  Stock
shall be  entitled to receive  instead an amount in cash equal to such  fraction
multiplied by the Average Closing Price.

     2.4.  Escrow.  At the Effective Time,  Holdings shall deliver to the escrow
agent or any successor escrow agent appointed  pursuant to the Escrow Agreement,
certificates  evidencing  750,000  shares of the  Exchange  Consideration,  such
shares to be allocated among the Holders in accordance with their respective Pro
Rata Portions and to be held and applied in accordance with the  Indemnification
Agreement and the Escrow  Agreement.  Subject to the  restrictions  set forth in
Section 5.3, if between the date hereof and the Effective  Time,  the issued and
outstanding  shares  of ATMI  Common  Stock  shall  have been  combined,  split,
reclassified  or  otherwise  changed  into a  different  number  of  shares or a
different class of shares, an appropriate  adjustment to the number of shares of
Holdings Common Stock to be delivered into escrow shall be made.

     2.5. Average Closing Price. The term "Average Closing Price" shall mean the
average closing price of ATMI Common Stock on The Nasdaq National Market for the
twenty (20) trading days ended five (5) days prior to the date of ATMI's meeting
of stockholders  to approve the Merger;  provided that (i) in the event that the
Average  Closing Price is greater than $16 per share,  the Average Closing Price
shall be deemed to be $16 per  share;  and (ii) in the  event  that the  Average
Closing  Price is less than $14 per share,  the Average  Closing  Price shall be
deemed to be $14 per share.

     2.6. Tax Treatment.  The parties intend and expect that (i) the Merger will
qualify as a  reorganization  within the meaning of Section 368 of the Code in a
transaction  which is described in Section 351 of the Code,  and (ii) that, as a
result of the simultaneous closing of the Merger and Exchange,  the Holders will
be  treated  as having  exchanged  their  Interests  in a  transaction  which is
described in Section 351 of the Code.

     2.7.  Accounting  Treatment.   The  parties  intend  and  expect  that  the
Reorganization shall be accounted for as a pooling of interests.

                                   ARTICLE III

                        Representations and Warranties of
                                 the ADCS Group

     The ADCS Group hereby  jointly and  severally  represent and warrant to the
ATMI Group that,  except as set forth in the ADCS DISCLOSURE  SCHEDULE  attached
hereto  (which  ADCS  Disclosure   Schedule  makes  explicit  reference  to  the
particular  subsection as to which exception is taken,  which in each case shall
constitute the sole subsection as to which such exception  shall apply,  and the
statements   in  such   ADCS   Disclosure   Schedule   shall  be  deemed  to  be
representations and warranties),  as supplemented  pursuant to Section 5.19, and
acknowledge and confirm that the ATMI Group is relying upon such representations
and  warranties in connection  with the execution,  delivery and  performance of
this Agreement and the Additional  Agreements to which the ATMI Group is a party
described  in  Section  6.1(f)  below  (the  "Additional  Agreements")  and  the
completion of the Reorganization,  notwithstanding any investigation made by the
ATMI Group or on its behalf:

     3.1. Capitalization; Options, Warrants, Rights. SCHEDULE 3.1 sets forth the
aggregate number of all of the shares of any class of stock, other securities or
other  ownership  interests  (such types of  securities  are herein  referred to
collectively  as  "Securities"),  including the Capital Stock and the Membership
Interests, which the





     ADCS Group and each ADCS Group  Subsidiary  (as  hereinafter  defined)  are
authorized to issue (the "ADCS Group  Securities"),  the aggregate number of all
of the  ADCS  Group  Securities  issued  and  outstanding  and  the  record  and
beneficial  owners of all of the issued and outstanding  ADCS Group  Securities.
All Securities of the ADCS Group have been validly authorized and issued and are
fully paid and  non-assessable,  and have not been  issued in  violation  of any
preemptive, first refusal or other subscription rights of any holder of any ADCS
Group  Securities or any other person,  and have been issued in compliance  with
applicable  foreign,  federal  and state  securities  laws.  The  Capital  Stock
constitutes  all of the issued and  outstanding  shares of capital stock of ADCS
Nevada and ADCS  Manager.  Except as set forth on SCHEDULE  3.1, the  Membership
Interests  constitute  all of the membership  interests of ADCS  Holdings.  With
respect  to the  ADCS  Group  and  each  ADCS  Group  Subsidiary,  there  are no
outstanding  or existing (i) proxies,  voting  trusts,  or other  agreements  or
understandings  with  respect to the voting of the ADCS Group  Securities,  (ii)
ADCS Group  Securities  convertible  into or  exchangeable  for other ADCS Group
Securities, (iii) options, warrants or other rights to purchase or subscribe for
ADCS Group  Securities  (other  than this  Agreement)  or ADCS Group  Securities
convertible  into or  exchangeable  for other  ADCS  Group  Securities,  or (iv)
agreements  of any kind  relating  to the  issuance  or  purchase  of ADCS Group
Securities or ADCS Group  Securities  convertible into or exchangeable for other
ADCS Group  Securities.  No member of the ADCS Group holds or owns,  directly or
indirectly,  any  Securities  of any  other  corporation,  or has any  direct or
indirect equity or ownership  interest in any  association,  partnership,  joint
venture or other  entity other than (i) through  mutual  funds or other  similar
investment  vehicles  over which no  investment  discretion  is  retained,  (ii)
publicly-traded  Securities having a market value of $25,000 or less per issuer,
(iii)  ADCS  Group  Securities  and (iv) as  identified  on  SCHEDULE  3.1 (each
corporation,  association,  partnership,  joint venture or other entity in which
any member of the ADCS Group owns, directly or indirectly,  twenty percent (20%)
or more of the issued and  outstanding  Securities are referred to herein as the
"ADCS Group Subsidiaries"). A true and correct organizational chart for the ADCS
Group  and the ADCS  Group  Subsidiaries,  indicating  ownership  interests,  is
attached hereto as part of SCHEDULE 3.1 (the "Organizational Chart").

     3.2.  Ownership of Interests.  (a) A current list of the record  holders of
the Capital  Stock and the  Membership  Interests is set forth on SCHEDULE  3.1.
Each of such record holders is the record and beneficial  owner of the number of
ADCS Group Securities shown on SCHEDULE 3.1, and such ADCS Group Securities are,
to the ADCS Group's knowledge,  free and clear of all liens,  pledges,  security
interests, charges, claims and other encumbrances, and will be so free and clear
as of the Closing.

     (b) Each of the ADCS Group is the record and beneficial owner of the number
of ADCS Group Securities shown on the  Organizational  Chart,  free and clear of
all liens, pledges, security interests, charges, claims and other encumbrances.

     3.3.  Organization,  Good  Standing and Power.  (a) Each member of the ADCS
Group,  each  ADCS  Group  Subsidiary  and each  Holder  which is an entity is a
corporation,  limited  partnership or limited liability company, as the case may
be, duly organized,  validly existing and in good standing under the laws of its
state or country of  organization,  is  authorized  to do  business as a foreign
corporation,  foreign limited  partnership or foreign limited liability company,
as the case may be, in the  jurisdictions  set forth on SCHEDULE  3.3 and is not
required  to be  authorized  to do business  as a foreign  corporation,  foreign
limited partnership or foreign limited liability company, as the case may be, in
any other  jurisdiction  (within or without the United  States) by reason of the
nature of the business  now being  conducted  by it or the  properties  owned or
leased or operated by it in which the  failure to be so  qualified  would have a
material  adverse  effect on the  assets,  liabilities,  results of  operations,
financial   condition  or  business  of  the  ADCS  Group  and  the  ADCS  Group
Subsidiaries taken as a whole (an "ADCS Material Adverse Effect").

     (b) The ADCS Group,  each ADCS Group Subsidiary and each Holder which is an
entity have the  requisite  power,  corporate or  otherwise,  to own,  lease and
operate its properties and carry on its business as it is now being conducted by
it, and has the power and authority, corporate or otherwise, to execute, deliver
and perform this Agreement and the Additional  Agreements to which it is a party
and consummate the transactions contemplated hereby and thereby.






     (c) The ADCS Group and each ADCS Group  Subsidiary  conducts  its  business
under the trade names and other assumed names set forth on Schedule 3.3.

     3.4.  Organizational  Documents.  With respect to the ADCS Group, each ADCS
Group  Subsidiary  and each  Holder  which is an  entity,  the  ADCS  Group  has
heretofore  made  available to the ATMI Group a complete and correct copy of (i)
each corporation's Certificate or Articles of Incorporation, as amended to date,
(ii)  each  corporation's  By-Laws,  as  amended  to date,  (iii)  each  limited
liability company's Articles of Organization or similar  instrument,  as amended
to date, (iv) each limited liability  company's  Operating  Agreement or similar
agreement, as amended to date, and (v) each limited partnership's certificate of
limited partnership and Limited Partnership  Agreement,  each as amended to date
(items (i)  through  (v) being  referred  to herein as the "ADCS  Organizational
Documents"). Each of the foregoing are in full force and effect, and none of the
ADCS  Group,  any ADCS  Group  Subsidiary,  any  Holder  or to the ADCS  Group's
knowledge, any other party to the ADCS Organizational Documents, is in violation
of any of the provisions thereof.  There are no proceedings for the amendment or
modification of or any other change in the ADCS Organizational Documents.  There
are no proceedings  for the  dissolution  or liquidation of the ADCS Group,  any
ADCS Group  Subsidiary  or any Holder  which is an entity or, to its  knowledge,
threatening  the existence of the ADCS Group,  any ADCS Group  Subsidiary or any
Holder which is an entity.  The ADCS Group has made  available to the ATMI Group
the minute  books and stock  records  of each  member of the ADCS Group and each
ADCS Group Subsidiary.

     3.5.  Authorizations.  The ADCS Group has taken all  action,  corporate  or
otherwise,  necessary to authorize the  execution,  delivery and  performance of
this Agreement and, as  applicable,  the Additional  Agreements to which it is a
party.  Such  execution,  delivery and  performance  and the other  transactions
contemplated  hereby  do not  and  will  not  violate,  result  in any  default,
acceleration  or loss of any material  benefit under,  permit any third party to
rescind  any term or  provision  of, or  conflict  with any  terms of,  the ADCS
Organizational Documents, any law, lien, order, award, judgment,  decree, Permit
(as hereinafter  defined),  or any material agreements or contracts to which the
ADCS Group,  any ADCS Group Subsidiary or any Holder is a party or is subject or
by which the ADCS Group, any ADCS Group Subsidiary or any Holder or their assets
is bound or result in the creation of any lien,  charge or encumbrance  upon any
of the assets,  real,  personal or mixed,  tangible or  intangible,  of the ADCS
Group,  any ADCS Group  Subsidiary or any Holder or upon the Interests.  Each of
this Agreement and the Additional  Agreements to which the ADCS Group is a party
when  executed  will  constitute  its  legal,  valid  and  binding   obligation,
enforceable  against  it in  accordance  with its terms,  subject to  applicable
bankruptcy, insolvency, fraudulent transfer and other similar laws affecting the
enforceability of creditors' rights generally.

  3.6. ADCS Commitments.

     (a) Definitions. The following definitions shall apply for purposes of this
Section 3.6:

     (i) "ADCS  Commitments"  means all of the current  written or oral  leases,
agreements,  contracts,  instruments,  indentures,  notes  and  other  documents
("Commitments")  to which the ADCS Group or any ADCS Group Subsidiary is a party
other than the ADCS Group Employee Benefit Plans (as hereinafter  defined).  Not
included in the definition of ADCS Commitments are discussions,  negotiations or
Proposals  (as  defined  below)  between  ADCS Group  representatives  and third
parties.

     (ii)  "Proposal"  means  all of  the  current  written  offers,  quotes  or
proposals  presented  by the  ADCS  Group or any ADCS  Group  Subsidiary,  which
written offer,  quote, or proposal has not yet: (1) expired,  (2) been rejected,
or (3) resulted in the execution of an ADCS Commitment.

     (b) Schedule of ADCS  Commitments  and Proposals.  SCHEDULE 3.6 hereto sets
forth a list of the following:

     (i) any ADCS  Commitments  creating or  evidencing  rights to purchase ADCS
Group Securities;

     (ii) any ADCS Commitments among stockholders,  members,  partners, or other
persons or entities  holding  ADCS Group  Securities  with  respect to such ADCS
Group Securities;






     (iii) any ADCS  Commitments,  not including  purchase  orders placed by any
member of the ADCS  Group,  creating  or  evidencing  indebtedness  in excess of
$50,000.00 for money borrowed by the ADCS Group or any ADCS Group Subsidiary;

     (iv) any ADCS Commitments  mortgaging,  pledging,  granting,  or creating a
lien or security  interest or other encumbrance on any real or personal property
of the ADCS Group or any ADCS Group Subsidiary;

     (v) any ADCS  Commitments  creating or evidencing  any guaranty by the ADCS
Group or any ADCS Group  Subsidiary of payment or performance by any other party
involving in excess of $50,000.00;

     (vi) any ADCS  Commitments  pursuant  to which  the ADCS  Group or any ADCS
Group Subsidiary  reasonably  expects to receive aggregate payments in excess of
$250,000 in calendar year 1997;

     (vii) any ADCS Commitments with any dealer, sales representative, broker or
other distributor, jobber, advertiser or sales agency;

     (viii) any ADCS  Commitments  involving an  obligation  to pay in excess of
$100,000.00  to or from the ADCS  Group or any  ADCS  Group  Subsidiary  for the
furnishing or purchase of machinery, equipment, goods or services;

     (ix) any ADCS Commitments  (including private placement brochures) relating
to the future sale or repurchase of ADCS Group Securities;

     (x) any ADCS  Commitments  to register  under the  Securities  Act any ADCS
Group Securities;

     (xi) any ADCS  Commitments  involving  a sharing of  profits  or  expenses,
including, but not limited to, any joint venture agreements;

     (xii) any ADCS  Commitments  limiting  the freedom of the ADCS Group or any
ADCS Group Subsidiary to engage in any line of business;

     (xiii) any ADCS  Commitments  limiting the freedom of the ADCS Group or any
ADCS Group Subsidiary to operate in any geographic area;

     (xiv) any ADCS  Commitments  limiting  the freedom of the ADCS Group or any
ADCS Group Subsidiary to compete with any party;

     (xv) any ADCS  Commitments  limiting  the  freedom of the ADCS Group or any
ADCS  Group  Subsidiary  to  disclose  or use any  information  material  to the
operation of the business of the ADCS Group or any ADCS Group Subsidiary;

     (xvi) any collective bargaining agreements;

     (xvii) any ADCS Commitments  containing any unpaid severance liabilities or
obligations involving in excess of $5,000.00;

     (xviii) any fidelity or surety bond or completion  bond involving in excess
of $10,000.00;

     (xix) any ADCS  Commitments  relating  to  capital  expenditures  involving
future obligations in excess of $100,000.00;

     (xx) any ADCS Commitments for construction of physical facilities involving
in excess of $100,000.00;

     (xxi)  any  ADCS  Commitments  providing  for  disposition  of any  line of
business, material assets or ADCS Group Securities;

     (xxii)  any  ADCS  Commitments  providing  for  acquisition  of any line of
business,  material assets or Securities of any other business, which Securities
have a fair market value in excess of $50,000;

     (xxiii)  any  ADCS  Commitments   providing  for  merger  or  consolidation
(including letters of intent) with any other business;





     (xxiv)  any ADCS  Commitments  pertaining  to  maintenance  or  support  of
products, services or supplies; and

     (xxv) any  Proposals to enter into any future ADCS  Commitments  which,  if
currently in effect would be described  under this Section  3.6(b)(i),  (b)(ii),
(b)(ix),  (b)(xi),  (b)(xii),   (b)(xiii),   (b)(xiv),  (b)(xxi),  (b)(xxii)  or
(b)(xxiii)  as an ADCS  Commitment  or  which  involve  transactions  not in the
ordinary course of business.

     (c) The ADCS  Group and each ADCS Group  Subsidiary  have  complied  in all
material  respects  with and are not in material  default  under any of the ADCS
Commitments.

     (d)  Neither  the ADCS Group nor any ADCS Group  Subsidiary  has granted or
been granted any waiver or forbearance  with respect to any ADCS Commitment with
any customer or with any lender that in either case is in excess of $50,000.00.

     (e)  Neither  the ADCS Group nor any ADCS Group  Subsidiary  has granted or
been granted any waiver or forbearance  with respect to any ADCS  Commitments to
provide goods or services to customers that produced  aggregate  payments in the
year ending  December 31, 1996 of at least  $250,000.00 to the ADCS Group or any
ADCS Group Subsidiary.

     (f) The ADCS  Commitments  listed on Schedule 3.6 are valid and are in full
force and effect as to the ADCS Group or an ADCS Group  Subsidiary,  as the case
may be (and, to the knowledge of the ADCS Group, the other parties thereto).

     (g) Except as otherwise  noted and reserved  against in the ADCS  Financial
Statements (as  hereinafter  defined),  none of the ADCS  Commitments  listed on
Schedule 3.6 could reasonably be expected to result in the successful  assertion
or claim of any  material  liability  against  the ADCS  Group or any ADCS Group
Subsidiary in excess of that anticipated by the ADCS Commitment.

     (h) To the  ADCS  Group's  knowledge,  no  event  has  occurred,  or  could
reasonably be expected to occur,  that (after notice and lapse of time, or both)
would  become  a  breach  or  default  under  any ADCS  Commitment  (other  than
termination as the result of the  expiration,  absent a default,  of the term of
the ADCS Commitment).

     (i) True copies of all written ADCS  Commitments  and  reasonably  accurate
descriptions of all oral ADCS Commitments,  including any amendments thereto and
modifications thereof, have been made available to the ATMI Group.

     3.7. Restrictions;  Burdensome Agreements. None of the ADCS Group, any ADCS
Group  Subsidiary  or any  Holder  is a party  to any  contract,  commitment  or
agreement (including the ADCS Commitments), and none of the ADCS Group, any ADCS
Group Subsidiary or any Holder or any of their respective  properties and assets
is subject to or bound or affected by any charter,  by-law, operating agreement,
limited  partnership  agreement,  or other  organizational  restriction,  or any
order, judgment, decree, law, statute,  ordinance,  rule, regulation,  Permit or
other  restriction  of any kind or  character,  which would (i) prevent the ADCS
Group from entering into this Agreement and the  Additional  Agreements to which
it is a party or  prevent  the ADCS Group or any Holder  from  consummating  the
transactions  contemplated  hereby and  thereby,  or (ii) have an ADCS  Material
Adverse Effect and has not been disclosed in a Schedule hereto.

     3.8.  Condition  of the Assets.  Except as would not have an ADCS  Material
Adverse  Effect,  the  tangible  assets of the ADCS  Group  and each ADCS  Group
Subsidiary, including real, personal and mixed, material to the operation of its
business are in good condition and repair,  ordinary wear and tear excepted, and
suitable for the uses intended. The assets of the ADCS Group and each ADCS Group
Subsidiary  are  operated  in  conformity  in all  material  respects  with  all
applicable laws, ordinances, regulations, orders, Permits and other requirements
relating thereto adopted or currently in effect.  Schedule 3.8 sets forth a list
of each asset (other than  intangible  assets  listed on Schedule 3.26 and other
than as set forth on  Schedule  3.20)  having a book value in excess of $50,000,
indicating  whether  each such asset is owned or leased by the ADCS Group or any
ADCS Group





     Subsidiary,  and setting forth where each such asset is located.  Since the
Balance Sheet Date (as hereinafter defined), neither the ADCS Group nor any ADCS
Group  Subsidiary has,  except in the ordinary  course of business,  acquired or
sold or otherwise  disposed of any of its assets.  Schedule 3.8 also  includes a
list of each  lease  under  which the ADCS  Group or any ADCS  Group  Subsidiary
leases an asset (other than leased real  property)  having  replacement  cost of
$50,000 or more. The leases and other agreements or instruments  under which the
ADCS Group or any ADCS Group Subsidiary holds, leases,  subleases or is entitled
to the use of any of the assets having a replacement cost of $50,000 or more are
in full force and effect,  and all rentals,  royalties or other payments payable
thereunder have been duly paid or provided for by adequate reserves.  No default
or event of default by the ADCS Group or any ADCS Group Subsidiary  exists,  and
no event which, with notice or lapse of time or both, would constitute a default
by the ADCS Group or any ADCS Group Subsidiary,  has occurred and is continuing,
under terms or provisions,  express or implied, of any lease, agreement or other
instrument or under the terms or provisions of any agreement to which any of its
assets is subject which leases,  agreements or other instruments individually or
in the aggregate  involve assets having a book value of $50,000 or more, nor has
the ADCS Group or any ADCS Group Subsidiary received notice of any claim of such
default.

     3.9. Title; Absence of Liens and Encumbrances, Etc. Each member of the ADCS
Group and each ADCS Group  Subsidiary has good,  valid,  and marketable title to
its assets, free and clear of all mortgages,  security interests, claims, liens,
charges, title defects,  encumbrances,  restrictions on use or transfer or other
defects.  Except for Securities representing an interest in a member of the ADCS
Group or an ADCS  Group  Subsidiary  and  except  as set forth on  Schedule  3.9
hereto,  ADCS LP has good,  valid and  marketable  title to all of the  tangible
assets owned by the ADCS Group.

     3.10. Government and Other Consents. No consent,  authorization or approval
of,  exemption by, or filing with any  governmental,  public or  self-regulatory
body or authority or other party is required in connection  with the  execution,
delivery and  performance  by the ADCS Group of this  Agreement,  the Additional
Agreements  to  which  it is a party  or any of the  instruments  or  agreements
required  to be  executed  and  delivered  pursuant  to  this  Agreement  or any
Additional  Agreement,  or the  consummation  of the Exchange,  except under any
applicable  federal and state  securities  laws and the HSR Act (as  hereinafter
defined).

     3.11. Franchises,  Permits,  Licenses;  Compliance with Applicable Laws and
Court Orders.  Except for intellectual property matters covered by Section 3.26,
the ADCS Group and each ADCS Group  Subsidiary  have all  requisite  franchises,
permits,   licenses,   authorizations,   variances,   orders  and  approvals  of
governmental  or  administrative  authorities  (each a "Permit" and together the
"Permits")  necessary to own,  lease or operate its  properties or necessary for
the conduct of its business as currently conducted, other than those the absence
of which would not result in an ADCS Material  Adverse Effect.  All such Permits
are in full  force  and  effect,  and there is no  condition,  nor has any event
occurred, which constitutes or with the giving of notice, or passage of time, or
both,  would  constitute  a  violation  of the terms of any  Permit,  and to the
knowledge of the ADCS Group,  no  suspension or  cancellation  of any of them is
pending or threatened. Neither the execution of this Agreement or the Additional
Agreements to which any of the ADCS Group is a party nor the consummation of the
transactions  contemplated hereby or thereby would constitute a violation of the
terms of any such  Permit or grounds  for the  termination  of any such  Permit.
Schedule 3.11  contains a complete list of all such Permits and any  outstanding
applications for Permits to which the ADCS Group or any ADCS Group Subsidiary is
a party.  No application for a Permit filed by or on behalf of the ADCS Group or
any ADCS Group Subsidiary, or in connection with a facility operated by the ADCS
Group or any ADCS  Group  Subsidiary,  within  the last  five (5) years has been
denied,  other than the denial of Permits which individually or in the aggregate
did not or does not have an ADCS  Material  Adverse  Effect.  The ADCS Group and
each ADCS Group Subsidiary have, in the operation of its business, duly complied
with all applicable  laws,  rules,  regulations,  Permits and orders of federal,
state, local and foreign governments, except where the failure to comply did not
or does not have an ADCS Material Adverse Effect. Neither the ADCS Group nor any
ADCS Group Subsidiary is in default,  and no event has occurred that with notice
or the passage of time or both would constitute such a default,  with respect to
any order, judgment, writ, injunction, decree, award, Permit, rule or regulation
of any court,  governmental or regulatory body or arbitrator  which restrains or
limits in any material respect the operation of the business of, or





     the use of the assets of, the ADCS Group and ADCS Group  Subsidiaries taken
as a whole. To the knowledge of the ADCS Group, no officer,  director, member or
partner of the ADCS Group would be unable to give the  representation  that none
of the events or  circumstances  described in Rule 262 of Regulation A under the
Securities Act have occurred.

     3.12. Financial  Statements.  The ADCS Group has made available to the ATMI
Group  financial  information  respecting  the  ADCS  Group,  a copy of which is
annexed hereto as Schedule 3.12, as follows:  (i) audited  consolidated  balance
sheet at March 31, 1996 and audited combined balance sheet at December 31, 1996,
and (ii) audited  consolidated  financial  statements  of the ADCS Group for the
year ended March 31, 1996,  and audited  combined  financial  statements for the
nine (9)  months  ended  December  31,  1996 (the  "Balance  Sheet  Date")  (the
financial statements referred to in clauses (i) and (ii) collectively called the
"ADCS Financial  Statements").  The ADCS Financial Statements fairly present the
financial  position and results of  operations of the ADCS Group for the periods
then ended and the financial  position of the ADCS Group at the dates thereof in
accordance  with generally  accepted  accounting  principles  (subject to normal
year-end  adjustments for unaudited interim financial  statements,  if any). The
ADCS Group and each ADCS Group Subsidiary has maintained its books of account in
accordance with applicable laws, rules and regulations of government authorities
and with generally accepted accounting principles consistently applied, and such
books of  account  are and,  during the  period  covered  by the ADCS  Financial
Statements  were,  correct and  complete in all  material  respects,  fairly and
accurately reflect or reflected the income, expenses,  assets and liabilities of
the ADCS Group,  including the nature thereof and the  transactions  giving rise
thereto,  and provide or provided a fair and accurate basis for the  preparation
of the ADCS Financial Statements.

     3.13.  Absence of Undisclosed  Liabilities.  Neither the ADCS Group nor any
ADCS Group  Subsidiary has any  liabilities  or  obligations,  either  absolute,
accrued,  contingent or otherwise,  which individually or in the aggregate would
have an ADCS Material  Adverse Effect,  and which (i) have not been reflected in
the ADCS Financial Statements, (ii) have not been described in this Agreement or
in any of the Schedules  hereto,  or (iii) have been incurred  since the Balance
Sheet Date other than in the  ordinary  course of its business  consistent  with
past practices.

     3.14.  Absence of Certain  Changes.  Since the Balance Sheet Date there has
not been, except as described in Schedule 3.14 hereto:

     (a) any  material  adverse  change in the  business,  financial  condition,
assets or liabilities, results of operations, or prospects of the ADCS Group and
the ADCS Group  Subsidiaries taken as a whole other than changes in the ordinary
course of business, which changes have not in the aggregate been, and do not, to
the ADCS  Group's  knowledge,  threaten  to  become,  materially  adverse to the
business, financial condition, assets or liabilities,  results of operations, or
prospects of the ADCS Group and the ADCS Group Subsidiaries taken as a whole;

     (b) any damage,  destruction  or loss in excess of $25,000  (whether or not
covered by insurance)  adversely  affecting any of the assets or business of the
ADCS Group or any ADCS Group Subsidiary;

     (c) any ADCS  Commitment  or liability  undertaken  or incurred by the ADCS
Group or any ADCS Group Subsidiary  (whether  absolute,  accrued,  contingent or
otherwise and whether due or to become due), or any transaction  entered into by
the ADCS Group or any ADCS Group  Subsidiary which is material to the ADCS Group
and the ADCS Group  Subsidiaries  taken as a whole, other than items incurred or
entered  into in the  ordinary  course  of  business  and  consistent  with past
practices of the ADCS Group or any ADCS Group Subsidiary;

     (d) any payment,  discharge or satisfaction of any claim, lien, encumbrance
or liability of the ADCS Group or any ADCS Group Subsidiary outside the ordinary
course of business in excess of $5,000 individually or $50,000 in the aggregate;





     (e) any sale, transfer,  conveyance,  assignment,  lease, license,  pledge,
mortgage or other disposition or encumbrance by the ADCS Group or any ADCS Group
Subsidiary of any asset of the ADCS Group or any ADCS Group Subsidiary  having a
value more than $20,000 individually or $50,000 in the aggregate,  except in the
ordinary course of business and consistent with past practices of the ADCS Group
or any ADCS Group Subsidiary;

     (f) any modification,  amendment,  cancellation,  termination,  revocation,
rescission,  or waiver of any  rights  with  value to the ADCS Group or any ADCS
Group Subsidiary in excess of $20,000 pursuant to any ADCS Commitments;

     (g) any material change in the accounting  methods or practices followed by
the ADCS Group or any ADCS Group Subsidiary or any change in the depreciation or
amortization policies or rates theretofore adopted and applied;

     (h) any (i) grant of any  severance  or  termination  pay to any  director,
officer,  employee,  partner  or  member  of the ADCS  Group  or any ADCS  Group
Subsidiary  in  excess  of  $25,000,  (ii)  entering  into  of  any  employment,
severance,  management,  consulting,  deferred  compensation  or  other  similar
agreement (or any amendment to any such existing  agreement)  with any director,
officer,  employee,  partner  or  member  of the ADCS  Group  or any ADCS  Group
Subsidiary, except for employment agreements entered into in the ordinary course
of business (which agreements do not involve any Holder or which individually or
in the  aggregate  are not  material to the  financial  condition  or results of
operations of the ADCS Group and the ADCS Group  Subsidiaries taken as a whole),
(iii) change in benefits  payable under existing  severance or  termination  pay
policies or  employment,  severance,  management,  consulting  or other  similar
agreements,   other  than  normal   yearly   adjustments,   or  (iv)  change  in
compensation,  bonus  or  other  benefits  payable  to  any  director,  officer,
employee,  partner  or member of the ADCS  Group or any ADCS  Group  Subsidiary,
other than normal yearly  adjustments,  and other than any increase  pursuant to
any ADCS Group Employee  Benefit Plan, the formulae or commission rates of which
have not been amended or changed;

     (i)  declared,  paid or set aside for payment by the ADCS Group or any ADCS
Group  Subsidiary  any dividend or other  distribution  in respect of ADCS Group
Securities, or redeemed, purchased or otherwise acquired any of their respective
ADCS Group Securities;

     (j) issued,  authorized  for  issuance,  or entered into any  commitment to
issue any Security, bond, note or other debt obligation of the ADCS Group or any
ADCS Group Subsidiary;

     (k) any transaction or payments between (i) any Holder or any related party
or  entity  and (ii) the ADCS  Group  or any ADCS  Group  Subsidiary  not in the
ordinary course of business;

     (l) the  termination,  whether  voluntary or  involuntary,  of any material
employee  of the ADCS  Group or any ADCS  Group  Subsidiary  or of any  material
relationship  between  the  ADCS  Group  or  any  ADCS  Group  Subsidiary  and a
consultant; or

     (m) any  agreement or  understanding  entered into by the ADCS Group or any
ADCS Group Subsidiary  whether in writing or otherwise,  for the ADCS Group, any
ADCS Group Subsidiary or, to the ADCS Group's knowledge,  any Holder to take any
of the actions specified in this Section 3.14.

     3.15.  Indebtedness.  Neither the ADCS Group nor any ADCS Group  Subsidiary
has any  obligation  for money borrowed or under any guarantee nor any agreement
or  arrangement to borrow money or to enter into any such  guarantee,  and as of
the Closing Date, neither the ADCS Group nor any ADCS Group Subsidiary will have
any  obligation  for money  borrowed nor any agreement or  arrangement to borrow
money,  and neither the ADCS Group nor any ADCS Group  Subsidiary  will have any
guarantee  outstanding  nor any  agreement or  commitment to enter into any such
guarantee.





     3.16. Accounts Receivable.  No amounts in excess of $10,000 individually or
$50,000 in the aggregate  included in the accounts  receivable of the ADCS Group
or any ADCS Group Subsidiary in the ADCS Financial Statements have been released
or are, or are  currently  expected to be,  regarded  under  generally  accepted
accounting  principles as unrecoverable in whole or in part except to the extent
there shall have been an appropriate bad debt reserve therefor. Such receivables
are not,  to the  knowledge  of the ADCS  Group,  subject  to any  counterclaim,
refusal to pay or setoff not  reflected  in the  reserves  set forth on the ADCS
Financial  Statements.  Schedule  3.16 hereto sets forth a list of all  accounts
receivable  of the ADCS  Group or any ADCS Group  Subsidiary  as of the close of
business  on the  Balance  Sheet  Date,  none  of  which,  to the  ADCS  Group's
knowledge,  is owing from a debtor that has become  bankrupt or insolvent or has
been pledged to any third party.

     3.17.  Supplies.  The  supplies  of the  ADCS  Group  and  the  ADCS  Group
Subsidiaries  taken as a whole  consist  of a  quality  and  quantity  generally
adequate for and usable in the ordinary course of business  consistent with past
practice.

     3.18. No Prebillings.  Neither the ADCS Group nor any ADCS Group Subsidiary
has  prebilled  or  received  payment,  and the ADCS  Group  and the ADCS  Group
Subsidiaries  will not prebill or receive payment,  from any of its accounts for
goods to be  delivered  or for  services to be  rendered  or for  expenses to be
incurred  subsequent  to the  Closing  Date,  except in the  ordinary  course of
business and consistent  with past practices of the ADCS Group or any ADCS Group
Subsidiary.

  3.19. Taxes.

     (a) All  returns,  reports,  information  statements,  and  other  forms or
documentation (the "Returns") related to Taxes (as hereinafter defined) required
to be filed or  maintained  on or before the  Closing  Date with  respect to the
business,  activities or assets of the ADCS Group or any ADCS Group  Subsidiary,
have been filed or  maintained,  or will be filed or maintained on or before the
Closing Date, in accordance  with all applicable laws (after taking into account
extensions  duly  obtained),  and no penalties or other charges are due or could
reasonably  be  expected  to become due with  respect to the late  filing of any
Return.  All  Returns  are or will be  accurate  and  complete  in all  material
respects and properly reflect the Taxes due for the periods covered thereby. All
Taxes due and payable,  whether or not called for by the Returns,  and all Taxes
properly  allocable  to periods  ending on or before the Closing  Date have been
paid, adequately provided for in the ADCS Financial Statements or any ADCS Group
Subsidiary's  financial  statements,  or properly  protested or will be so paid,
reserved for or protested by the Closing Date,  and the ADCS Group and each ADCS
Group Subsidiary have maintained all required records with respect to Taxes. All
Taxes  required to be withheld or  collected by the ADCS Group or any ADCS Group
Subsidiary  have been duly  withheld or collected and have been paid over to the
appropriate  governmental  authorities,  or are held in separate  bank  accounts
established  exclusively for such purpose.  Except as set forth on Schedule 3.19
hereto,  no audit or investigation of any Return is pending or, to the knowledge
of the ADCS Group, threatened. Schedule 3.19 hereto sets forth the status of any
audit that is pending,  including the amounts of any  deficiencies and additions
to Tax indicated on any notices of proposed  deficiency or statutory  notices of
deficiency  that may have been issued in  connection  therewith  and all of such
deficiencies  or  additions  to Tax have been paid.  There are no  requests  for
rulings pending before any taxing authority. Schedule 3.19 sets forth the states
in which the ADCS Group or any ADCS Group  Subsidiary has filed Returns relating
to Taxes for the taxable  years ended March 31,  1994  through  March 31,  1996.
Neither the ADCS Group nor any ADCS Group  Subsidiary has executed or filed with
the Internal  Revenue Service or any other domestic or foreign taxing  authority
any agreement  extending  the period for  assessment or collection of any Taxes,
and neither the ADCS Group nor any ADCS Group  Subsidiary  has waived any law or
regulation fixing the period for assessment or collection of Taxes.  Neither the
ADCS Group nor any ADCS Group  Subsidiary  is a party to any  pending  action or
proceeding by any domestic or foreign  governmental  authority for assessment or
collection of Taxes, and no claim for assessment or collection of Taxes has been
asserted or threatened  against the ADCS Group or any ADCS Group  Subsidiary for
which  provision has not been made in the ADCS Financial  Statements or any ADCS
Group Subsidiary's financial statements.  There are no tax liens upon any of the
properties or assets of the ADCS Group or any ADCS Group  Subsidiary  other than
liens for Taxes not yet due and payable. True and complete





     copies of the  income  tax  returns  of the ADCS  Group and each ADCS Group
Subsidiary  for the three (3) fiscal years ended in 1994 through  1996, as filed
with the  Internal  Revenue  Service and all other  domestic  or foreign  taxing
authorities, have previously been made available to the ATMI Group.

     As used herein,  "Taxes" (or "Tax" where the context  requires)  shall mean
all federal,  state, county, local, foreign and other taxes (including,  without
limitation,  income,  profits,  premium,  estimated,  excise, stamp, sales, use,
occupancy,  gross  receipts,  franchise,  ad valorem,  value  added,  severance,
capital levy,  production,  transfer,  gains,  withholding,  employment,  social
security, workers' compensation, unemployment compensation,  payroll-related and
property   taxes  (real  and  personal),   imposts,   custom  duties  and  other
governmental  charges and assessments of whatever kind), whether or not measured
in  whole  or in part  by net  income,  and  including  deficiencies,  interest,
additions to tax or interest or penalties with respect thereto.

     (b) No sales,  use or other transfer or conveyance taxes are or will become
payable  by the ADCS  Group or the ATMI  Group  solely as a  consequence  of the
Exchange, other than taxes based upon the net income of the parties.

     3.20. Facilities. SCHEDULE 3.20 hereto sets forth a list of all of the real
property and all of the  buildings,  warehouses  and storage  facilities  owned,
leased or  operated  by the ADCS Group or any ADCS Group  Subsidiary  during the
last five (5) years (the "ADCS  Premises"),  indicating  where such  property or
facility is located,  whether such property is owned,  leased,  occupied  and/or
operated  by the  ADCS  Group  or any  ADCS  Group  Subsidiary  and the  date of
acquisition or occupancy thereof. The leases and other agreements or instruments
under  which  the  ADCS  Group  or any  ADCS  Group  Subsidiary  holds,  leases,
subleases,  occupies or is entitled to the use of the ADCS  Premises are in full
force  and  effect,  and  all  rentals,  royalties  or  other  payments  payable
thereunder prior to the date hereof have been duly paid.  Neither the ADCS Group
nor any ADCS Group  Subsidiary  is in default in any  material  respect,  and no
event  has  occurred  that  with  notice or the  passage  of time or both  would
constitute  such a  default,  with  respect  to any such  leases  and other such
agreements or  instruments.  The current use by the ADCS Group or any ADCS Group
Subsidiary  and, to the knowledge of the ADCS Group,  by any third party, of the
ADCS Premises  complies in all material respects with all applicable zoning laws
and  building  and use  restrictions.  Neither the ADCS Group nor any ADCS Group
Subsidiary has received a notice of violation of any applicable law,  ordinance,
regulation,  order,  Permit or requirement  (other than Environmental Laws which
are addressed in Section 3.31)  relating to its operations or the ADCS Premises,
nor has the ADCS  Group or any ADCS  Group  Subsidiary  failed  to comply in any
material respect with any provision or condition of any such lease, agreement or
other instrument with respect to the ADCS Premises.  All buildings,  plants, and
structures  owned by the ADCS  Group or any ADCS  Group  Subsidiary  lie  wholly
within the  boundaries of the real property owned by it and do not encroach upon
the property of, or otherwise  materially  conflict with the property rights of,
any other person.

     3.21.  Insurance.  Schedule  3.21  sets  forth  a list of the  policies  of
insurance  and fidelity or surety  bonds  carried by the ADCS Group and the ADCS
Group  Subsidiaries.  Neither the ADCS Group nor any ADCS Group  Subsidiary  has
failed to present or to give any notice with respect to any material claim under
any insurance policy in due and timely fashion,  and all insurance  premiums due
and payable by the ADCS Group or any ADCS Group  Subsidiary in  connection  with
the policies  set forth on Schedule  3.21 prior to the Closing Date have been or
will be paid. There are no outstanding written  requirements or material written
recommendations  by any  insurance  company that issued a policy with respect to
any of the properties and assets of the ADCS Group or any ADCS Group Subsidiary,
by any Board of Fire Underwriters or other body exercising  similar functions or
by any  governmental  authority  requiring or recommending  any repairs or other
work to be done on or with  respect to any of the  properties  and assets of the
ADCS  Group or any ADCS  Group  Subsidiary  or  requiring  or  recommending  any
equipment or  facilities  to be installed  on or in  connection  with any of the
assets.  The unemployment  insurance ratings and contributions of the ADCS Group
and each ADCS Group Subsidiary are also set forth on Schedule 3.21.

     3.22.  Books and  Records.  The books of account  and other  financial  and
corporate  records of the ADCS Group and each ADCS Group Subsidiary are complete
and accurate in all material respects and are maintained





     in accordance  with good business  practices.  The minute books of the ADCS
Group and each ADCS Group  Subsidiary as previously  made  available to the ATMI
Group and its counsel,  contain  accurate records of all meetings and accurately
reflect all other action of the  stockholders,  directors,  partners and members
(and committees thereof) of the ADCS Group and each ADCS Group Subsidiary.

     3.23. Employees.  SCHEDULE 3.23 contains a true and complete list of all of
the officers and directors,  partners and members of the ADCS Group and the ADCS
Group  Subsidiaries,  specifying  their office or title, and a true and complete
list of all the employees of the ADCS Group and each ADCS Group Subsidiary as of
the date hereof.  Neither the ADCS Group nor any ADCS Group  Subsidiary  has any
written or oral  contract of  employment  with any employee of the ADCS Group or
any ADCS  Group  Subsidiary,  and  neither  the ADCS  Group  nor any ADCS  Group
Subsidiary is a party to or subject to any collective  bargaining  agreement nor
has  been a party  to or  subject  to any  collective  bargaining  agreement  or
collective  bargaining  plan  during the last five (5) years.  Neither  the ADCS
Group nor any ADCS Group  Subsidiary  is a party to any pending nor, to the ADCS
Group's knowledge, threatened labor dispute affecting the ADCS Group or any ADCS
Group Subsidiary. The ADCS Group and each ADCS Group Subsidiary have complied in
all material  respects with all  applicable  foreign,  federal,  state and local
laws,  ordinances,  rules  and  regulations  and  requirements  relating  to the
employment  of labor,  including,  but not  limited to, the  provisions  thereof
relative  to  wages,  hours,  collective  bargaining,  drug  testing,  personnel
policies and practices, payment of Social Security, unemployment and withholding
taxes,  and ensuring  equality of opportunity  for employment and advancement of
minorities and women. To the knowledge of the ADCS Group, neither the ADCS Group
nor any ADCS Group Subsidiary is liable for any arrears of wages or any taxes or
penalties  for  failure to comply  with any of the  foregoing.  None of the ADCS
Group or any ADCS Group  Subsidiary has received notice from any employee listed
on Schedule 3.23 as earning an annual base salary in excess of $40,000 that such
employee is terminating  his or her  employment  with the ADCS Group or any ADCS
Group Subsidiary,  nor to the knowledge of the ADCS Group does any such employee
intend to terminate his or her employment  with the ADCS Group or any ADCS Group
Subsidiary.

  3.24. Employee Benefit Plans.

     (a) SCHEDULE 3.24 sets forth a list of every stock option,  stock purchase,
stock appreciation right, bonus,  incentive,  deferred or current  compensation,
excess  benefits,   profit  sharing,   pension,  thrift,  savings,   retirement,
severance, sickness, accident, medical, disability,  hospitalization,  vacation,
insurance or other plan or  agreement  which  provides  benefits to or for or on
behalf  of any one or  more  employees  of the  ADCS  Group  or any  ADCS  Group
Subsidiary  (including former employees) or their  beneficiaries  (collectively,
"ADCS Group Employee Benefit  Plans").  The ADCS Group has made available to the
ATMI Group true,  correct and complete copies of all ADCS Group Employee Benefit
Plans, as in effect on the date of this Agreement,  all written  descriptions or
summaries thereof, all trust agreements or other funding arrangements (including
insurance or group annuity contracts)  relating thereto,  all amendments thereto
and all  determination  letters  issued by the  Internal  Revenue  Service  with
respect to such ADCS Group Employee Benefit Plans.

     (b) No employee  benefit  plan  (within the meaning of Section  3(3) of the
Employee  Retirement  Income Security Act of 1974, as amended  ("ERISA")) exists
which  covers or is  maintained  for the benefit of any of the  employees of the
ADCS Group or any ADCS Group  Subsidiary  or to which the ADCS Group or any ADCS
Group  Subsidiary or any Holder is required to make  contributions on account of
any employees of the ADCS Group or any ADCS Group Subsidiary.

     (c) There are no  actions,  suits or claims  pending  (other  than  routine
claims for benefits) or, to the knowledge of the ADCS Group,  threatened against
any ADCS Group Employee  Benefit Plan,  nor, to the knowledge of the ADCS Group,
does any basis  therefor  exist.  Each ADCS Group  Employee  Benefit  Plan is in
compliance in all material  respects with all applicable  requirements  of ERISA
and the Code and their  regulations,  and other  applicable laws and regulations
and has been  administered in all material respects in accordance with its terms
and with applicable legal requirements.





  (d) With respect to each ADCS Group Employee Benefit Plan,

     (i) the ADCS Group and each ADCS Group  Subsidiary have performed or caused
to be performed all  obligations  required to be performed under such ADCS Group
Employee Benefit Plan (including, but not limited to, the making when due of all
contributions  required by the terms of such plan, by law, or by any  collective
bargaining agreement, or otherwise);

     (ii) the ADCS Group and each ADCS Group  Subsidiary have complied in timely
fashion  with the terms of each ADCS Group  Employee  Benefit  Plan and with all
requirements of all laws, rules and regulations (including,  but not limited to,
ERISA and the Code) which are  applicable  to each ADCS Group  Employee  Benefit
Plan and each ERISA Plan, including, but not limited to,

     (1)  the  filing  when  due of all  required  returns,  reports  and  other
documents, and

     (2) compliance with all rules concerning  notifications  and disclosures to
participants and beneficiaries under each such plan;

     (iii) neither the ADCS Group nor any ADCS Group  Subsidiary  has engaged in
any "prohibited  transaction"  within the meaning of Section 4975 of the Code or
Section 406 of ERISA nor has  committed  any breach of fiduciary  responsibility
under ERISA (or has any knowledge  that any other person has engaged in any such
prohibited  transaction  or committed  any such breach)  which could subject the
ATMI Group and/or the Surviving  Corporation to an excise tax or other liability
under ERISA or the Code; and

     (iv)  neither  the ADCS Group nor any ADCS Group  Subsidiary  is in default
under or in  violation  of (and has no  knowledge of any default or violation by
any other person of) the terms of any ADCS Group Employee Benefit Plan.

  (e) Except as set forth on SCHEDULE 3.24,

     (i) no employee  pension  benefit  plan (as  defined in Section  3(2)(A) of
ERISA) which is sponsored by any member of the "controlled group" (as defined in
Section  4001(a)(14)  of ERISA) which  includes  the ADCS Group,  any ADCS Group
Subsidiary or any Holder (the "ADCS Controlled Group") has been terminated since
September 2, 1974;

     (ii) no  proceeding  has been  initiated  to  terminate  any such  employee
pension benefit plan;

     (iii) there has been no  "reportable  event" (within the meaning of Section
4043(c) of ERISA) with respect to any such employee  pension benefit plan, other
than those with respect to which the  requirement  of thirty (30) days'  notice,
whether in advance of the event or following the event,  to the Pension  Benefit
Guaranty Corporation ("PBGC") has been waived by regulation;

     (iv) no excise or other  taxes  (or  interest  or  penalties  with  respect
thereto) are due or owing with respect to any such employee pension benefit plan
because of any failure to comply with the minimum funding  standards of ERISA or
for failing to comply with any other applicable  requirement  under ERISA or the
Code;

     (v) all  contributions  to any such employee pension benefit plan have been
made within the time provided by law;

     (vi) at no time  during  the last five (5) years has the ADCS  Group or any
ADCS Group  Subsidiary or any member of the ADCS  Controlled  Group been a party
to, or been required to make any  contribution  to, a  "Multiemployer  Plan" (as
defined  in Section  3(37) of  ERISA),  nor has the ADCS Group or any ADCS Group
Subsidiary or any member of the ADCS Controlled Group made a complete or partial
withdrawal  from a  Multiemployer  Plan as a  result  of  which  any  withdrawal
liability has been or will be incurred by any of them;

     (vii) neither the ADCS Group or any ADCS Group Subsidiary nor any member of
the ADCS Controlled  Group has incurred any liability to the PBGC other than for
the payment of annual  premiums (and no such premium  payments are currently due
and owing); and




     (viii)  neither the ADCS Group or any ADCS Group  Subsidiary nor any member
of the ADCS Controlled  Group has entered into any  transaction  within the past
five (5) years the  purpose  of which is to evade  liability  under  Title IV of
ERISA.

     (f) No ADCS  Group  Employee  Benefit  Plan  (other  than  one  which is an
employee  pension  benefit plan within the meaning of Section  3(2)(A) of ERISA)
provides  benefits  (including,  without  limitation,  death,  health or medical
benefits, whether or not insured) with respect to current or former employees of
the ADCS Group or any ADCS Group  Subsidiary  beyond their  retirement  or other
termination of service with the ADCS Group or any ADCS Group  Subsidiary,  other
than (i)  coverage  mandated  by  applicable  law,  (ii)  deferred  compensation
benefits  which have been accrued as  liabilities on the books of the ADCS Group
or any ADCS Group Subsidiary,  (iii) benefits the full cost of which is borne by
the current or former  employees (or their  beneficiaries),  (iv) benefits which
have already been satisfied in full or (v) death benefits under any pension plan
to the extent set forth in Schedule 3.24 hereto.

     3.25.  Litigation.  There is no action,  suit or proceeding  pending and of
which it has been served notice or, to the ADCS Group's  knowledge,  threatened,
by or against the ADCS Group, any ADCS Group Subsidiary, its respective business
or  assets,  or,  to the ADCS  Group's  knowledge,  any  Holder  relating  to or
affecting the Interests,  at law, in equity, by way of arbitration or before any
governmental  department,  commission,  board or  agency.  To the  ADCS  Group's
knowledge,  there are no existing facts or conditions  which reasonably would be
expected  to  give  rise  to  any  charge,  claim,  litigation,  proceeding,  or
investigation  by  any  third  party  which  could  reasonably  be  expected  to
materially  adversely  affect  its  business,  the ADCS  Group or any ADCS Group
Subsidiary,  nor are there any facts or  conditions  which could  reasonably  be
expected  to give  rise to any  order of  condemnation,  appropriation  or other
taking of any of the assets. There is no litigation, action, suit, investigation
or  proceeding  pending  and of which  it has  been  served  notice  or,  to the
knowledge  of the ADCS  Group,  threatened,  before any  court,  agency or other
governmental  body  against the ADCS  Group,  any ADCS Group  Subsidiary  or any
Holder (or any corporation or entity  affiliated  with the ADCS Group,  any ADCS
Group  Subsidiary  or any Holder) which seeks to enjoin or prohibit or otherwise
challenge the transactions contemplated hereby or contemplated by the Additional
Agreements. SCHEDULE 3.25 sets forth each action, suit or proceeding against the
ADCS Group, any ADCS Group Subsidiary, its respective business or assets, or any
Holder  relating to or affecting  the  Interests,  at law, in equity,  by way of
arbitration or before any governmental department,  commission, board or agency,
which has been dismissed or settled or in which a judgment has been rendered, in
each case within the past five (5) years, and the disposition  thereof. The ADCS
Group has made  available  to ATMI true and  correct  copies of each  settlement
agreement and release,  if any, in connection  with any matter  discussed in the
prior sentence,  each of which constitutes a legal, valid and binding obligation
of the  parties  thereto,  and no  party  thereto  is in  default  of any of its
obligations  thereunder.  There is no  order,  judgment,  decree  or  settlement
agreement  against or involving the ADCS Group, any ADCS Group Subsidiary or any
Holder involving any ongoing liabilities or restrictions which, in the case of a
Holder,  would  adversely  affect  the  ability of the  Holder to  transfer  the
Interests.

     3.26.  Proprietary Rights. (a) SCHEDULE 3.26 sets forth a true, correct and
complete  list of all  foreign  and  domestic  Marks (as  hereinafter  defined),
patents  and  applications   for  patents,   and  registered   copyrights,   and
applications  therefor,  owned by the ADCS Group or any ADCS Group Subsidiary or
in which the ADCS Group or any ADCS Group Subsidiary has any rights or licenses.
The ADCS Group has made  available to the ATMI Group copies of all agreements of
the ADCS Group or any ADCS  Group  Subsidiary  with each  officer,  employee  or
consultant  of the ADCS Group or any ADCS Group  Subsidiary  providing  the ADCS
Group or any ADCS Group Subsidiary with secrets and inventions developed or used
by the ADCS  Group or any  ADCS  Group  Subsidiary.  All of such  agreements  so
described are valid, enforceable and legally binding.

     (b) The ADCS  Group and each ADCS Group  Subsidiary  own or possess or have
the  right  to  obtain  licenses  or other  rights  to use all  patents,  patent
applications,   trade  secrets,  copyrights,   inventions,   drawings,  designs,
proprietary  know-how  or  information,  or other  rights with  respect  thereto
(collectively referred to as "Proprietary Rights"),  which it has determined are
used in its business, and it believes the same are sufficient






     to conduct its business as it has been and is now being conducted. The ADCS
Group is not aware of any  existing  Proprietary  Rights that the ADCS Group and
the ADCS Group  Subsidiaries  do not  already  own or possess or will be able to
obtain a license under, which Proprietary Rights would be necessary for the ADCS
Group or any ADCS Group Subsidiary to conduct its business.

     (c) To the ADCS Group's  knowledge,  the  operations  of the ADCS Group and
each ADCS Group Subsidiary do not conflict with or infringe upon, and no one has
asserted  to the ADCS Group or any ADCS Group  Subsidiary  that such  operations
conflict with or infringe upon, any Proprietary Rights or any trademarks,  trade
names,  or service  marks  (collectively  referred to as "Marks"),  Marks owned,
possessed or used by any third party.  There are no claims,  disputes,  actions,
proceedings,  suits or appeals  pending  against the ADCS Group,  any ADCS Group
Subsidiary or any Holder with respect to any  Proprietary  Rights or Marks,  and
none has been threatened against the ADCS Group or any ADCS Group Subsidiary. To
the ADCS  Group's  knowledge,  there are no facts or alleged  facts  which would
reasonably  serve as a basis for any claim that the ADCS Group or any ADCS Group
Subsidiary  does not have the  right to use,  free of any  rights  or  claims of
others, all Proprietary Rights and Marks in the development,  manufacture,  use,
sale or other  disposition  of any or all products or services  presently  being
used, furnished or sold in the conduct of its business as it has been and is now
being  conducted.  Neither  the ADCS  Group nor any ADCS  Group  Subsidiary  has
violated the terms of any confidentiality  agreement or nondisclosure  agreement
entered into in favor of any third party.

     (d) There are no inter parties  proceedings  before any patent or trademark
authority to which the ADCS Group or any ADCS Group Subsidiary is a party.

     (e) The ADCS  Group and each ADCS  Group  Subsidiary  have  taken all other
measures they deem reasonable to maintain the  confidentiality  of the processes
and formulae,  research and development results and other know-how, the value of
which  to the ADCS  Group  or any  ADCS  Group  Subsidiary  is  contingent  upon
maintenance of the confidentiality thereof.

     (f)  Each  employee  and  officer  of the  ADCS  Group  or any  ADCS  Group
Subsidiary is a party to a confidential  non-disclosure  agreement with the ADCS
Group or such ADCS Group  Subsidiary  (the form of which has been made available
to the ATMI Group).  No employee of the ADCS Group or any ADCS Group  Subsidiary
is in violation of any material  term of any  employment  contract,  proprietary
information and inventions agreement, confidentiality agreement, non-competition
agreement,  or any other contract or agreement  relating to the  relationship of
any such  employee  with the ADCS  Group or any ADCS  Group  Subsidiary,  or any
previous employer.

     (g) The Proprietary  Rights and Marks are free of any unresolved  ownership
disputes with respect to any third party. To the ADCS Group's knowledge there is
no unauthorized use, infringement or misappropriation of any of such Proprietary
Rights or Marks by any third party, including any employee or former employee of
the ADCS Group or any ADCS Group Subsidiary.

     (h) Other than as part of  transactions  identified in SCHEDULE  3.26,  the
ADCS Group has not  burdened  the  Proprietary  Rights with any liens,  security
interests, financing agreements, or other encumbrances.

     3.27. Section 341(f)(2) Consent.  At no time has the ADCS Group or any ADCS
Group Subsidiary,  or any predecessor,  consented under Section 341(f)(1) of the
Code, or agreed under Section  341(f)(3) of the Code, to have the  provisions of
Section 341(f)(2) of the Code apply to any sale of its capital stock.

     3.28. Related Party Transactions.  SCHEDULE 3.28 sets forth the amounts and
other  essential  terms of  indebtedness  or other  obligations,  liabilities or
commitments  (contingent  or  otherwise)  of the ADCS  Group  or any ADCS  Group
Subsidiary  to or from  any  Holder  or any  other  present  officer,  director,
partner, member or stockholder or any person related to, controlling, controlled
by or under common control with any of the foregoing  (other than for employment
services  performed within the past month the payment for which is not yet due),
and all other  transactions  between such persons and the ADCS Group or any ADCS
Group Subsidiary,





     except for transactions  which through  consolidation are eliminated in the
ADCS  Group  Financial  Statements.  Without  limiting  the  generality  of  the
foregoing,  as of the date  hereof,  none of the  Holders  or any other  present
officer,  director,  partner,  member or  stockholder  or any person related to,
controlling, controlled by or under common control with any of the foregoing (a)
has any material  direct or indirect  interest in any entity which does business
with the ADCS Group or any ADCS Group Subsidiary, (b) has any direct or indirect
interest in any property,  asset or right which is used by the ADCS Group or any
ADCS Group Subsidiary in the conduct of its business, or (c) has any contractual
relationship  with the ADCS Group or any ADCS Group  Subsidiary  other than such
relationships which occur from being an employee, officer, director, etc.

     3.29. Bank Accounts and Safe Deposit Arrangements. SCHEDULE 3.29 sets forth
a complete list of (i) the name and address of each bank and brokerage firm with
which the ADCS Group or any ADCS Group Subsidiary has any accounts, safe deposit
boxes,  lock boxes or vaults,  (ii) the account numbers  relating  thereto,  and
(iii) the names of all persons  authorized to deal with such accounts or to have
access to such boxes or vaults.

     3.30.  Powers of  Attorney.  No person has any power of  attorney to act on
behalf of the ADCS Group or any ADCS Group  Subsidiary in connection with any of
its properties or business  affairs other than such powers to so act as normally
pertain to the officers of such entity.

  3.31. Environmental Matters; Health and Safety.

     (a) Definitions. The following definitions shall apply for purposes of this
Section 3.31:

     (i)  "Environmental  Conditions" means  circumstances with respect to soil,
surface waters, groundwaters, stream sediment and air, both on-site and off-site
of the  real  property  either  owned or  leased  by a party or on which a party
operates or operated  its  business  during the last ten (10) years,  that could
require  remedial  action and/or that would  reasonably be expected to result in
claims and/or demands by and/or liabilities to third parties, including, but not
limited to governmental entities.

     (ii) "Environmental Laws" means any and all foreign,  federal, state, local
or municipal laws, regulations,  ordinances, rules, orders, guidelines, policies
or requirements of any governmental  authority  regulating or imposing standards
of  liability or standards of conduct  (including  common law)  concerning  air,
water,  solid waste,  Hazardous  Materials  (including,  but not limited to, the
transfer  of  facilities   involved  in  the  generation,   storage,   handling,
transportation  and/or  disposal of Hazardous  Materials),  worker and community
right-to-know,  hazard  communication,  noise,  radioactive  material,  resource
protection,  inland wetlands and watercourses and health  protection.  Such laws
include, but are not limited to, the Resource Conservation and Recovery Act, the
Comprehensive  Environmental  Response,  Compensation  and  Liability  Act,  the
Superfund Amendments and Reauthorization Act, the Occupational Safety and Health
Act, the Hazardous  Materials  Transportation  Act, the Toxic Substances Control
Act, the Federal Insecticide Fungicide and Rodenticide Act, the Clean Water Act,
the Clean Air Act, and the Safe Drinking Water Act, all as amended and effective
on the date hereof, and the regulations,  rules and orders promulgated or issued
thereunder.  Environmental  Laws also include any or all environmental  permits,
approvals, consents,  stipulations,  licenses,  registrations,  certificates and
authorizations  which are required by law,  ordinance or regulation  and any and
all environmental  regulatory  compliance  requirements  applicable to a party's
business  and/or a party or, to the party's  knowledge,  its  predecessor(s)  in
interest as of or prior to the Closing.

     (iii) "Hazardous Materials" means any petroleum,  petroleum products,  fuel
oil, explosives,  reactive materials,  ignitable materials, corrosive materials,
hazardous chemicals, hazardous wastes, hazardous substances, extremely hazardous
substances, toxic substances, toxic chemicals, radioactive materials, infectious
materials and any other element,  compound,  mixture, solution or substance that
may pose a present or potential hazard to human health or the environment, or as
otherwise defined in or regulated by Environmental Laws.





     (iv)  "Notice"  means  any  summons,  citation,  directive,  order,  claim,
litigation, pleading,  investigation,  proceeding, judgment, letter or any other
written or oral  communication (if such oral communication is made to a manager,
officer or employee  responsible for environmental  compliance matters) from the
United  States  Environmental   Protection  Agency,   California   Environmental
Protection Agency, Texas Natural Resources Conservation Commission,  Connecticut
Department of Environmental  Protection or any other foreign,  federal, state or
local agency or authority, or any other entity or any individual, concerning any
intentional or unintentional  act or omission that constitutes or may constitute
a violation of an Environmental  Law and shall expressly  include the imposition
of any lien pursuant to any Environmental Laws.

     (v)  "Release"  means  releasing,   spilling,  leaking,  pumping,  pouring,
emitting,  emptying,  discharging,   ejecting,  escaping,  leaching,  disposing,
seeping,  infiltrating,  draining or dumping.  This term shall be interpreted to
include both the present and past tense, as appropriate.

     (vi) "Site Remediation Measures" means any efforts of any foreign, federal,
state or local government,  or a party,  their contractors,  subcontractors,  or
agents,  that are made,  designed,  initiated,  or  maintained  as  required  by
Environmental  Laws or  Commitments  entered  into by a party in order to ensure
that  Environmental   Conditions  are  consistent  with  Environmental  Laws  or
Commitments  entered  into  by a  party,  including,  site  investigation,  site
monitoring, containment, clean-up, transport, removal, disposal, restoration and
other remedial efforts of any kind.

     (b) Environmental Representations and Warranties. Except as may be found to
the  contrary  in the Phase II  environmental  site  assessment  referred  to in
Section 5.23 below:

     (i) Compliance.  The ADCS Group and each ADCS Group  Subsidiary and, to the
ADCS Group's  knowledge,  its  predecessor(s) in interest,  have been and are in
compliance  with  and  have  no  liability  or  obligation   arising  under  any
Environmental  Law, and neither the ADCS Group nor any ADCS Group Subsidiary has
received  any  Notice  from  any  applicable  governmental  agency  seeking  any
information  or alleging  any  violation  of such  Environmental  Laws.  No Site
Remediation Measure is necessary or required under Environmental Law or any ADCS
Commitment  for  its  business  or  the  ADCS   Premises,   nor  are  there  any
Environmental   Conditions  on  the  ADCS  Premises.  No  capital  improvements,
alterations  or repairs to the ADCS  Premises are necessary or required to bring
such facility into compliance with all Environmental Laws now in effect.

     (ii) Hazardous  Materials/Underground  Tanks.  None of the ADCS Group,  any
ADCS Group  Subsidiary or any Holder and, to the ADCS Group's  knowledge,  their
predecessor(s)  in interest,  has caused or permitted any use of its business or
the ADCS Premises to generate,  manufacture,  refine,  transport,  treat, store,
handle, dispose,  transfer,  produce or process any Hazardous Materials or solid
waste,  except in compliance with all Environmental  Laws, and has not caused or
permitted  and has no knowledge of the Release of any such  Hazardous  Materials
on-site or off-site of the ADCS Premises, resulting, or that could in the future
result in an Environmental  Condition requiring Site Remediation  Measures.  The
ADCS  Premises and all principal  items and machinery and equipment  used in the
ADCS Group's  business comply with all applicable  Environmental  Laws. The ADCS
Premises do not contain any asbestos  requiring  removal now or in the course of
any remodeling that may occur in the future, or other Hazardous Materials,  and,
except for chemicals and raw materials used, and wastes  generated in connection
with,  the  manufacture  of the ADCS  Group's  products,  which in each case are
located  on the ADCS  Premises  in the  ordinary  course  of  business,  no such
materials are located on, in or under the ADCS Premises. Any and all underground
and  aboveground  tanks at the ADCS Premises are in compliance  with any and all
Environmental  Laws, and such  Environmental  Laws do not mandate the removal or
retrofitting of such tanks for a period of five (5) years after the Closing. The
removal  of any tank has been  carried  out in  compliance  with all  applicable
Environmental Laws.

     (iii)  There  are  no  outstanding  or,  to  the  ADCS  Group's  knowledge,
threatened  actions,  claims,  proceedings,  determinations  or judgments by any
party, including but not limited to any governmental





     authority,  whether foreign,  federal,  state, local or any agency thereof,
against or involving the ADCS Group, any ADCS Group Subsidiary or any Holder, or
to the ADCS Group's knowledge, against or involving the ADCS Group's or any ADCS
Group  Subsidiary's  predecessor(s)  in interest in any manner arising under the
Environmental  Laws or alleging or involving  personal injury or property damage
as a result of a  violation  of any  Environmental  Law or  otherwise  involving
Environmental Conditions. Attached hereto as SCHEDULE 3.31 is a list of all such
actions,  claims,  proceedings,  determinations  and judgments issued within the
past ten  (10)  years by any  party  against  the  ADCS  Group,  any ADCS  Group
Subsidiary  or any  Holder as it  relates  to the ADCS  Group or the ADCS  Group
Subsidiaries and, to the ADCS Group's  knowledge,  against any predecessor(s) in
interest.

     (iv) The ADCS Group and each ADCS Group Subsidiary and, to the ADCS Group's
knowledge,  their  predecessor(s)  in interest,  have  complied with all notice,
recordkeeping and reporting  requirements imposed by any governmental  authority
and any informational  requests or demands arising under any Environmental Laws.
None of the ADCS Group,  any ADCS Group  Subsidiary  or any Holder,  nor, to the
ADCS  Group's  knowledge,  the  ADCS  Group's  or any  ADCS  Group  Subsidiary's
predecessor(s) in interest,  is liable for any penalties,  fines, or forfeitures
or is subject to any  restrictions on the conduct of its business for failure to
comply with any of the foregoing.

     (v) Schedule 3.31 lists all of the ADCS  Premises,  the date of acquisition
or  leasing  thereof,  the  person or entity  from whom the ADCS  Premises  were
acquired or leased,  the operations  conducted  thereon and, to the ADCS Group's
knowledge, the operations conducted prior to the acquisition or leasing thereof.

     3.32.  Customers and Suppliers.  SCHEDULE 3.32 sets forth a list of (i) all
of the  customers of the ADCS Group or any ADCS Group  Subsidiary as of the date
hereof,  but not including  customers from whom the ADCS Group or any ADCS Group
Subsidiary in the  aggregate  has received less than $250,000 in gross  receipts
during the  immediately  preceding  twelve-month  period,  and (ii) the ten (10)
largest suppliers of the ADCS Group and the ADCS Group  Subsidiaries  taken as a
whole in terms of purchases made during the 1995 and 1996 fiscal years.  Neither
the ADCS Group nor any ADCS Group  Subsidiary has received any notice or has any
knowledge that any customer  listed for the 1996 fiscal year (1) has ceased,  or
currently  intends  to cease,  to use the  products,  goods or  services  of the
business  of  the  ADCS  Group  or  of  any  ADCS  Group  Subsidiary;   (2)  has
substantially  reduced, or currently intends to substantially reduce, the use of
products,  goods or  services  of the  business of the ADCS Group or of any ADCS
Group Subsidiary; or (3) other than in the ordinary course of business and to an
extent which is not reasonably  likely to have an ADCS Material  Adverse Effect,
has sought, or is seeking,  to reduce the price it will pay for products,  goods
or services of the  business of the ADCS Group or of any ADCS Group  Subsidiary.
Neither the ADCS Group nor any ADCS Group  Subsidiary has received any notice or
has any knowledge that any such supplier will not sell raw materials,  supplies,
merchandise  and other goods to the ADCS Group or any ADCS Group  Subsidiary  at
any time after the Closing Date on terms and conditions similar to those used in
the  current  sales to the  business,  subject to general  and  customary  price
increases and unforeseeable supply or demand changes.

     3.33. Product and Service Warranties. To the knowledge of the ADCS Group:

     (a) All products sold and all services  rendered by the ADCS Group and each
ADCS Group Subsidiary have been in conformity in all material  respects with all
applicable  ADCS  Commitments  and all  expressed  warranties,  and no  material
liability exists or will arise for replacement or damage in connection with such
sales or for  services  not  rendered in all  material  respects  in  accordance
therewith.

     (b)  There is  adequate  provision  in the ADCS  Financial  Statements  for
liabilities  and  obligations  for damaged,  defective or returned goods, or for
replacement  of goods or for  allowances  with respect to goods sold or services
rendered by or on behalf of the ADCS Group or any ADCS Group Subsidiary.

     (c) Neither the ADCS Group nor any ADCS Group Subsidiary has any pattern of
claims or actions based upon  allegations of the same or similar  product defect
for any of its products.





     (d) There has not been any  material  product  recall,  rework or  retrofit
relating to any line of product manufactured,  shipped or sold by the ADCS Group
or any ADCS Group  Subsidiary,  nor to the  knowledge of the ADCS Group is there
any basis for any such product recall, rework or retrofit.

     3.34.  Hart-Scott-Rodino.  The "total assets" and the "annual net sales" of
the  "ultimate  parent  entity"  (as such terms are used  within the  meaning of
Section  7A.(a)(2)(A) of the  Hart-Scott-Rodino  Antitrust  Improvements  Act of
1976) of the ADCS Group are less than $100,000,000.

     3.35.  Stock  Ownership.  Other than through  mutual funds or other similar
investment vehicles over which no investment discretion is retained, none of the
ADCS  Group,  any ADCS  Group  Subsidiary  or any  Holder  owns  any ATMI  Group
Securities  issued  by ATMI and has no  warrants,  options  or other  rights  to
purchase  or  otherwise  acquire  or  convert  any  obligations  into ATMI Group
Securities.

     3.36. Finders' Fees. There is no investment banker, broker, finder or other
intermediary  that has been retained by or is authorized to act on behalf of the
ADCS Group, any ADCS Group Subsidiary or any Holder who might be entitled to any
fee or commission  from the ATMI Group or any other person upon  consummation of
the transactions contemplated by this Agreement.

     3.37. Information in Disclosure Documents and Registration Statement.  None
of the information  made available or to be made available by the ADCS Group for
inclusion or  incorporation  by reference in (i) the S-4 will,  at the time such
registration  statement  becomes effective under the Securities Act, contain any
untrue  statement of a material fact or omit to state any material fact required
to be stated  therein or necessary to make the statements  therein,  in light of
the circumstances under which they are made, not misleading,  and (ii) the proxy
statement  relating  to  the  meeting  of  ATMI's  stockholders  to be  held  in
connection with the Merger (the "Proxy  Statement")  will, at the date mailed to
stockholders  and at the  time  of the  meeting  of  stockholders  to be held in
connection with the Merger,  contain any untrue  statement of a material fact or
omit to state any material  fact  required to be stated  therein or necessary in
order to make the statements  therein, in light of the circumstances under which
they are made, not misleading.

     3.38. Pooling. To its knowledge, the ADCS Group has not taken, or failed to
take, any action that would jeopardize the treatment of the  Reorganization as a
"pooling of interests" for accounting purposes.

     3.39.  Atlantic  Coast  Polymers,  Inc.  ADCS  Nevada  is  the  record  and
beneficial  owner of the number of Securities of Atlantic Coast  Polymers,  Inc.
shown on SCHEDULE 3.39,  which  Securities  owned by ADCS Nevada  represent less
than twenty  percent (20%) of the issued and  outstanding  voting  Securities of
Atlantic Coast  Polymers,  Inc. and which  Securities  owned by ADCS Nevada have
been fully paid and are nonassessable. Neither the ADCS Group nor any ADCS Group
Subsidiary is liable,  directly or indirectly,  whether as co-maker,  guarantor,
surety or otherwise, for any of the liabilities or obligations of Atlantic Coast
Polymers, Inc.

     3.40. No  Misrepresentation.  Neither this Agreement nor any certificate or
Schedule or other  information  furnished  pursuant to this  Agreement  by or on
behalf  of the ADCS  Group or any ADCS  Group  Subsidiary  contains  any  untrue
statement  of a material  fact or, when this  Agreement  and such  certificates,
Schedules and other  information are taken in their  entirety,  omits to state a
material  fact  required to be stated  herein or therein  necessary  to make the
statements contained herein or therein not misleading.


                                   ARTICLE IV

                Representations and Warranties of the ATMI Group

     The ATMI Group hereby  jointly and  severally  represent and warrant to the
ADCS Group that,  except as set forth in the ATMI DISCLOSURE  SCHEDULE  attached
hereto  (which  ATMI  Disclosure   Schedule  makes  explicit  reference  to  the
particular  subsection as to which exception is taken,  which in each case shall
constitute the sole subsection as to which such exception  shall apply,  and the
statements in such ATMI Disclosure Schedule shall






     be deemed to be representations and warranties),  as supplemented  pursuant
to Section 5.19, and acknowledge and confirm that the ADCS Group is relying upon
such  representations and warranties in connection with the execution,  delivery
and performance of this Agreement and the Additional Agreements to which it is a
party,  notwithstanding  any  investigation  made by the  ADCS  Group  or on its
behalf:

     4.1. Capitalization; Options, Warrants, Rights. SCHEDULE 4.1 sets forth the
aggregate  number of all of the  Securities  which the ATMI  Group and each ATMI
Group  Subsidiary  (as  hereinafter  defined) are authorized to issue (the "ATMI
Group  Securities") and the aggregate number of all of the ATMI Group Securities
issued and outstanding.  All ATMI Group Securities have been validly  authorized
and  issued and are fully paid and  nonassessable,  and have not been  issued in
violation of any preemptive,  first refusal or other subscription  rights of any
holder of any ATMI Group Securities or any other person, and have been issued in
compliance  with applicable  foreign,  federal and state  securities  laws. With
respect to the ATMI Group,  there are no  outstanding  or existing  (i) proxies,
voting trusts, or other agreements or understandings  with respect to the voting
of the ATMI Group Securities known to the ATMI Group, (ii) ATMI Group Securities
convertible into or exchangeable for other ATMI Group Securities, (iii) options,
warrants  or other  rights to purchase or  subscribe  for ATMI Group  Securities
(other  than  this  Agreement)  or ATMI  Group  Securities  convertible  into or
exchangeable  for other ATMI Group  Securities,  or (iv)  agreements of any kind
relating to the  issuance or purchase  of ATMI Group  Securities  or  Securities
convertible into or exchangeable for other ATMI Group  Securities.  No member of
the ATMI Group holds or owns,  directly or  indirectly,  any  Securities  of any
other corporation, or has any direct or indirect equity or ownership interest in
any  association,  partnership,  joint  venture or other  entity  other than (i)
through  mutual  funds  or  other  similar  investment  vehicles  over  which no
investment  discretion is retained,  (ii)  publicly-traded  Securities  having a
market value of $25,000 or less per issuer, (iii) ATMI Group Securities and (iv)
as identified on SCHEDULE 4.1 (each corporation, association, partnership, joint
venture or other entity in which any member of the ATMI Group owns,  directly or
indirectly,  twenty  percent  (20%)  or  more  of  the  issued  and  outstanding
Securities are referred to herein as the "ATMI Group Subsidiaries").

     4.2.  Organization;  Good Standing;  Power.  (a) Each of the ATMI Group and
each of the ATMI Group  Subsidiaries is a corporation  duly  organized,  validly
existing and in good standing under the laws of its state of  incorporation,  is
authorized  to do business as a foreign  corporation  in the  jurisdictions  set
forth on SCHEDULE 4.2 and is not required to be  authorized  to do business as a
foreign  corporation  in any other  jurisdiction  (within or without  the United
States) by reason of the nature of the business now being conducted by it or the
properties  owned or leased or  operated  by it in which  the  failure  to be so
qualified  would  have a material  adverse  effect on the  assets,  liabilities,
results of operations, financial condition or business of the ATMI Group and the
ATMI Group Subsidiaries taken as a whole (an "ATMI Material Adverse Effect").

     (b) Each of the ATMI Group has the requisite  corporate power and authority
to own,  lease and operate its  properties  and carry on its  business as is now
being  conducted by it, and to execute,  deliver and perform this  Agreement and
the Additional Agreements to which it is a party and consummate the transactions
contemplated hereby and thereby.

     (c) The ATMI Group and each ATMI Group  Subsidiary  conducts  its  business
under the trade names and other assumed names set forth on SCHEDULE 4.2, if any.

     4.3. Organizational Documents. With respect to the ATMI Group and each ATMI
Group Subsidiary, the ATMI Group has heretofore made available to the ADCS Group
a complete and correct copy of (i) each corporation's Certificate or Articles of
Incorporation,  as amended to date,  and (ii) each  corporation's  By- Laws,  as
amended  to date  (items  (i) and (ii)  being  referred  to  herein as the "ATMI
Organizational Documents").  Each of the foregoing are in full force and effect,
and none of the ATMI Group,  any ATMI Group  Subsidiary  or to the ATMI  Group's
knowledge, any other party to the ATMI Organizational Documents, is in violation
of any of the provisions thereof.  There are no proceedings for the amendment or
modification of or any other change in the ATMI Organizational Documents.  There
are no proceedings  for the  dissolution or liquidation of the ATMI Group or any
ATMI Group  Subsidiary or, to the knowledge of the ATMI Group,  threatening  the
existence of the ATMI






     Group or any ATMI Group  Subsidiary.  The ATMI Group has made  available to
the ADCS Group the  minute  books and stock  records of each  member of the ATMI
Group and ATMI Group Subsidiary.

     4.4. Authorization.  Except for the vote of ATMI stockholders  contemplated
hereby, the ATMI Group has taken all corporate action necessary to authorize the
execution,  delivery and  performance of this Agreement and, as applicable,  the
Additional  Agreements  to which it is a party.  Such  execution,  delivery  and
performance and the other transactions  contemplated  hereby do not and will not
violate,  result in any default,  acceleration  or loss of any material  benefit
under,  permit any third party to rescind any term or provision  of, or conflict
with any terms of, the ATMI  Organizational  Documents,  any law,  lien,  order,
award,  judgment,  decree,  Permit,  or any material  agreements or contracts to
which the ATMI Group or any ATMI Group Subsidiary is a party or is subject or by
which the ATMI Group or any ATMI Group  Subsidiary  or their  assets is bound or
result in the  creation  of any  lien,  charge  or  encumbrance  upon any of the
assets, real, personal or mixed,  tangible or intangible,  of the ATMI Group, or
any ATMI Group Subsidiary.  This Agreement and each of the Additional Agreements
to which any of the ATMI  Group is a party when  executed  will  constitute  the
legal, valid and binding obligation of the ATMI Group,  enforceable  against the
ATMI Group in  accordance  with its terms,  subject  to  applicable  bankruptcy,
insolvency,   fraudulent   transfer  and  other   similar  laws   affecting  the
enforceability of creditors' rights generally.

     4.5. SEC  Compliance.  Since  November 23, 1993,  ATMI has filed all forms,
reports and documents  (including all exhibits  required to be filed  therewith)
with the SEC (the "ATMI SEC  Documents")  required to be filed by it pursuant to
the federal securities laws and the SEC rules and regulations thereunder.  As of
their respective  filing dates, the ATMI SEC Documents  complied in all material
respects  with the  requirements  of the  Securities  Exchange  Act of 1934,  as
amended (the "Exchange Act"), or the Securities Act or the rules and regulations
promulgated  under  either,  and none of the ATMI SEC  Documents  contained  any
untrue statement of a material fact or omitted to state a material fact required
to be stated therein or necessary in order to make the statements  made therein,
in light of the circumstances under which they were made, not misleading, except
to the extent corrected by a subsequently filed ATMI SEC Document. ATMI has made
available to the ADCS Group copies of all of the ATMI SEC Documents.

  4.6. ATMI Commitments

     (a) Definitions.  The following definition shall apply for purposes of this
Section 4.6:

     (i) "ATMI Commitments" means all of the Commitments to which the ATMI Group
or any ATMI Group  Subsidiary  is a party  other  than the ATMI  Group  Employee
Benefit Plans (as hereinafter defined).

     (b) Schedule of ATMI  Commitments  and Proposals.  SCHEDULE 4.6 hereto sets
forth a list of the following:

     (i) any ATMI  Commitments,  not  including  purchase  orders  placed by any
member of the ATMI  Group,  creating  or  evidencing  indebtedness  in excess of
$100,000.00 for money borrowed by the ATMI Group or any ATMI Group Subsidiary;

     (ii) any material  ATMI  Commitments  mortgaging,  pledging,  granting,  or
creating  a lien or  security  interest  or  other  encumbrance  on any  real or
personal property of the ATMI Group or any ATMI Group Subsidiary;

     (iii) any ATMI Commitments  creating or evidencing any guaranty by the ATMI
Group or any ATMI Group  Subsidiary of payment or performance by any other party
involving in excess of $100,000.00;

     (iv) any ATMI  Commitments  involving  a sharing of  profits  or  expenses,
including, but not limited to, any joint venture agreements;

     (v) any ATMI Commitments limiting the freedom of the ATMI Group or any ATMI
Group Subsidiary to engage in any line of business;

     (vi) any ATMI  Commitments  limiting  the  freedom of the ATMI Group or any
ATMI Group Subsidiary to operate in any geographic area;





     (vii) any ATMI  Commitments  limiting  the freedom of the ATMI Group or any
ATMI Group Subsidiary to compete with any party;

     (viii) any ATMI  Commitments  limiting the freedom of the ATMI Group or any
ATMI  Group  Subsidiary  to  disclose  or use any  information  material  to the
operation of the business of the ATMI Group or any ATMI Group Subsidiary;

     (ix) any ATMI Commitments for construction of physical facilities involving
in excess of $100,000.00;

     (x) any ATMI Commitments providing for disposition of any line of business,
material assets or ATMI Group Securities;

     (xi)  any  ATMI  Commitments  providing  for  acquisition  of any  line  of
business,  material assets or Securities of any other business, which Securities
have a fair market value in excess of $50,000; and

     (xii) any ATMI Commitments providing for merger or consolidation (including
letters of intent) with any other business.

     (c) The ATMI  Group and each ATMI Group  Subsidiary  have  complied  in all
material  respects  with and are not in material  default  under any of the ATMI
Commitments.

  (d)Neither  the ATMI Group nor any ATMI Group  Subsidiary  has granted or been
     granted any waiver or forbearance with respect to any ATMI Commitments to
provide goods or services to customers that produced  aggregate  payments in the
year ending  December 31, 1996 of at least  $250,000.00 to the ATMI Group or any
ATMI Group Subsidiary.

     (e) The ATMI  Commitments  listed on Schedule 4.6 are valid and are in full
force and effect as to the ATMI Group or an ATMI Group  Subsidiary,  as the case
may be (and, to the knowledge of the ATMI Group, the other parties thereto).

     4.7.  Restrictions;  Burdensome  Agreements.  None of the ATMI Group or any
ATMI  Group  Subsidiary  is a party to any  contract,  commitment  or  agreement
(including the ATMI  Commitments),  and none of the ATMI Group or any ATMI Group
Subsidiary  or any of their  respective  properties  and assets is subject to or
bound  or  affected  by  any  charter,  by-law,  operating  agreement,   limited
partnership  agreement,  or  other  organizational  restriction,  or any  order,
judgment,  decree, law, statute,  ordinance,  rule, regulation,  Permit or other
restriction  of any kind or  character,  which  would (i) prevent the ATMI Group
from entering into this Agreement and the Additional Agreements to which it is a
party or prevent the ATMI Group from consummating the transactions  contemplated
hereby and thereby,  or (ii) have an ATMI Material  Adverse  Effect that has not
been disclosed in a Schedule hereto.

     4.8.  Condition  of the Assets.  Except as would not have an ATMI  Material
Adverse  Effect,  the  tangible  assets of the ATMI  Group  and each ATMI  Group
Subsidiary, including real, personal and mixed, material to the operation of its
business are in good condition and repair,  ordinary wear and tear excepted, and
suitable for the uses intended. The assets of the ATMI Group and each ATMI Group
Subsidiary  are  operated  in  conformity  in all  material  respects  with  all
applicable laws, ordinances, regulations, orders, Permits and other requirements
relating thereto adopted or currently in effect.  SCHEDULE 4.8 sets forth a list
of each asset (other than  intangible  assets  listed on SCHEDULE 4.23 and other
than as set forth on  SCHEDULE  4.25)  having a book value in excess of $50,000,
indicating  whether  each such asset is owned or leased by the ATMI Group or any
ATMI Group Subsidiary, and setting forth where each such asset is located. Since
December 31,  1996,  neither the ATMI Group nor any ATMI Group  Subsidiary  has,
except  in the  ordinary  course  of  business,  acquired  or sold or  otherwise
disposed of any of its assets.  SCHEDULE 4.8 also  includes a list of each lease
under which the ATMI Group or any ATMI Group  Subsidiary  leases an asset (other
than leased real  property)  having a replacement  cost of $50,000 or more.  The
leases and other  agreements  or  instruments  under which the ATMI Group or any
ATMI Group Subsidiary holds, leases,  subleases or is entitled to the use of any
of the assets having a replacement cost of $50,000 or more are in full force and
effect, and all rentals, royalties or other payments payable





     thereunder  have been duly paid or provided  for by adequate  reserves.  No
default  or event of  default  by the ATMI  Group or any ATMI  Group  Subsidiary
exists,  and no event  which,  with  notice  or  lapse  of time or  both,  would
constitute  a  default  by the  ATMI  Group or any ATMI  Group  Subsidiary,  has
occurred and is continuing,  under terms or provisions,  express or implied,  of
any such lease,  agreement or other  instrument or under the terms or provisions
of any agreement to which any of its assets is subject, which lease,  agreements
or other  instruments  individually or in the aggregate  involve assets having a
book  value of $50,000 or more,  nor has the ATMI Group  received  notice of any
claim of such default.

     4.9. Title; Absence of Liens and Encumbrances, Etc. The ATMI Group and each
ATMI Group Subsidiary have good, valid, and marketable title to its assets, free
and clear of all mortgages,  security interests,  claims, liens, charges,  title
defects, encumbrances, restrictions on use or transfer or other defects.

     4.10. Government and Other Consents. No consent,  authorization or approval
of,  exemption by, or filing with any  governmental,  public or  self-regulatory
body or authority or other party is required in connection  with the  execution,
delivery and  performance  by the ATMI Group of this  Agreement,  the Additional
Agreements  to  which  it is a party  or any of the  instruments  or  agreements
required  to be  executed  and  delivered  pursuant  to  this  Agreement  or any
Additional  Agreement,  or the  consummation  of the Exchange,  except under any
applicable  federal  and state  securities  laws,  the HSR Act and the rules and
regulations of the NASD.

     4.11. Franchises,  Permits,  Licenses;  Compliance with Applicable Laws and
Court Orders.  Except for intellectual property matters covered by Section 4.23,
the ATMI Group and each ATMI Group Subsidiary have all Permits necessary to own,
lease or operate its  properties or necessary for the conduct of its business as
currently  conducted,  other than those the absence of which would not result in
an ATMI Material Adverse Effect.  All such Permits are in full force and effect,
and there is no condition, nor has any event occurred, which constitutes or with
the giving of notice,  or passage of time, or both, would constitute a violation
of the  terms  of  any  Permit,  and to the  knowledge  of the  ATMI  Group,  no
suspension or cancellation of any of them is pending or threatened.  Neither the
execution of this  Agreement or the  Additional  Agreements  to which any of the
ATMI  Group is a party nor the  consummation  of the  transactions  contemplated
hereby or thereby  would  constitute a violation of the terms of any such Permit
or grounds for the  termination of any such Permit.  No application for a Permit
filed by or on  behalf of the ATMI  Group or any ATMI  Group  Subsidiary,  or in
connection  with a  facility  operated  by the  ATMI  Group  or any  ATMI  Group
Subsidiary,  within  the last  five (5) years has been  denied,  other  than the
denial of Permits  which  individually  or in the  aggregate did not or does not
have an ATMI  Material  Adverse  Effect.  The ATMI  Group  and each  ATMI  Group
Subsidiary  have,  in the  operation of its  business,  duly  complied  with all
applicable laws, rules, regulations, Permits and orders of federal, state, local
and foreign governments,  except where the failure to comply did not or does not
have an ATMI Material Adverse Effect.  Neither the ATMI Group nor any ATMI Group
Subsidiary  is in  default,  and no event has  occurred  that with notice or the
passage of time or both would  constitute  such a default,  with  respect to any
order, judgment, writ, injunction,  decree, award, Permit, rule or regulation of
any court,  governmental  or regulatory  body or arbitrator  which  restrains or
limits in any material  respect the  operation of the business of, or the use of
the assets of, the ATMI Group and the ATMI Group  Subsidiaries taken as a whole.
To the knowledge of the ATMI Group, no officer,  director,  member or partner of
the ATMI  Group  would be  unable  to give the  representation  that none of the
events  or  circumstances  described  in Rule  262 of  Regulation  A  under  the
Securities Act have occurred.

  4.12. Financial Statements. The (i) audited consolidated balance sheets of
     ATMI and its  subsidiaries at December 31, 1994 and 1995 and the statements
of
operations  and  changes  in  stockholders'  equity and cash flows for the years
ended  December 31, 1994 and 1995, and (ii) the unaudited  consolidated  balance
sheet at September 30, 1996 and the  statement of operations  and cash flows for
the  nine  months  then  ended  and  the  unaudited  consolidated  statement  of
operations for the three months ended  September 30, 1996,  included in the ATMI
SEC Documents  (the "ATMI  Financial  Statements")  fairly present the financial
position  and results of  operations  of the ATMI Group as for the periods  then
ended and the  financial  position  of the ATMI  Group at the dates  thereof  in
accordance  with generally  accepted  accounting  principles  (subject to normal
year-end adjustments for unaudited interim financial  statements,  if any). ATMI
has maintained its books of account in accordance  with applicable  laws,  rules
and regulations of government authorities and with generally accepted





accounting  principles  consistently applied, and such books of account are and,
during the period covered by the ATMI  Financial  Statements  were,  correct and
complete in all material  respects,  fairly and accurately  reflect or reflected
the income,  expenses,  assets and  liabilities  of ATMI,  including  the nature
thereof and the transactions giving rise thereto, and provide or provided a
     fair  and  accurate  basis  for  the  preparation  of  the  ATMI  Financial
Statements.

     4.13.  Absence of Undisclosed  Liabilities.  Neither the ATMI Group nor any
ATMI Group  Subsidiary has any  liabilities  or  obligations,  either  absolute,
accrued,  contingent or otherwise,  which individually or in the aggregate would
have an ATMI Material  Adverse  Effect and which (i) have not been  reflected in
the ATMI Financial Statements, (ii) have not been described in this Agreement or
in any of the Schedules  hereto,  or (iii) have been incurred since December 31,
1996,  other than in the ordinary  course of its business  consistent  with past
practices.

     4.14.  Absence of Certain  Changes.  Since  December 31, 1996 there has not
been, except as described in SCHEDULE 4.14 hereto:

     (a) any  material  adverse  change in the  business,  financial  condition,
assets or liabilities, results of operations, or prospects of the ATMI Group and
the ATMI Group  Subsidiaries taken as a whole other than changes in the ordinary
course of business, which changes have not in the aggregate been, and do not, to
the ATMI  Group's  knowledge,  threaten  to  become,  materially  adverse to the
business, financial condition, assets or liabilities,  results of operations, or
prospects of the ATMI Group and the ATMI Group Subsidiaries taken as a whole;

     (b) any damage,  destruction  or loss in excess of $25,000  (whether or not
covered by insurance)  adversely  affecting any of the assets or business of the
ATMI Group or any ATMI Group Subsidiary;

     (c) any ATMI  Commitment  or liability  undertaken  or incurred by the ATMI
Group or any ATMI Group Subsidiary  (whether  absolute,  accrued,  contingent or
otherwise and whether due or to become due), or any transaction  entered into by
the ATMI Group or any ATMI Group  Subsidiary which is material to the ATMI Group
and the ATMI Group  Subsidiaries  taken as a whole, other than items incurred or
entered  into in the  ordinary  course  of  business  and  consistent  with past
practices of the ATMI Group or any ATMI Group Subsidiary;

     (d) any payment,  discharge or satisfaction of any claim, lien, encumbrance
or liability of the ATMI Group or any ATMI Group Subsidiary outside the ordinary
course of business in excess of $5,000 individually or $50,000 in the aggregate;

     (e) any sale, transfer,  conveyance,  assignment,  lease, license,  pledge,
mortgage or other disposition or encumbrance by the ATMI Group or any ATMI Group
Subsidiary of any asset of the ATMI Group or any ATMI Group Subsidiary  having a
value more than $20,000 individually or $50,000 in the aggregate,  except in the
ordinary course of business and consistent with past practices of the ATMI Group
or any ATMI Group Subsidiary;

     (f) any modification,  amendment,  cancellation,  termination,  revocation,
rescission,  or waiver of any  rights  with  value to the ATMI Group or any ATMI
Group Subsidiary in excess of $20,000 pursuant to any ATMI Commitments;

     (g) any material change in the accounting  methods or practices followed by
the ATMI Group or any ATMI Group Subsidiary or any change in the depreciation or
amortization policies or rates theretofore adopted and applied;

     (h) any (i) grant of any  severance  or  termination  pay to any  director,
officer,  employee,  partner  or  member  of the ATMI  Group  or any ATMI  Group
Subsidiary  in  excess  of  $25,000,  (ii)  entering  into  of  any  employment,
severance,  management,  consulting,  deferred  compensation  or  other  similar
agreement (or any amendment to any





     such existing agreement) with any director,  officer,  employee, partner or
member of the ATMI Group or any ATMI  Group  Subsidiary,  except for  employment
agreements  entered into in the ordinary  course of business  (which  agreements
individually or in the aggregate are not material to the financial  condition or
results of operations of the ATMI Group and the ATMI Group Subsidiaries taken as
a  whole),  (iii)  change  in  benefits  payable  under  existing  severance  or
termination  pay policies or employment,  severance,  management,  consulting or
other similar agreements,  other than normal yearly adjustments,  or (iv) change
in  compensation,  bonus or other  benefits  payable to any  director,  officer,
employee,  partner  or member of the ATMI  Group or any ATMI  Group  Subsidiary,
other than normal yearly  adjustments,  and other than any increase  pursuant to
any ATMI Group Employee  Benefit Plan, the formulae or commission rates of which
have not been amended or changed;

     (i)  declared,  paid or set aside for payment by the ATMI Group or any ATMI
Group  Subsidiary  any dividend or other  distribution  in respect of ATMI Group
Securities, or redeemed, purchased or otherwise acquired any of their respective
ATMI Group Securities;

     (j) issued,  authorized  for  issuance,  or entered into any  commitment to
issue any Security, bond, note or other debt obligation of the ATMI Group or any
ATMI Group Subsidiary;

     (k) any transaction or payments  between (i) any stockholder or any related
party or entity and (ii) the ATMI Group or any ATMI Group  Subsidiary not in the
ordinary course of business, other than indebtedness which by its terms does not
require payment of principal or interest at any time after December 31, 1997;

     (l) the  termination,  whether  voluntary or  involuntary,  of any material
employee  of the ATMI  Group or any ATMI  Group  Subsidiary  or of any  material
relationship  between  the  ATMI  Group  or  any  ATMI  Group  Subsidiary  and a
consultant; or

     (m) any  agreement or  understanding  entered into by the ATMI Group or any
ATMI Group Subsidiary whether in writing or otherwise, for the ATMI Group or any
ATMI Group Subsidiary to take any of the actions specified in this Section 4.14.

     4.15.  Indebtedness.  Neither the ATMI Group nor any ATMI Group  Subsidiary
has any  obligation  for money borrowed or under any guarantee nor any agreement
or  arrangement to borrow money or to enter into any such  guarantee,  and as of
the Closing Date, neither the ATMI Group nor any ATMI Group Subsidiary will have
any  obligation  for money  borrowed nor any agreement or  arrangement to borrow
money,  and neither the ATMI Group nor any ATMI Group  Subsidiary  will have any
guarantee  outstanding  nor any  agreement or  commitment to enter into any such
guarantee,  which with respect to any of the above is material to the ATMI Group
and the ATMI Group Subsidiaries taken as a whole.

     4.16. Accounts Receivable.  No amounts in excess of $10,000 individually or
$50,000 in the aggregate  included in the accounts  receivable of the ATMI Group
or any ATMI Group Subsidiary in the ATMI Financial Statements have been released
or are, or are  currently  expected to be,  regarded  under  generally  accepted
accounting  principles as unrecoverable in whole or in part except to the extent
there shall have been an appropriate bad debt reserve therefor. Such receivables
are not,  to the  knowledge  of the ATMI  Group,  subject  to any  counterclaim,
refusal to pay or setoff not  reflected  in the  reserves  set forth on the ATMI
Financial  Statements.  SCHEDULE  4.16 hereto sets forth a list of all  accounts
receivable  of the ATMI  Group or any ATMI Group  Subsidiary  as of the close of
business on December 31, 1996, none of which, to the ATMI Group's knowledge,  is
owing from a debtor that has become bankrupt or insolvent or has been pledged to
any third party.

     4.17.  Supplies.  The  supplies  of the  ATMI  Group  and  the  ATMI  Group
Subsidiaries  taken as a whole  consist  of a  quality  and  quantity  generally
adequate for and usable in the ordinary course of business  consistent with past
practice.

     4.18. No Prebillings.  Neither the ATMI Group nor any ATMI Group Subsidiary
has prebilled or received  payment in amounts greater than $20,000  individually
or $50,000 in the aggregate, and the ATMI Group and the





     ATMI  Group  Subsidiaries  will not  prebill  or  receive  payment  in such
amounts,  from any of its  accounts for goods to be delivered or for services to
be rendered  or for  expenses to be  incurred  subsequent  to the Closing  Date,
except in  connection  with any  government  contract and except in the ordinary
course of business and  consistent  with past practices of the ATMI Group or any
ATMI Group Subsidiary.

  4.19. Taxes.

     (a) All Returns  related to Taxes  required to be filed or maintained on or
before the Closing Date with respect to the  business,  activities  or assets of
the ATMI Group or any ATMI Group Subsidiary,  have been filed or maintained,  or
will be filed or maintained  on or before the Closing  Date, in accordance  with
all applicable laws (after taking into account extensions duly obtained), and no
penalties or other charges are due or could reasonably be expected to become due
with  respect  to the late  filing of any  Return.  All  Returns  are or will be
accurate and complete in all  material  respects and properly  reflect the Taxes
due for the periods covered thereby.  All Taxes due and payable,  whether or not
called for by the Returns, and all Taxes properly allocable to periods ending on
or before the Closing Date have been paid,  adequately  provided for in the ATMI
Financial  Statements or any ATMI Group Subsidiary's  financial  statements,  or
properly protested or will be so paid,  reserved for or protested by the Closing
Date,  and the ATMI Group and each ATMI Group  Subsidiary  have  maintained  all
required  records  with respect to Taxes.  All Taxes  required to be withheld or
collected by the ATMI Group or any ATMI Group Subsidiary have been duly withheld
or  collected  and  have  been  paid  over  to  the   appropriate   governmental
authorities,  or are held in separate bank accounts established  exclusively for
such  purpose.  Except  as set  forth  on  SCHEDULE  4.19  hereto,  no  audit or
investigation  of any Return is pending or, to the  knowledge of the ATMI Group,
threatened.  SCHEDULE  4.19  hereto  sets  forth the status of any audit that is
pending,  including  the  amounts  of  any  deficiencies  and  additions  to Tax
indicated  on any  notices  of  proposed  deficiency  or  statutory  notices  of
deficiency  that may have been issued in  connection  therewith  and all of such
deficiencies  or  additions  to Tax have been paid.  There are no  requests  for
rulings pending before any taxing authority. SCHEDULE 4.19 sets forth the states
in which the ATMI Group or any ATMI Group  Subsidiary has filed Returns relating
to Taxes for the taxable  years ended  December  31, 1993  through  December 31,
1995. Neither the ATMI Group nor any ATMI Group Subsidiary has executed or filed
with the  Internal  Revenue  Service or any other  domestic  or  foreign  taxing
authority any agreement extending the period for assessment or collection of any
Taxes,  and neither the ATMI Group nor any ATMI Group  Subsidiary has waived any
law or  regulation  fixing the period for  assessment  or  collection  of Taxes.
Neither the ATMI Group nor any ATMI Group  Subsidiary  is a party to any pending
action or  proceeding  by any  domestic or foreign  governmental  authority  for
assessment or collection of Taxes,  and no claim for assessment or collection of
Taxes has been asserted or  threatened  against the ATMI Group or any ATMI Group
Subsidiary  for  which  provision  has  not  been  made  in the  ATMI  Financial
Statements or any ATMI Group Subsidiary's financial statements. There are no tax
liens upon any of the  properties  or assets of the ATMI Group or any ATMI Group
Subsidiary other than liens for Taxes not yet due and payable. True and complete
copies  of the  income  tax  returns  of the  ATMI  Group  and each  ATMI  Group
Subsidiary  for the three (3) fiscal years ended in 1993 through  1995, as filed
with the  Internal  Revenue  Service and all other  domestic  or foreign  taxing
authorities, have previously been made available to the ATMI Group.

     (b) No sales,  use or other transfer or conveyance taxes are or will become
payable  by the ADCS  Group or the ATMI  Group  solely as a  consequence  of the
Merger,  Exchange or Reorganization,  other than taxes based upon the net income
of the parties.

     4.20. Employees.  SCHEDULE 4.20 contains a true and complete list of all of
the  officers  and  directors,  partners  and members of the ATMI Group and ATMI
Group  Subsidiaries,  specifying  their office or title, and a true and complete
list of all the employees of the ATMI Group and each ATMI Group Subsidiary as of
the date hereof.  Neither the ATMI Group nor any ATMI Group  Subsidiary  has any
written or oral  contract of  employment  with any employee of the ATMI Group or
any ATMI  Group  Subsidiary,  and  neither  the ATMI  Group  nor any ATMI  Group
Subsidiary is a party to or subject to any collective  bargaining  agreement nor
has  been a party  to or  subject  to any  collective  bargaining  agreement  or
collective  bargaining  plan  during the last five (5) years.  Neither  the ATMI
Group nor any ATMI Group  Subsidiary  is a party to any pending nor, to the ATMI
Group's knowledge, threatened labor dispute affecting the ATMI Group or any ATMI
Group Subsidiary.





     The ATMI Group and each ATMI Group Subsidiary have complied in all material
respects with all applicable foreign, federal, state and local laws, ordinances,
rules and  regulations  and  requirements  relating to the  employment of labor,
including,  but not limited to, the provisions thereof relative to wages, hours,
collective bargaining,  drug testing, personnel policies and practices,  payment
of Social Security, unemployment and withholding taxes, and ensuring equality of
opportunity  for  employment and  advancement  of minorities  and women.  To the
knowledge  of the  ATMI  Group,  neither  the  ATMI  Group  nor any  ATMI  Group
Subsidiary  is liable  for any  arrears of wages or any taxes or  penalties  for
failure to comply with any of the foregoing.  None of the ATMI Group or any ATMI
Group  Subsidiary has received  notice from any employee listed on SCHEDULE 4.20
as earning an annual  base  salary in excess of $40,000  that such  employee  is
terminating  his or her  employment  with  the  ATMI  Group  or any  ATMI  Group
Subsidiary, nor to the knowledge of the ATMI Group does any such employee intend
to  terminate  his or her  employment  with  the ATMI  Group  or any ATMI  Group
Subsidiary.

  4.21. Employee Benefit Plans.

     (a) SCHEDULE 4.21 sets forth a list of every stock option,  stock purchase,
stock appreciation right, bonus,  incentive,  deferred or current  compensation,
excess  benefits,   profit  sharing,   pension,  thrift,  savings,   retirement,
severance, sickness, accident, medical, disability,  hospitalization,  vacation,
insurance or other plan or  agreement  which  provides  benefits to or for or on
behalf  of any one or  more  employees  of the  ATMI  Group  or any  ATMI  Group
Subsidiary  (including former employees) or their  beneficiaries  (collectively,
"ATMI Employee  Benefit  Plans").  The ATMI Group has made available to the ADCS
Group true,  correct and complete copies of all ATMI Employee  Benefit Plans, as
in effect on the date of this Agreement,  all written  descriptions or summaries
thereof, all trust agreements or other funding arrangements (including insurance
or group annuity  contracts)  relating thereto,  all amendments  thereto and all
determination  letters  issued by the Internal  Revenue  Service with respect to
such ATMI Employee Benefit Plans.

     (b) No employee  benefit plan (within the meaning of Section 3(3) of ERISA)
exists which covers or is maintained  for the benefit of any of the employees of
the ATMI  Group or any ATMI Group  Subsidiary  or to which the ATMI Group or any
ATMI  Group  Subsidiary  is  required  to make  contributions  on account of any
employees of the ATMI Group or any ATMI Group Subsidiary.

     (c) There are no  actions,  suits or claims  pending  (other  than  routine
claims for benefits) or, to the knowledge of the ATMI Group,  threatened against
any ATMI Employee  Benefit Plan,  nor, to the knowledge of the ATMI Group,  does
any basis therefor  exist.  Each ATMI Employee  Benefit Plan is in compliance in
all material respects with all applicable requirements of ERISA and the Code and
their  regulations,  and  other  applicable  laws and  regulations  and has been
administered  in all  material  respects in  accordance  with its terms and with
applicable legal requirements.

  (d) With respect to each ATMI Employee Benefit Plan,

     (i) the ATMI Group and each ATMI Group  Subsidiary have performed or caused
to be  performed  all  obligations  required  to be  performed  under  such ATMI
Employee Benefit Plan (including, but not limited to, the making when due of all
contributions  required by the terms of such plan, by law, or by any  collective
bargaining agreement, or otherwise);

     (ii) the ATMI Group and each ATMI Group  Subsidiary have complied in timely
fashion  with  the  terms  of each  ATMI  Employee  Benefit  Plan  and  with all
requirements of all laws, rules and regulations (including,  but not limited to,
ERISA and the Code) which are applicable to each ATMI Employee  Benefit Plan and
each ERISA Plan, including, but not limited to,

     (1)  the  filing  when  due of all  required  returns,  reports  and  other
documents, and

     (2) compliance with all rules concerning  notifications  and disclosures to
participants and beneficiaries under each such plan;






     (iii) neither the ATMI Group nor any ATMI Group  Subsidiary  has engaged in
any "prohibited  transaction"  within the meaning of Section 4975 of the Code or
Section 406 of ERISA nor has  committed  any breach of fiduciary  responsibility
under ERISA (or has any knowledge  that any other person has engaged in any such
prohibited  transaction  or committed  any such breach)  which could subject the
ADCS Group and/or the Surviving  Corporation to an excise tax or other liability
under ERISA or the Code; and

     (iv)  neither  the ATMI Group nor any ATMI Group  Subsidiary  is in default
under or in  violation  of (and has no  knowledge of any default or violation by
any other person of) the terms of any ATMI Employee Benefit Plan.

  (e) Except as set forth on SCHEDULE 4.21,

     (i) no employee  pension  benefit  plan (as  defined in Section  3(2)(A) of
ERISA) which is sponsored by any member of the "controlled group" (as defined in
Section  4001(a)(14)  of ERISA) which  includes the ATMI Group or any ATMI Group
Subsidiary (the "ATMI Controlled  Group") has been terminated since September 2,
1974;

     (ii) no  proceeding  has been  initiated  to  terminate  any such  employee
pension benefit plan;

     (iii) there has been no  "reportable  event" (within the meaning of Section
4043(c) of ERISA) with respect to any such employee  pension benefit plan, other
than those with respect to which the  requirement  of thirty (30) days'  notice,
whether  in advance of the event or  following  the event,  to the PBGC has been
waived by regulation;

     (iv) no excise or other  taxes  (or  interest  or  penalties  with  respect
thereto) are due or owing with respect to any such employee pension benefit plan
because of any failure to comply with the minimum funding  standards of ERISA or
for failing to comply with any other applicable  requirement  under ERISA or the
Code;

     (v) all  contributions  to any such employee pension benefit plan have been
made within the time provided by law;

     (vi) at no time  during  the last five (5) years has the ATMI  Group or any
ATMI Group  Subsidiary or any member of the ATMI  Controlled  Group been a party
to, or been required to make any  contribution  to, a  "Multiemployer  Plan" (as
defined  in Section  3(37) of  ERISA),  nor has the ATMI Group or any ATMI Group
Subsidiary or any member of the ATMI Controlled Group made a complete or partial
withdrawal  from a  Multiemployer  Plan as a  result  of  which  any  withdrawal
liability has been or will be incurred by any of them;

     (vii) neither the ATMI Group or any ATMI Group Subsidiary nor any member of
the ATMI Controlled  Group has incurred any liability to the PBGC other than for
the payment of annual  premiums (and no such premium  payments are currently due
and owing); and

     (viii)  neither the ATMI Group or any ATMI Group  Subsidiary nor any member
of the ATMI Controlled  Group has entered into any  transaction  within the past
five (5) years the  purpose  of which is to evade  liability  under  Title IV of
ERISA.

     (f) No ATMI  Employee  Benefit  Plan  (other  than one which is an employee
pension  benefit plan within the meaning of Section  3(2)(A) of ERISA)  provides
benefits  (including,  without  limitation,  death,  health or medical benefits,
whether or not insured) with respect to current or former  employees of the ATMI
Group or any ATMI Group Subsidiary  beyond their retirement or other termination
of  service  with the ATMI Group or any ATMI  Group  Subsidiary,  other than (i)
coverage mandated by applicable law, (ii) deferred  compensation  benefits which
have been  accrued  as  liabilities  on the books of the ATMI  Group or any ATMI
Group Subsidiary,  (iii) benefits the full cost of which is borne by the current
or former employees (or their  beneficiaries),  (iv) benefits which have already
been  satisfied  in full or (v) death  benefits  under any  pension  plan to the
extent set forth in SCHEDULE 4.21 hereto.





     4.22.  Litigation.  There is no action,  suit or proceeding  pending and of
which it has been served notice or, to the ATMI Group's  knowledge,  threatened,
by or  against  the ATMI  Group  or any ATMI  Group  Subsidiary  relating  to or
affecting its business or assets,  at law, in equity,  by way of  arbitration or
before any governmental  department,  commission,  board or agency.  To the ATMI
Group's  knowledge,  there are no existing facts or conditions  which reasonably
would be expected to give rise to any charge, claim, litigation,  proceeding, or
investigation  by  any  third  party  which  could  reasonably  be  expected  to
materially  adversely  affect  its  business,  the ATMI  Group or any ATMI Group
Subsidiary,  nor are there any facts or  conditions  which could  reasonably  be
expected  to give  rise to any  order of  condemnation,  appropriation  or other
taking of any of the assets. There is no litigation, action, suit, investigation
or  proceeding  pending  and of which  it has  been  served  notice  or,  to the
knowledge  of the ATMI  Group,  threatened,  before any  court,  agency or other
governmental  body against the ATMI Group or any ATMI Group  Subsidiary  (or any
corporation  or  entity  affiliated  with  the  ADCS  Group  or any  ATMI  Group
Subsidiary)  which  seeks to enjoin  or  prohibit  or  otherwise  challenge  the
transactions  contemplated hereby or contemplated by the Additional  Agreements.
Schedule 4.22 sets forth each action,  suit or proceeding against the ATMI Group
or any ATMI Group Subsidiary relating to or affecting its business or assets, at
law, in equity,  by way of  arbitration or before any  governmental  department,
commission,  board or agency,  which has been dismissed or settled or in which a
judgment has been rendered, in each case within the past five (5) years, and the
disposition  thereof. The ATMI Group has made available to ATMI true and correct
copies of each settlement  agreement and release, if any, in connection with any
matter discussed in the prior sentence, each of which constitutes a legal, valid
and  binding  obligation  of the  parties  thereto,  and no party  thereto is in
default  of any of its  obligations  thereunder.  There is no  order,  judgment,
decree or settlement  agreement  against or involving the ATMI Group or any ATMI
Group Subsidiary involving any ongoing liabilities or restrictions.

     4.23.  Proprietary Rights. (a) SCHEDULE 4.23 sets forth a true, correct and
complete list of all foreign and domestic  patents and applications for patents,
Marks, and registered copyrights,  and applications therefor,  owned by the ATMI
Group or any ATMI Group  Subsidiary or in which the ATMI Group or any ATMI Group
Subsidiary has any rights or licenses.  The ATMI Group has made available to the
ADCS  Group  copies  of all  agreements  of the ATMI  Group  or any  ATMI  Group
Subsidiary  with each  officer,  employee or consultant of the ATMI Group or any
ATMI Group Subsidiary providing the ATMI Group or any ATMI Group Subsidiary with
secrets  and  inventions  developed  or used by the ATMI Group or any ATMI Group
Subsidiary.  All of such  agreements  so described  are valid,  enforceable  and
legally binding.

     (b) The ATMI  Group and each ATMI Group  Subsidiary  own or possess or have
the right to obtain licenses or other rights to use all Proprietary Rights which
it has  determined  are  used in its  business,  and it  believes  the  same are
sufficient  to conduct its  business as it has been and is now being  conducted.
The ATMI Group is not aware of any  existing  Proprietary  Rights  that the ATMI
Group and the ATMI Group  Subsidiaries  do not already own or possess or will be
able to obtain a license under,  which Proprietary Rights would be necessary for
the ATMI Group or any ATMI Group Subsidiary to conduct its business.

     (c) To the ATMI Group's  knowledge,  the  operations  of the ATMI Group and
each ATMI Group Subsidiary do not conflict with or infringe upon, and no one has
asserted  to the ATMI Group or any ATMI Group  Subsidiary  that such  operations
conflict  with or  infringe  upon,  any  Proprietary  Rights  any  Marks  owned,
possessed or used by any third party.  There are no claims,  disputes,  actions,
proceedings,  suits or appeals  pending against the ATMI Group or any ATMI Group
Subsidiary  with respect to any Proprietary  Rights or Marks,  and none has been
threatened against the ATMI Group or any ATMI Group Subsidiary. To the ATMI

     Group's  knowledge,  there  are no  facts  or  alleged  facts  which  would
reasonably  serve as a basis for any claim that the ATMI Group or any ATMI Group
Subsidiary  does not have the  right to use,  free of any  rights  or  claims of
others, all Proprietary Rights and Marks in the development,  manufacture,  use,
sale or other  disposition  of any or all products or services  presently  being
used, furnished or sold in the conduct of its business as it has been and is now
being  conducted.  Neither  the ATMI  Group nor any ATMI  Group  Subsidiary  has
violated the terms of any confidentiality  agreement or nondisclosure  agreement
entered into in favor of any third party.





     (d) There are no inter parties  proceedings  before any patent or trademark
authority to which the ATMI Group or any ATMI Group Subsidiary is a party.

     (e) The ATMI  Group and each ATMI  Group  Subsidiary  have  taken all other
measures it deems  reasonable to maintain the  confidentiality  of the processes
and formulae,  research and development results and other know-how, the value of
which  to the ATMI  Group  or any  ATMI  Group  Subsidiary  is  contingent  upon
maintenance of the confidentiality thereof.

     (f)  Each  employee  and  officer  of the  ATMI  Group  or any  ATMI  Group
Subsidiary is a party to a confidential  non-disclosure  agreement with the ATMI
Group or such ATMI Group  Subsidiary  (the form of which has been made available
to the ADCS Group).  No employee of the ATMI Group or any ATMI Group  Subsidiary
is in violation of any material  term of any  employment  contract,  proprietary
information and inventions agreement, confidentiality agreement, non-competition
agreement,  or any other contract or agreement  relating to the  relationship of
any such  employee  with the ATMI  Group or any ATMI  Group  Subsidiary,  or any
previous employer.

     (g) The Proprietary  Rights and Marks are free of any unresolved  ownership
disputes with respect to any third party. To the ATMI Group's knowledge there is
no unauthorized use, infringement or misappropriation of any of such Proprietary
Rights or Marks by any third party, including any employee or former employee of
the ATMI Group or any ATMI Group Subsidiary.

     (h) Other than as part of  transactions  identified in SCHEDULE  4.23,  the
ATMI Group has not licensed, granted rights under, waived, released, discharged,
dedicated,  disclaimed or otherwise  relinquished any of the Proprietary  Rights
identified on SCHEDULE  4.23(H) (the "ATMI  Identified  Proprietary  Rights") to
third parties; has not burdened the Proprietary Rights with any liens,  security
interests,  financing agreements, or other encumbrances; and to the ATMI Group's
knowledge is not prevented in any manner,  as by estoppel,  laches,  inequitable
conduct,  or otherwise,  from enforcing any of the ATMI  Identified  Proprietary
Rights,  which  prevention  would  individually or in the aggregate have an ATMI
Material Adverse Effect.

     4.24. Related Party Transactions.  SCHEDULE 4.24 sets forth the amounts and
other essential terms of  indebtedness  (which by its terms requires  payment of
principal or interest at any time after December 31, 1997) or other obligations,
liabilities  or  commitments  (contingent or otherwise) of the ATMI Group or any
ATMI Group Subsidiary to or from any present officer, director,  partner, member
or  stockholder or any person  related to,  controlling,  controlled by or under
common  control with any of the foregoing  (other than for  employment  services
performed  within the past month the payment for which is not yet due),  and all
other  transactions  between  such  persons and the ATMI Group or any ATMI Group
Subsidiary,  except for transactions which through  consolidation are eliminated
in the ATMI Group Financial  Statements.  Without limiting the generality of the
foregoing,  as of the date  hereof,  none of the  present  officers,  directors,
partners,  members  or  stockholders  or any  person  related  to,  controlling,
controlled  by or under  common  control with any of the  foregoing  (a) has any
material direct or indirect  interest in any entity which does business with the
ATMI Group or any ATMI Group Subsidiary, (b) has any direct or indirect interest
in any  property,  asset  or right  which is used by the ATMI  Group or any ATMI
Group  Subsidiary  in the conduct of its  business,  or (c) has any  contractual
relationship  with the ATMI Group or any ATMI Group  Subsidiary  other than such
relationships which occur from being an employee, officer, director, etc.

  4.25. Environmental Matters; Health and Safety.

     (a) Definitions.  The definitions set forth in Section 3.31 shall apply for
purposes of this Section 4.25.

     (b) Environmental Representations and Warranties. SCHEDULE 4.25 hereto sets
forth a list of all of the real  property and all of the  buildings,  warehouses
and storage  facilities owned,  leased or operated by the ATMI Group or any ATMI
Group  Subsidiary  during  the  last  five  (5)  years  (the  "ATMI  Premises"),
indicating where such





     property or facility is located,  whether  such  property is owned,  leased
and/or  operated by the ATMI Group or any ATMI Group  Subsidiary and the date of
acquisition or occupancy thereof.

     (i) Compliance.  The ATMI Group and each ATMI Group  Subsidiary and, to the
ATMI Group's  knowledge,  its  predecessor(s) in interest,  have been and are in
compliance  with  and  have  no  liability  or  obligation   arising  under  any
Environmental  Law, and neither the ATMI Group nor any ATMI Group Subsidiary has
received  any  Notice  from  any  applicable  governmental  agency  seeking  any
information  or alleging  any  violation  of such  Environmental  Laws.  No Site
Remediation Measure is necessary or required under Environmental Law or any ATMI
Commitment  for  its  business  or  the  ATMI   Premises,   nor  are  there  any
Environmental   Conditions  on  the  ATMI  Premises.  No  capital  improvements,
alterations  or repairs to the ATMI  Premises are necessary or required to bring
such  facility  into  compliance  with all  Environmental  Laws now in effect or
enacted or promulgated but not yet in effect.

     (ii) Hazardous  Materials/Underground  Tanks. None of the ATMI Group or any
ATMI Group Subsidiary and, to the ATMI Group's knowledge,  their  predecessor(s)
in interest, has caused or permitted any use of its business or ATMI Premises to
generate,  manufacture,   refine,  transport,  treat,  store,  handle,  dispose,
transfer,  produce or process any Hazardous  Materials or solid waste, except in
compliance with all Environmental  Laws, and has not caused or permitted and has
no knowledge of the Release of any such Hazardous  Materials on-site or off-site
of the  ATMI  Premises  resulting  or that  could  in the  future  result  in an
Environmental  Condition requiring Site Remediation Measures.  The ATMI Premises
and all principal  items and  machinery  and equipment  used in the ATMI Group's
business comply with all applicable Environmental Laws. The ATMI Premises do not
contain any asbestos  requiring  removal now or in the course of any  remodeling
that may occur in the future,  or other  Hazardous  Materials,  and,  except for
chemicals and raw materials used, and wastes  generated in connection  with, the
manufacture of the ATMI Group's products,  which in each case are located on the
ATMI Premises in the ordinary course of business,  no such materials are located
on, in or under the ATMI Premises. Any and all underground and aboveground tanks
at the ATMI Premises are in compliance with any and all Environmental  Laws, and
such Environmental Laws do not mandate the removal or retrofitting of such tanks
for a period of five (5) years  after the  Closing.  The removal of any tank has
been carried out in compliance with all applicable Environmental Laws.

     (iii)  There  are  no  outstanding  or,  to  the  ATMI  Group's  knowledge,
threatened  actions,  claims,  proceedings,  determinations  or judgments by any
party, including but not limited to any governmental authority, whether foreign,
federal, state, local or any agency thereof, against or involving the ATMI Group
or any ATMI  Group  Subsidiary,  or to the ATMI  Group's  knowledge,  against or
involving  the ATMI  Group's or any ATMI Group  Subsidiary's  predecessor(s)  in
interest  in any manner  arising  under the  Environmental  Laws or  alleging or
involving  personal  injury or property damage as a result of a violation of any
Environmental  Law or otherwise  involving  Environmental  Conditions.  Attached
hereto as  SCHEDULE  4.25 is a list of all such  actions,  claims,  proceedings,
determinations  and judgments issued within the past ten (10) years by any party
against the ATMI Group or any ATMI Group  Subsidiary  and,  to the ATMI  Group's
knowledge, against any predecessor(s) in interest.

     (iv) The ATMI Group and each ATMI Group Subsidiary and, to the ATMI Group's
knowledge,  their  predecessor(s)  in interest,  have  complied with all notice,
recordkeeping and reporting  requirements imposed by any governmental  authority
and any informational  requests or demands arising under any Environmental Laws.
None of the ATMI Group or any ATMI Group  Subsidiary,  nor, to the ATMI  Group's
knowledge,  the ATMI Group's or any ATMI Group  Subsidiary's  predecessor(s)  in
interest,  is liable for any penalties,  fines,  or forfeitures or is subject to
any  restrictions  on the conduct of its business for failure to comply with any
of the foregoing.

     4.26.  Customers and  Suppliers.  Neither the ATMI Group nor any ATMI Group
Subsidiary  has received any notice or has any knowledge  that any customer from
whom the ATMI Group or any ATMI Group  Subsidiary  in the aggregate has received
more  than  $250,000  in  gross  receipts  during  the   immediately   preceding
twelve-month  period (1) has ceased,  or currently  intends to cease, to use the
products, goods or services of the business





     of the ATMI Group or of any ATMI Group  Subsidiary,  (2) has  substantially
reduced,  or currently  intends to  substantially  reduce,  the use of products,
goods  or  services  of the  business  of the ATMI  Group  or of any ATMI  Group
Subsidiary,  or (3) other  than in the  ordinary  course of  business  and to an
extent which is not reasonably  likely to have an ATMI Material  Adverse Effect,
has sought, or is seeking,  to reduce the price it will pay for products,  goods
or services of the  business of the ATMI Group or of any ATMI Group  Subsidiary.
Neither the ATMI Group nor any ATMI Group  Subsidiary has received any notice or
has any knowledge  that any of the ten (10) largest  suppliers of the ATMI Group
and the ATMI  Group  Subsidiaries  taken as a whole in terms of  purchases  made
during the 1995 and 1996  fiscal  years will not sell raw  materials,  supplies,
merchandise  and other  goods to the  business  of the ATMI Group or of any ATMI
Group  Subsidiary  at any time after the  Closing  Date on terms and  conditions
similar to those used in the current sales to the  business,  subject to general
and customary price increases and unforeseeable supply or demand changes.

4.27. Product and Service Warranties. To the knowledge of the ATMI Group:

     (a) All products sold and all services  rendered by the ATMI Group and each
ATMI Group Subsidiary have been in conformity in all material  respects with all
applicable  ATMI  Commitments  and all  expressed  warranties,  and no  material
liability exists or will arise for replacement or damage in connection with such
sales or for  services  not  rendered in all  material  respects  in  accordance
therewith.

     (b)  There is  adequate  provision  in the ATMI  Financial  Statements  for
liabilities  and  obligations  for damaged,  defective or returned goods, or for
replacement  of goods or for  allowances  with respect to goods sold or services
rendered by or on behalf of the ATMI Group or any ATMI Group Subsidiary.

     (c) Neither the ATMI Group nor any ATMI Group Subsidiary has any pattern of
claims or actions based upon  allegations of the same or similar  product defect
for any of its products.

     (d) There has not been any  material  product  recall,  rework or  retrofit
relating to any line of product manufactured,  shipped or sold by the ATMI Group
or any ATMI Group  Subsidiary,  nor to the  knowledge of the ATMI Group is there
any basis for any such product recall, rework or retrofit.

     4.28.  No Prior  Activities.  Holdings and Newco were formed solely for the
purpose of engaging in the  transactions  contemplated by this Agreement.  As of
the date hereof and the Effective  Time,  except for  obligations or liabilities
incurred  in  connection  with  its   incorporation   or  organization  and  the
transactions  contemplated  by this  Agreement and except for this Agreement and
any other  agreements or arrangements  contemplated  by this Agreement,  neither
Holdings nor Newco has nor will have incurred,  directly or indirectly,  through
any  subsidiary  or  affiliate  (other  than its  parent),  any  obligations  or
liabilities or engaged in any business activities of any type or kind whatsoever
or entered into any agreements or arrangements with any person.

     4.29.  Hart-Scott-Rodino.  The "total assets" and the "annual net sales" of
the  "ultimate  parent  entity"  (as such terms are used  within the  meaning of
Section  7A.(a)(2)(A) of the  Hart-Scott-Rodino  Antitrust  Improvements  Act of
1976) of the ATMI Group are less than $100,000,000.

     4.30. Finders' Fees. There is no investment banker, broker, finder or other
intermediary  that has been retained by or is authorized to act on behalf of the
ATMI  Group or any ATMI Group  Subsidiary  who might be  entitled  to any fee or
commission  from the ADCS Group or any other  person  upon  consummation  of the
transactions contemplated by this Agreement.

     4.31. Information in Disclosure Documents and Registration Statement.  None
of the information  made available or to be made available by the ATMI Group for
inclusion or incorporation by reference in (i) any registration  statement filed
in connection with this Agreement will, at the time such registration  statement
is filed with the SEC and at the time it becomes  effective under the Securities
Act,  contain  any  untrue  statement  of a  material  fact or omit to state any
material fact required to be stated therein or necessary to make the statements





     therein,  in light of the  circumstances  under  which  they are made,  not
misleading and (ii) the Proxy Statement will, at the date mailed to stockholders
and at the time of the meeting of stockholders to be held in connection with the
Merger,  contain any untrue  statement  of a material  fact or omit to state any
material  fact  required to be stated  therein or necessary in order to make the
statements therein, in light of the circumstances under which they are made, not
misleading.  The Proxy Statement will comply as to form in all material respects
with  the  provisions  of  the  Exchange  Act  and  the  rules  and  regulations
thereunder,  and  any  registration  statement  will  comply  as to  form in all
material  respects with the  provisions of the  Securities Act and the rules and
regulations thereunder,  except that no representation is made by the ATMI Group
with respect to statements  made therein based on information  made available by
the ADCS Group,  any ADCS Group  Subsidiary  or any Holder for  inclusion in any
registration statement or the Proxy Statement.

     4.32. Pooling. To its knowledge, the ATMI Group has not taken, or failed to
take, any action that would jeopardize the treatment of the  Reorganization as a
"pooling of interests" for accounting purposes.

     4.33. Section 203 of the DGCL. The Exchange by the Holders of each of their
Interests  for their Pro Rata  Portion of the  Exchange  Consideration  has been
approved by the Board of  Directors  of Holdings for the purposes of Section 203
of the DGCL.

     4.34. No  Misrepresentation.  Neither this Agreement nor any certificate or
Schedule or other  information  furnished  pursuant to this  Agreement  by or on
behalf  of the ATMI  Group or any ATMI  Group  Subsidiary  contains  any  untrue
statement  of a material  fact or, when this  Agreement  and such  certificates,
Schedules and other  information are taken in their  entirety,  omits to state a
material  fact  required to be stated  herein or therein  necessary  to make the
statements contained herein or therein not misleading.

                                    ARTICLE V

                                    Covenants

     5.1. Access to Information.  From the date hereof to the Closing Date, each
party will (i) afford to the officers, independent certified public accountants,
legal  counsel and other  representatives  of the other  parties,  during normal
business  hours,  reasonable  access  to  its  properties,  books,  records  and
personnel  in order  that  each  party may have  full  opportunity  to make such
investigation  as  it  reasonably   desires  to  make  in  connection  with  the
transactions  contemplated herein; (ii) confer with representatives of the other
parties;  (iii) furnish to the other parties,  either orally or by means of such
records,  documents,  and memoranda as are  available or  reasonably  capable of
preparation,  such information as the other parties may reasonably request;  and
(iv) furnish to the other parties' auditors all consents and authority that they
may reasonably  request in connection  with any examination of each party by the
other parties.  The rights  pursuant to this Section 5.1 shall be subject to the
provisions of the Confidentiality  Agreement dated October 22, 1996 between ADCS
LP and ATMI,  which  Confidentiality  Agreement  shall be binding on each of the
ADCS  Group and each of the ATMI  Group  and shall  survive  the  execution  and
delivery of and the termination of, this Agreement.

     5.2. Interim Operations of ADCS Group.  Except as set forth on Schedule 5.2
and as provided in Section 5.21, the ADCS Group hereby covenants and agrees that
between the date  hereof and the  Closing,  and unless the ATMI Group  otherwise
consents in advance in writing:

     (a) The ADCS  Group  and each  ADCS  Group  Subsidiary  shall  conduct  its
business in the ordinary course and in accordance  with its past practices,  and
use its diligent efforts to (i) preserve its business organization intact, (ii)

     preserve  its goodwill and the  confidentiality  of its business  know-how,
(iii)  keep  available  to the ADCS  Group and each ADCS  Group  Subsidiary  the
services of its present key employees and those material to the operation of its
respective  business,  and (iv) preserve the present  relationships  between the
ADCS Group or




     any ADCS  Group  Subsidiary  and its  collaborators,  licensors  and others
having business relations with the ADCS Group or any ADCS Group Subsidiary.

     (b) The ADCS  Group  and each  ADCS  Group  Subsidiary  shall  conduct  its
business  only in the usual  and  ordinary  manner  and  shall  not  change  the
character of its business.

     (c) Neither the ADCS Group nor any ADCS Group  Subsidiary  shall authorize,
amend the terms of,  issue or contract  for the  issuance  of or grant  options,
warrants or rights to purchase any ADCS Group Securities.

     (d) The ADCS Group  shall use its best  efforts to cause the Holders not to
transfer any of the Interests, other than transfers to family members and trusts
for their benefit or involuntary transfers,  which in any event do not adversely
affect the pooling of interests treatment of the Reorganization.  The ADCS Group
will give ATMI prompt written  notice of any such transfer.  Each such permitted
transferee shall be deemed a "Holder" for all purposes of this Agreement.

     (e)  Neither  the ADCS  Group nor any ADCS Group  Subsidiary  shall pay any
dividend or make any other  distribution  with respect to or repurchase or agree
to repurchase any ADCS Group Securities.

     (f) The ADCS Group and each ADCS Group Subsidiary shall (i) use and operate
substantially all of its assets in the ordinary course of business in accordance
with  past   practices  and  maintain   substantially   all  of  its  assets  in
substantially  the same  condition  as they are now  (reasonable  wear and tear,
which  are not such as to  adversely  affect  the  operation  of such  business,
excepted);  (ii) maintain  insurance  upon all of its assets and with respect to
the conduct of its  business,  all such  insurance to be  comparable  in amount,
scope and  coverage to that in effect on the date of this  Agreement;  and (iii)
give ATMI prompt written notice of any material damage to its properties by fire
or other casualty.

     (g) The ADCS Group and each ADCS Group Subsidiary shall maintain its books,
records and accounts in the ordinary course consistent with past practice,  on a
basis consistent with prior periods,  and shall not make any material changes in
the accounting methods or practices followed by the ADCS Group or any ADCS Group
Subsidiary or any change in the  depreciation or amortization  policies or rates
theretofore adopted or applied.

     (h) The ADCS Group and each ADCS Group  Subsidiary shall duly comply in all
material  respects with all laws applicable to it, its assets and the conduct of
its business.

     (i) The ADCS Group and each ADCS Group  Subsidiary shall perform all of its
material obligations under the ADCS Commitments without default.

     (j)  Except  in the  ordinary  course  of  business  consistent  with  past
practice,  neither the ADCS Group nor any ADCS Group  Subsidiary shall grant any
power of attorney with respect to its business or assets.

     (k)  Except  in the  ordinary  course  of  business  consistent  with  past
practice,  neither the ADCS Group nor any ADCS Group Subsidiary shall enter into
any new ADCS Commitments,  or cancel, amend, modify adversely,  assign, encumber
or  terminate  any  of  the  ADCS  Commitments  or  make  any  material  capital
investment,  expenditure or  improvement  or enter into any agreement  therefor,
which in any  event  would be  material  to the ADCS  Group  and the ADCS  Group
Subsidiaries taken as a whole.

     (l)  Except  in the  ordinary  course of  business  and to the  extent  not
material  to the ADCS  Group and the ADCS Group  Subsidiaries  taken as a whole,
neither the ADCS Group nor any ADCS Group Subsidiary shall (i) make any loan, or
otherwise  extend  credit  to any  person,  firm or  corporation,  except in the
ordinary  course of business and consistent  with the past practices of the ADCS
Group or any ADCS Group  Subsidiary,  (ii) give any guarantee or  indemnity,  or
make any other similar  commitment  with respect to a debt or other liability of
any person, firm or corporation, or (iii) (excluding transactions among the ADCS
Group and the ADCS Group





     Subsidiaries) create, incur or otherwise become liable for any indebtedness
(other  than  interest  and fees  assessed  on the  outstanding  portion of such
indebtedness),  or otherwise  subject any of its property or assets to any lien,
security interests, encumbrance or charge.

     (m)  Neither  the ADCS Group nor any ADCS Group  Subsidiary  shall make any
payment in excess of $50,000,  except for payment of liabilities incurred in the
ordinary  course of  business,  and the payment of the fees and  expenses of its
attorneys  and  accountants   incurred  in  connection  with  the   transactions
contemplated hereby.

     (n) Neither the ADCS Group nor any ADCS Group  Subsidiary shall sell, lease
or  otherwise  dispose of any of the assets,  except in the  ordinary  course of
business for a cash  consideration  which equals a fair value at the time of the
sale of any of the assets.

     (o)  Except  in the  ordinary  course  of  business  consistent  with  past
practice,  neither the ADCS Group nor any ADCS Group  Subsidiary shall (i) grant
any severance or termination pay to any director,  officer, employee, partner or
member of the ADCS  Group or any ADCS  Group  Subsidiary;  (ii)  enter  into any
employment,  severance,  management,  consulting, deferred compensation or other
similar  agreement (or any amendment to any such  existing  agreement)  with any
director,  officer,  employee,  partner  or member of the ADCS Group or any ADCS
Group  Subsidiary;  (iii) change  benefits  payable under existing  severance or
termination  pay policies or employment,  severance,  management,  consulting or
other similar  agreements other than normal yearly  adjustments;  or (iv) change
compensation,  bonus or other benefits payable to director,  officer,  employee,
partner  or member of the ADCS Group or any ADCS  Group  Subsidiary,  other than
normal yearly adjustments, other than promotions made in the ordinary course and
other than any increase pursuant to any ADCS Employee Benefit Plan, the formulae
or commission rates of which have not been amended or changed.

     (p) The ADCS Group will use its best efforts not to authorize or permit (i)
the ADCS Organizational Documents to be amended; (ii) the merger,  consolidation
or other  combination  of the ADCS Group or any ADCS Group  Subsidiary  with any
other entity; or (iii) the ADCS Group or any ADCS Group Subsidiary to organize a
subsidiary.

     (q) The ADCS Group  shall not take any action  which would  jeopardize  the
treatment of the Reorganization as a tax-free transaction or which would prevent
the Reorganization from being accounted for as a pooling of interests.

     5.3.  Interim  Operation of the ATMI Group. The ATMI Group hereby covenants
and agrees that  between the date  hereof and the  Closing,  and unless the ADCS
Group otherwise consents in advance in writing:

     (a) The ATMI  Group  and each  ATMI  Group  Subsidiary  shall  conduct  its
business in the ordinary course and in accordance  with its past practices,  and
use its diligent efforts to (i) preserve its business  organization intact, (ii)
preserve its goodwill and the  confidentiality of its business  know-how,  (iii)
keep available to the ATMI Group and each ATMI Group  Subsidiary the services of
its present key employees and those  material to the operation of its respective
business,  and (iv) preserve the present relationships between the ATMI Group or
any ATMI Group  Subsidiary  and its  collaborators,  licensors and others having
business relations with the ATMI Group or any ATMI Group Subsidiary.

     (b) The ATMI  Group  and each  ATMI  Group  Subsidiary  shall  conduct  its
business  only in the usual  and  ordinary  manner  and  shall  not  change  the
character of its business.

     (c)  Neither  the ATMI  Group nor any ATMI Group  Subsidiary  shall pay any
dividend or make any other  distribution  with respect to or repurchase or agree
to repurchase any ATMI Group Securities.

     (d) The ATMI Group and each ATMI Group Subsidiary shall (i) use and operate
substantially all of its assets in the ordinary course of business in accordance
with past practices and maintain substantially all of its





     assets in substantially the same condition as they are now (reasonable wear
and tear,  which  are not such as to  adversely  affect  the  operation  of such
business, excepted); (ii) maintain insurance upon the assets and with respect to
the conduct of its  business,  all such  insurance to be  comparable  in amount,
scope and  coverage to that in effect on the date of this  Agreement;  and (iii)
give  the ADCS  Group  prompt  written  notice  of any  material  damage  to its
properties by fire or other casualty.

     (e) The ATMI Group and each ATMI Group Subsidiary shall maintain its books,
records and accounts in the ordinary course consistent with past practice,  on a
basis consistent with prior periods,  and shall not make any material changes in
the accounting methods or practices followed by the ATMI Group or any ATMI Group
Subsidiary or any change in the  depreciation or amortization  policies or rates
theretofore adopted or applied.

     (f) The ATMI Group and each ATMI Group  Subsidiary shall duly comply in all
material  respects with all laws applicable to it, its assets and the conduct of
its business.

     (g) The ATMI Group and each ATMI Group  Subsidiary shall perform all of its
material obligations under the ATMI Commitments without default.

     (h) Neither the ATMI Group nor any ATMI Group  Subsidiary shall sell, lease
or  otherwise  dispose of any of the assets,  except in the  ordinary  course of
business for a cash  consideration  which equals a fair value at the time of the
sale of any of the assets.

     (i) The ATMI Group will use its best  efforts  not to  authorize  or permit
with respect to ATMI,  and will not authorize or permit with respect to any ATMI
Subsidiary,  (i) the ATMI  Organizational  Documents to be amended,  or (ii) the
merger,  consolidation or other  combination of the ATMI Group or any ATMI Group
Subsidiary  with any other  entity,  except as may be  necessary  to effect  any
acquisitions  made by ATMI,  subject to its obligations under Section 5.5, or to
change the name of any member of the ATMI Group.

     (j) The ATMI Group  shall not take any action  which would  jeopardize  the
treatment of the Reorganization as a tax-free transaction or which would prevent
the Reorganization from being accounted for as a pooling of interests.

     (k) The ATMI Group shall not grant to any other party  piggyback  or demand
registration  rights  which  are pari  passu or  greater  in  priority  than the
registration rights to be provided pursuant to the Registration Rights Agreement
attached hereto as EXHIBIT C (the "Registration Rights Agreement").

     (l) The ATMI Group will not amend its stock option, stock purchase or other
similar  equity-based  incentive  compensation  plans to increase  the number of
shares of stock issuable thereunder, nor issue shares of its capital stock which
would cause the number of its shares of capital stock to be more than the number
of shares that are issued and outstanding as of the date hereof,  except (i) the
ATMI Group may approve and issue  options  under  ATMI's  existing  stock option
plans, (ii) the ATMI Group may approve a new stock option plan for up to 900,000
shares of Holdings  Common Stock,  (iii) pursuant to the exercise of Outstanding
ATMI Options,  Outstanding ATMI Warrants and options  hereafter issued under (i)
above,  and (iv) in connection with  acquisitions  made by ATMI,  subject to its
obligations under Section 5.5.

     (m)  Except  in the  ordinary  course  of  business  consistent  with  past
practice,  neither the ATMI Group nor any ATMI Group Subsidiary shall enter into
any new ATMI Commitments,  or cancel, amend, modify adversely,  assign, encumber
or  terminate  any  of  the  ATMI  Commitments  or  make  any  material  capital
investment,  expenditure or  improvement  or enter into any agreement  therefor,
which in any  event  would be  material  to the ATMI  Group  and the ATMI  Group
Subsidiaries taken as a whole.

     (n)  Except  in the  ordinary  course of  business  and to the  extent  not
material  to the ATMI  Group and the ATMI Group  Subsidiaries  taken as a whole,
neither the ATMI Group nor any ATMI Group Subsidiary shall





     (i) make any  loan,  or  otherwise  extend  credit to any  person,  firm or
corporation,  except in the ordinary  course of business and consistent with the
past  practices  of the ATMI Group or any ATMI Group  Subsidiary,  (ii) give any
guarantee or indemnity,  or make any other similar  commitment with respect to a
debt or other liability of any person, firm or corporation,  or (iii) (excluding
transactions among the ATMI Group and the ATMI Group Subsidiaries) create, incur
or otherwise  become liable for any  indebtedness  (other than interest and fees
assessed on the outstanding portion of such indebtedness),  or otherwise subject
any of its property or assets to any lien,  security  interests,  encumbrance or
charge.

     (o)  Neither  the ATMI Group nor any ATMI Group  Subsidiary  shall make any
payment in excess of $100,000, except for payment of liabilities incurred in the
ordinary  course of  business,  and the payment of the fees and  expenses of its
attorneys  and  accountants   incurred  in  connection  with  the   transactions
contemplated hereby.

     (p)  Except  in the  ordinary  course  of  business  consistent  with  past
practice,  neither the ATMI Group nor any ATMI Group  Subsidiary shall (i) grant
any severance or termination pay to any director,  officer, employee, partner or
member of the ATMI Group or any ATMI Group Subsidiary;  (ii) except as described
in  Schedule  5.3(p),   enter  into  any  employment,   severance,   management,
consulting,  deferred  compensation or other similar agreement (or any amendment
to any such existing agreement) with any director, officer, employee, partner or
member of the ATMI Group or any ATMI Group  Subsidiary;  (iii)  change  benefits
payable under  existing  severance or  termination  pay policies or  employment,
severance, management,  consulting or other similar agreements other than normal
yearly adjustments; or (iv) change compensation, bonus or other benefits payable
to director,  officer, employee, partner or member of the ATMI Group or any ATMI
Group Subsidiary,  other than normal yearly  adjustments,  other than promotions
made in the  ordinary  course and other than any  increase  pursuant to any ATMI
Employee  Benefit Plan, the formulae or commission  rates of which have not been
amended or changed.

     5.4.  Notices of Certain Events.  From the date hereof to and including the
Closing Date, the ADCS Group and the ATMI Group covenant and agree to notify the
other of (i) any notice or other communication from any person alleging that the
consent of such person is or may be required in connection with the transactions
contemplated by this Agreement;  (ii) any notice or other communication from any
foreign or domestic  governmental  authority in connection with the transactions
contemplated  by this  Agreement;  and (iii) any matter  arising and  discovered
after the date of this Agreement  that, if existing or known on the date of this
Agreement,  would have been required to be disclosed pursuant to this Agreement,
or that  constitutes  a breach or  prospective  breach of this  Agreement by the
notifying party or its affiliates.

     5.5.  Other  Acquisitions  by ATMI.  From and after the date  hereof to the
Effective Time or the  termination of this Agreement in accordance  with Article
IX, without first giving the ADCS Group notice thereof, ATMI will not enter into
a definitive  agreement with respect to any acquisition having a value in excess
of $18,000,000 (including the value of (i) cash, stock and assets transferred as
consideration in any acquisition, whether by way of merger, purchase or exchange
or otherwise; (ii) options, warrants or convertible securities issued or assumed
in  connection  with such  acquisition;  and  (iii) any debt or other  liability
issued  or  assumed  in  connection  with  such  acquisition).  The  information
contained  in such  notice  shall be  subject to the  restrictions  set forth in
Sections  5.1 and 5.6.  The ADCS  Group  shall  have the right  within  ten (10)
business  days after  notice is given by ATMI to notify ATMI that the ADCS Group
objects  to such  acquisition  and  indicating  the  reasonable  basis  for such
objection.  Failure of the ADCS Group to give notice  within such 10-day  period
shall waive the ADCS  Group's  right to object.  Within five (5)  business  days
after ATMI's receipt of the ADCS Group's notice of objection,  ATMI shall notify
the ADCS Group of ATMI's  intention  to either  terminate  or proceed  with such
acquisition.  If ATMI indicates its intention to proceed with such  acquisition,
the ADCS Group shall have the right,  exercisable  within five (5) business days
after its receipt of ATMI's notice of its intent to proceed,  to terminate  this
Agreement  pursuant to Section  9.1(d)(ii)  without any liability on the part of
any party hereto.





     5.6. No Public Disclosure. The ADCS Group understands that ATMI is a public
company, and that until the transactions contemplated by this Agreement are made
public,  the ADCS  Group  and the  Holders  and those  whom they  advise of this
transaction  (which  shall  only be on a "need to know  basis")  may be privy to
material inside information;  accordingly,  the ADCS Group understands,  and the
ADCS Group has apprised those of its officers,  members, partners and agents who
know of the  potential  transaction,  of the  need for  confidentiality  and the
potential  consequences of any trading in the ATMI Group  Securities.  No public
announcements  shall be made  concerning the  negotiations  between the parties,
this Agreement or the transactions contemplated herein, without the prior mutual
consent  of the ADCS  Group and ATMI,  except as may be  required  by law or the
rules or regulations of The Nasdaq National Market; provided that ATMI shall use
its best efforts to obtain ADCS' mutual consent to the timing and content of any
such announcements. The parties agree that, to the maximum extent feasible, they
will  advise and confer with each other  prior to the  issuance of any  reports,
statements  or  releases  pertaining  to  this  Agreement  or  the  transactions
contemplated herein. In addition,  the parties agree to respond to all inquiries
with  respect to the  Reorganization  by stating  that it is their policy not to
comment on such matters.

     5.7. No  Negotiation.  The ADCS Group and each ADCS Group  Subsidiary  will
not,  and the ADCS  Group will use best  efforts  to cause  each  Holder not to,
directly or indirectly,  solicit,  discuss,  or engage in negotiations  with, or
provide  information  to, any person,  other than ATMI,  concerning any possible
proposal regarding the acquisition of the Interests,  the ADCS Group or any ADCS
Group Subsidiary or any part thereof, or any merger or consolidation thereof, or
accept any such proposal.

     5.8.  NovaMOS.  Following  the Closing,  the NovaMOS  division and the ADCS
Group shall be operated as set forth on SCHEDULE 5.8.

     5.9. Election of Directors.  Holdings shall, as of the Closing Date, have a
vacancy  on its six (6) person  Board of  Directors  for the class of  directors
elected for a  three-year  term and shall,  on the day after the  Closing  Date,
appoint  Stephen H.  Siegele to fill such  vacancy.  To the extent  permitted by
applicable law,  Holdings shall cause the Board of Directors to nominate Stephen
H. Siegele or his  designee to serve for an  additional  three-year  term and to
support  his or her  nomination  to the same extent and in the same manner as it
supports other nominees on the slate of directors proposed by Holdings, provided
that at the time of such  nomination  by the  Board the  Exchange  Consideration
owned of record by the Holders  represents in the aggregate ten percent (10%) or
more of the shares of Holdings Common Stock then outstanding.

     5.10.  HSR Act. In the event that the parties  determine  that the proposed
transactions  are  subject  to a  waiting  period  under  the  Hart-Scott-Rodino
Antitrust  Improvements  Act of 1976, as amended (the "HSR Act"), the ADCS Group
and the ATMI Group shall  promptly file or cause to be filed on behalf of itself
and any  other  acquired  or  acquiring  persons  under  the HSR Act,  Premerger
Notification  and Report  Forms with  respect to the  transactions  contemplated
herein,  respond to any requests for  additional  information  and documents and
provide the necessary  information and make the necessary  filings under the HSR
Act.  The Closing  Date shall be  reasonably  extended as necessary to allow the
period  specified in the HSR Act and any  extensions  thereof to expire prior to
such date.  The ATMI Group shall pay all  applicable HSR filing fees of the ADCS
Group, the Holders and their respective affiliates.

     5.11.  Preparation  of S-4 and the Proxy  Statement.  The ATMI Group  shall
prepare  and  file as  promptly  as  practicable  after  the  execution  of this
Agreement with the SEC a confidential  preliminary  Proxy Statement with respect
to the Reorganization which complies in form with applicable requirements of the
SEC. As promptly as practicable after the receipt of any comment letter from the
staff of the SEC,  ADCS and ATMI shall  cooperate  in the  response  to any such
comment  letter,  or, in any event and if no such letter is received,  shall use
all reasonable  efforts to cause the S-4 to become  effective as soon thereafter
as  practicable.  The ATMI  Group  shall  use its best  efforts  to have the S-4
declared  effective  under the Securities  Act as promptly as practicable  after
such filing.  The ATMI Group shall take any action (other than  qualifying to do
business in any jurisdiction in which it is not now so qualified) required to be
taken under any applicable state securities laws in connection





     with the issuance of Holdings Common Stock in the  Reorganization,  and the
ADCS Group  shall  furnish  all  information  concerning  the ADCS Group and the
Holders as may be reasonably requested in connection with any such action.

     5.12. Best Efforts;  Cooperation.  The ADCS Group will use its best efforts
to cause the Holders to tender  their  Interests at the Closing and to cause the
other  conditions of Closing to be met by it, and ATMI will use its best efforts
to cause the other conditions of Closing to be met by it.

     5.13.  ATMI  Stockholder  Matters.   ATMI  shall  call  a  meeting  of  its
stockholders  for the purpose of voting upon matters  relating to this Agreement
and the  Reorganization to be held as soon as practicable after the SEC declares
the  S-4  effective.   ATMI  will  use  reasonable  best  efforts  to  hold  its
stockholders'  meeting as promptly as practicable  thereafter and will,  through
its  Board  of  Directors,  recommend  to  its  stockholders  approval  of  this
Agreement, the Reorganization and the other transactions  contemplated hereby or
thereby and will use its reasonable  best efforts to cause its  stockholders  to
approve   the   Merger.   In   addition,   the   ATMI   Group   may   retain   a
nationally-recognized  proxy solicitation firm if the ATMI Group in consultation
with the ADCS Group  deems such action to be  necessary  in order to receive the
approval of ATMI  stockholders  with  respect to the  transactions  contemplated
hereby.

     5.14.  Nasdaq  Listing.  ATMI and  Holdings  will make such  filings as are
necessary  with  the  NASD  and  The  Nasdaq  National   Market   regarding  the
transactions  contemplated  hereby and will use their best  efforts to cause the
shares  of  Holdings  Common  Stock to be  issued  in the  Reorganization  to be
approved for listing on The Nasdaq National  Market,  subject to official notice
of issuance, prior to the Effective Time.

     5.15.  Affiliates.  The ATMI  Group and the ADCS  Group  shall  deliver  to
Holdings  a  letter   identifying   all   persons  who  are,  at  the  time  the
Reorganization  is effected,  "affiliates"  of either the ATMI Group or the ADCS
Group.  The ATMI  Group  and the ADCS  Group  shall  cause  each  person  who is
identified as an  "affiliate"  in such letter to deliver to Holdings on or prior
to the Effective Time an Affiliates  Agreement,  in the form attached  hereto as
EXHIBIT D-1 with respect to  affiliates  of ADCS and EXHIBIT D-2 with respect to
affiliates of ATMI (the "Affiliates Agreements").

     5.16. Financial Statements and SEC Reports.  From and after the date hereof
until the Effective  Time, each party hereto shall deliver to the other, as soon
as available  but in no event later than  forty-five  (45) days after the end of
each fiscal  quarter,  a  consolidated  balance sheet as of the last day of such
fiscal period and a consolidated  statement of income,  stockholders' equity and
cash flows of such party and its  subsidiaries for the fiscal period then ended,
prepared in accordance with general accounting principles,  with such exceptions
as are  noted  on  such  financial  statements,  and in the  case of  ATMI,  the
requirements  of Form 10-Q or Form 10-K,  as the case may be, under the Exchange
Act. From and after the date hereof until the Effective Time, ATMI shall deliver
to the ADCS Group as soon as available  all forms,  reports and other  documents
filed by the ATMI Group or its  affiliates  with the SEC,  and each party  shall
otherwise  keep the other apprised of any material  development  with respect to
its business or financial condition.

     5.17.  Employee  Benefits.  (a) As of Closing Date,  ATMI or Holdings shall
provide all employees of the ADCS Group and each ADCS Group ERISA  Affiliate and
their  dependents,  and all  qualified  beneficiaries  (as  defined  in  Section
4980B(g)(1) of the Code) entitled to receive  continuation  coverage under COBRA
as of the Closing Date (the "Qualified  Beneficiaries")  with coverage under one
or more ATMI Benefit Plans (the "Successor Welfare Plans"),  including,  without
limitation,  health  care  coverage  ("Coverage"),  which  meets  at  least  the
following  requirements:  (i)  service  with the ADCS  Group and each ADCS Group
ERISA Affiliate prior to the Closing Date shall be credited  against all service
and waiting  period  requirements  under the  Successor  Welfare Plans for those
employees  of the ADCS  Group and each ADCS  Group  ERISA  Affiliate  (and their
eligible dependents) that received coverage from the ADCS Group or an ADCS-Group
ERISA Affiliate as of the Closing Date,  (ii) the Successor  Welfare Plans shall
not provide for any pre-existing  condition exclusion for those employees of the
ADCS Group and each ADCS Group ERISA  Affiliate (and their eligible  dependents)
and





     Qualified  Beneficiaries that were entitled to coverage from the ADCS Group
or an  ADCS  Group  ERISA  Affiliate  as of the  Closing  Date,  and  (iii)  the
deductibles  in effect under the  Successor  Welfare  Plans for the plan year in
which the Closing  Date occurs shall be reduced by any amounts  applied  towards
the  deductibles  under the ADCS Group  Benefit Plans for the plan year in which
the Closing  Date  occurs  provided  such  individuals  submit  evidence to ATMI
sufficient  to  demonstrate   the  amount  so  applied  against  any  applicable
deductibles  in effect  under any ADCS  Group  Benefit  Plan,  provided  ATMI or
Holdings  shall  only be  obligated  to  provide  Coverage  to  such  employees,
dependents and qualified  beneficiaries to the extent ATMI or Holdings  sponsors
the same type of Group  Benefit  Plans that the ADCS Group did as of the Closing
Date.

     (b) ATMI  covenants that the service of each employee of the ADCS Group and
each ADCS Group ERISA  Affiliate  prior to the Closing Date shall be credited as
service  under  the  ATMI  401(k)  Plan  for  all  purposes  (including  without
limitation,  eligibility  and vesting) for those employees of the ADCS Group and
each ADCS Group  ERISA  Affiliate  that were  participants  in any  401(k)  plan
maintained by the ADCS Group or an ADCS Group ERISA  Affiliate as of the Closing
Date.

     (c) The parties  recognize that the ADCS Group's forms of  compensation  of
its employees,  consultants and directors have differed from ATMI's,  including,
but not limited to, in the  payment of cash  versus  equity-based  compensation.
ATMI will use  reasonable  efforts  prior to Closing to obtain the ADCS  Group's
agreement to the amount and types of compensation to be paid to employees of the
ADCS Group commencing as of the Closing.  Nothing herein shall confer any rights
upon any such employees.

     5.18.  Tax Matters.  Each of the parties agrees to prepare and file any and
all tax returns,  reports and other  filings  regarding the tax treatment of the
Reorganization  in a manner which is  consistent in all respects with the intent
and  expectation  set forth in Section 2.6 above.  Each of the  parties  further
agrees to use  reasonable  efforts not to do any act or thing,  before or at any
time after the Reorganization,  which would cause the Reorganization not to be a
transaction  described in Section 351 of the Code. The ATMI Group agrees that it
will not  take any tax  position  contrary  to,  or in  conflict  with,  any tax
position taken in good faith prior to the Closing by a member of the ADCS Group,
any  ADCS  Group  Subsidiary,  or  any  predecessor  in  interest  to any of the
foregoing, or any Holder.

     5.19.  Supplements to Disclosure  Schedules.  Without limiting the parties'
obligations under Section 5.4, from time to time prior to the Closing,  the ATMI
Group and the ADCS  Group  will  promptly  supplement  or amend  the  respective
disclosure  schedules which they have delivered  pursuant to this Agreement with
respect to any matter  hereafter  arising which, if existing or occurring at the
date of this Agreement, would have been required to be set forth or described in
any such disclosure schedule or which is necessary to correct any information in
any such  disclosure  schedule which has been rendered  inaccurate  thereby.  No
supplement or amendment to any such  disclosure  schedule  shall have any effect
for the  purpose of  determining  satisfaction  of the  conditions  set forth in
Sections 6.l(a) or 6.2(a) of this Agreement.

     5.20.  Expenses.  In the  event  the  Reorganization  is  consummated,  the
reasonable  legal and  accounting  costs (for all of which an estimate  shall be
given to the ATMI  Group on the date  hereof)  will be borne by the ATMI  Group;
otherwise,  in the event the Reorganization is not consummated,  each party will
bear its own costs and expenses.  Whether or not the transaction is consummated,
the  ATMI  Group  shall  pay all SEC  registration,  HSR  and  other  applicable
governmental   filing  fees  incurred  in  connection   with  the   negotiation,
preparation  and execution of this  Agreement and the  performance of any of the
obligations contemplated hereby or thereby.

     5.21. Officer and Director Indemnity.  (a) Simultaneously with the Closing,
the ADCS  Organizational  Documents shall be amended to the extent  necessary to
provide the same level of indemnification for the current directors and officers
and  employees  of the ADCS Group (each,  a "Current  ADCS  Indemnitee")  as the
bylaws of ATMI provide on the date hereof for directors,  officers and employees
of ATMI.  Holdings  will not  permit  the ADCS  Organizational  Documents  to be
amended to affect  adversely the  provisions  concerning  indemnification  for a
Current ADCS Indemnitee;  provided, however, that Holdings reserves the right to
liquidate, dissolve,





     consolidate,  reorganize  or merge any entity within the ADCS Group so long
as any successor(s)  expressly  assumes and agrees to perform the obligations of
indemnity set forth in such ADCS Organizational Documents in the same manner and
to the same extent that the  predecessor  entity would be required to perform if
no such succession had taken place,  and each Current ADCS  Indemnitee  shall be
entitled to enforce such obligations of indemnity  against any such successor(s)
to the same extent and with the same force and effect as if such  successor  was
originally a party hereto.

     (b)  Holdings  agrees  that  in the  event  that  the  ATMI  Organizational
Documents are at any time amended so that the provisions therein relating to the
indemnification  of directors,  officers or employees of the ATMI Group are less
favorable than those currently contained therein, that Holdings will first agree
with any  Current  ADCS  Indemnitee,  who at any time is or becomes a  director,
officer or employee of Holdings, ATMI, or any subsidiary thereof, to provide for
rights to  indemnification  no less  favorable  than those in effect on the date
hereof.

     5.22.  Exchange  Act Section  16(b).  The ATMI Group shall take no position
inconsistent  with the positions taken by any Holders with respect to a "Section
16(b)  Matter" after the date hereof that will or may,  directly or  indirectly,
whether taken alone or together  with other facts or events,  result in a Holder
or any affiliate of a Holder having  "Section 16(b)  Liability." As used herein,
the following terms shall have the respective meanings set forth below:

     "Section  16(b)  Liability"  means  liability  under  Section  16(b) of the
Exchange Act with respect to or as a consequence, directly or indirectly, of (i)
a Holder's  or  Holder's  affiliate's  acquisition  (or deemed  acquisition)  of
"beneficial  ownership"  of, or a "pecuniary  interest"  or "indirect  pecuniary
interest"  in, any of the Exchange  Consideration  that shall have been acquired
(or  deemed to have  been  acquired)  pursuant  to this  Agreement;  or (ii) any
dispute with respect to the date on which any Holder becomes  subject to Section
16 of the Exchange Act, if at all, pursuant to this Agreement.

     "Section  16(b) Matter" means each matter or series of matters  (including,
without limitation,  a proposed transaction or series of transactions  involving
any   stock  or   other   non-cash   dividend,   split-up,   reverse   split-up,
reclassification,  recapitalization,  reorganization,  combination, subdivision,
conversion,  exchange of shares or  acquisition,  merger or other  similar  such
transaction),  which, directly or indirectly,  as a result of the taking of such
action by Holdings,  its Board of Directors or stockholders or any  governmental
authority having  jurisdiction  thereover,  or the conclusion of any such matter
will or may, directly or indirectly,  whether taken alone or together with other
facts or events, result in Section 16(b) Liability.

     5.23.  Environmental Report. The ATMI Group has at its expense ordered from
GZA GeoEnvironmental,  Inc. a Phase II environmental site assessment of the ADCS
manufacturing site in Burnet,  Texas. The ATMI Group will use reasonable efforts
to have the assessment  completed no later than April 28, 1997.  Within ten (10)
days after its receipt  thereof,  the ATMI Group shall  deliver to ADCS Nevada a
copy of the  assessment,  together  with a written  statement  from ATMI stating
whether or not (i) the assessment  indicates an  Environmental  Condition  which
ATMI in good faith has determined  could have an ADCS Material Adverse Effect (a
"Material  Environmental  Condition"),  and  (ii)  the  ATMI  Group  intends  to
terminate this Agreement as a result of such Material  Environmental  Condition.
If the ATMI Group states its intention to terminate  this  Agreement as a result
of a Material  Environmental  Condition,  this  Agreement  will terminate on the
thirtieth  (30th) day after ADCS  Nevada's  receipt of such notice unless within
such  30-day  period  the  ADCS  Group  successfully  remediates  such  Material
Environmental  Condition or the parties agree  otherwise.  If this  Agreement is
terminated  pursuant to this Section 5.23,  the ATMI Group shall not be entitled
to a termination  payment under Section 9.2. If this Agreement is not terminated
pursuant to this Section 5.23, then the results of such Phase II site assessment
shall be deemed to be incorporated  into the ADCS Disclosure  Schedule as of the
date on which this Agreement is executed.




                                   ARTICLE VI

                         Conditions Precedent to Closing

     6.1. Conditions to the Obligations of the ATMI Group. The obligation of the
ATMI Group to  consummate  the Merger,  the Exchange and the other  transactions
contemplated  hereby  shall be subject to the  satisfaction,  on or prior to the
Closing Date, of each of the following conditions (any of which may be waived in
writing by the ATMI Group in its sole discretion):

     (a) Representations and Warranties True. The representations and warranties
of the ADCS Group and the Holders  which are  contained  in this  Agreement,  or
contained in any Schedule, certificate or other instrument or document delivered
or to be delivered pursuant to this Agreement,  shall be true and correct in all
material  respects on and as of the Closing Date as though such  representations
and warranties were made on and as of the Closing Date, except for the effect of
any activities or transactions which may have taken place after the date of this
Agreement expressly  permitted by this Agreement,  incident to carrying out this
Agreement,  or consented to in writing by ATMI.  At the Closing,  the ADCS Group
shall have  delivered to the ATMI Group a certificate  confirming  the foregoing
(signed  on  behalf  of the  ADCS  Group  by  the  President,  General  Partner,
authorized member, etc., as appropriate).

     (b)  Performance.  The ADCS Group shall have  performed and complied in all
material  respects with all of the  obligations  under this Agreement  which are
required to be performed or complied with by it on or prior to the Closing Date.
At the  Closing,  the ADCS  Group  shall  have  delivered  to the  ATMI  Group a
certificate  confirming the foregoing (signed on behalf of the ADCS Group by the
President, General Partner, authorized member, etc., as appropriate).

     (c)  Stockholder  Approval.  This  Agreement  and the  consummation  of the
transactions  contemplated  herein shall have been duly  approved and adopted by
the stockholders of ATMI in accordance with the DGCL and the ATMI Organizational
Documents.

     (d) Absence of Litigation.  No statute,  rule or regulation shall have been
enacted or promulgated, and no order, decree, writ or injunction shall have been
issued and shall remain in effect,  by any court or  governmental  or regulatory
body,  agency or authority which restrains,  enjoins or otherwise  prohibits the
consummation of the transactions  contemplated  hereby,  and no action,  suit or
proceeding  before  any court or  governmental  or  regulatory  body,  agency or
authority   shall  have  been  commenced   with  respect  to  the   transactions
contemplated hereby or with respect to the ADCS Group, any ADCS Group Subsidiary
or any  Holder  not set forth in a  Schedule  hereto  which,  in the  reasonable
judgment  of the  ATMI  Group,  would  have a  material  adverse  effect  on the
transactions contemplated hereby or an ADCS Material Adverse Effect.

     (e) Pooling of Interests. The ATMI Group shall have received a letter dated
as of the Effective Time from Ernst & Young LLP, independent  accountants to the
ADCS  Group and the ATMI  Group,  regarding  the  appropriateness  of pooling of
interest  accounting for the  Reorganization  under Accounting  Principles Board
Opinion No. 16.

     (f)  Additional  Agreements.  The ADCS  Group and the  Holders  shall  have
delivered (or cause to be delivered) duly executed counterparts of the following
agreements:

     (i) Proprietary Information and Inventions Agreements. The ADCS Group shall
have used best  efforts to cause each  employee  of the ADCS Group and each ADCS
Group  Subsidiary  to have entered into ATMI's  customary  Employee  Proprietary
Information  and  Inventions   Agreements  (the  "Proprietary   Information  and
Inventions  Agreements") with ATMI and/or the ADCS Group, as ATMI may determine,
a copy of which is attached hereto as EXHIBIT E.





     (ii)  Employment  Agreements.  Each of Stephen  H.  Siegele,  Frederick  H.
Siegele,  and  Frederick  J.  Siegele  shall  have  entered  into an  Employment
Agreement (each an "Employment  Agreement")  with ATMI and/or the ADCS Group, as
ATMI may determine, substantially in the form(s) of EXHIBIT F.

     (iii)  Affiliate  Agreement.  Each of the  affiliates of the ADCS Group and
ATMI shall have entered  into an Affiliate  Agreement in the form of EXHIBIT D-1
or EXHIBIT D-2, as appropriate.

     (iv) Escrow Agreement.  Each of the Holders and the escrow agent thereunder
shall  have  entered  into  the  Escrow   Agreement  (the  "Escrow   Agreement")
substantially in the form of EXHIBIT G.

     (v) Indemnification Agreement. Each of the Holders and the ATMI Group shall
have  entered  into  the   Indemnification   Agreement   (the   "Indemnification
Agreement") substantially in the form of EXHIBIT H.

     (vi)  Representations  and  Warranties  of Holders.  Each Holder shall have
executed  and  delivered to the ATMI Group a  Certificate  of Holder in the form
attached hereto as EXHIBIT I making each of the  representations  and warranties
contained therein with respect to such Holder, but only as to that Holder.

     (g) Opinions of Counsel.  (i) Brobeck,  Phleger & Harrison LLP,  counsel to
the  ADCS  Group,  the ADCS  Group  Subsidiaries  and the  Holders,  shall  have
delivered to the ATMI Group an opinion  substantially  in the form of Exhibit J;
and (ii) Lyon & Lyon, patent counsel to the ADCS Group,  shall have delivered to
the ATMI Group an opinion substantially in the form of EXHIBIT K;

     (h) Fairness Opinion.  Alex. Brown & Sons Incorporated,  financial advisers
to ATMI,  shall have  delivered  an opinion to the Board of Directors of ATMI to
the  effect   that  the   Exchange   Consideration   payable   pursuant  to  the
Reorganization is fair from a financial point of view to ATMI.

     (i) Comfort Letter. Ernst & Young LLP, independent  accountants to the ADCS
Group and the ATMI Group, shall have delivered a "comfort" letter,  addressed to
the ADCS Group and the ATMI Group and dated as of the effective  date of the S-4
and the Closing  Date,  in such form and substance as is customary in connection
with such transactions and is satisfactory to the ADCS Group and the ATMI Group.

     (j) Tax Opinion.  Ernst & Young LLP,  independent  accountants  to the ADCS
Group and the ATMI Group,  shall have delivered an opinion letter,  addressed to
the ADCS  Group  and the ATMI  Group and dated as of the  Closing  Date,  to the
effect that the Reorganization has been structured in a manner which is tax-free
with  respect to the ATMI Group and its  stockholders  and the Holders (the "Tax
Opinion").

     (k) Delivery of Certificates  and Assignment.  In exchange for the Exchange
Consideration,  the Holders shall have  delivered (i) each of the original share
certificates  evidencing the Capital Stock,  duly endorsed for transfer with all
requisite transfer stamps, if any are due, attached thereto,  (ii) an assignment
of the Membership Interests,  the form of which is attached hereto as EXHIBIT B,
and (iii) all such other deeds, bills of sale,  assignments and assurances which
Holdings deems reasonably necessary or desirable to vest, perfect or confirm any
and all right,  title or interest in, to or under the  Interests or otherwise to
carry out the purposes of this  Agreement.  Each of the foregoing  shall also be
executed and delivered by each Holder's spouse, if required.

     (l)  Securities  Law  Compliance.  The S-4  registering  the  issuance  and
delivery of the shares of Holdings  Common  Stock  pursuant to the Merger  shall
have been declared effective in accordance with the provisions of the Securities
Act, and no stop order  suspending the  effectiveness of the S-4 shall have been
issued  by the  SEC.  All  other  filings  necessary  under  federal  and  state
securities  laws to permit the  issuance  and delivery of the shares of Holdings
Common  Stock  pursuant  to the  Merger  and of the  Exchange  Consideration  in
compliance  with such laws  shall  have been  made,  and any  authorizations  in
connection therewith from all applicable securities regulatory authorities shall
have been obtained.

     (m) Nasdaq Listing. Holdings Common Stock shall have been, at the Effective
Time, authorized for listing on The Nasdaq National Market.





     (n) Consents and Approvals. The ADCS Group shall have obtained all consents
and approvals and waivers and given such notices as may be reasonably  necessary
to complete properly the restructuring undertaken by the ADCS Group in 1996. The
ADCS Group shall have  obtained all consents and approvals and waivers and given
such notices as may be necessary to  consummate  the  transactions  contemplated
hereby and by the  Additional  Agreements to which it is a party,  including but
not limited to (i) requisite  stockholder,  partner,  member,  etc.  approval or
notification and (ii) the consent to the transactions contemplated hereby of the
parties to all Commitments under which the ADCS Group, any ADCS Group Subsidiary
or any Holder would otherwise be in default

     in any  material  respect  as a  result  of the  transactions  contemplated
hereby,  other than  Commitments  which ATMI agrees are not material to the ADCS
Group or any ADCS  Group  Subsidiary's  business  or  prospects.  All  consents,
authorizations,  orders or approvals of, and filings or registrations  with, any
federal,  state,  local  or  foreign  governmental  commission,  board  or other
regulatory  body which are required  for or in  connection  with the  execution,
delivery and performance of this Agreement and the Additional  Agreements by the
ADCS Group,  any ADCS Group  Subsidiary and the Holders and the  consummation of
the  transactions  contemplated  hereby and  thereby,  and in order to permit or
enable its  business to be  conducted  after the  Closing,  shall have been duly
obtained or made,  except filings under state securities laws, if any, which may
be made in the time period  permitted by law. It is understood that none of such
approvals  shall be deemed to have been received if any such approval is subject
to  satisfaction  of or  compliance  with a  Burdensome  Condition.  "Burdensome
Condition"  shall  mean the  imposition  of a material  restriction  on the ATMI
Group's or the ADCS  Group's  ability  to operate  its  business  following  the
Effective  Time or  requiring  the ATMI  Group or the ADCS Group to dispose of a
material  amount of its assets  following  the Effective  Time.  Either the ATMI
Group or the ADCS  Group  may,  but is not  obligated  to,  seek the  removal or
otherwise satisfactorily resolve the Burdensome Condition.

     (o) No  Material  Adverse  Changes.  There  shall not have been a  material
adverse  change  in  the  general  affairs,  business,  prospects,   properties,
management,  condition  (financial or otherwise) or results of operations of the
ADCS  Group  or  any  ADCS  Group  Subsidiary,   whether  or  not  arising  from
transactions in the ordinary course of business,  and neither the ADCS Group nor
any ADCS Group Subsidiary shall have sustained any material loss or interference
with its business or properties from fire,  explosion,  flood or other casualty,
whether or not covered by  insurance,  or from any labor dispute or any court or
legislative or other governmental action, order or decree.

     (p) Delivery by the ADCS Group. The ADCS Group shall deliver or cause to be
delivered to ATMI:

     (i) With  respect to the ADCS Group,  each ADCS Group  Subsidiary  and each
Holder which is an entity, a complete and correct copy of (i) each corporation's
Certificate or Articles of Incorporation,  as amended to date,  certified by the
Secretary  of  State  of its  state  or  country  of  incorporation,  (ii)  each
corporation's  By-Laws,  as amended to date,  certified  by the  Secretary or an
Assistant Secretary of the respective corporation,  (iii) each limited liability
company's  Articles of Organization or similar  instrument,  as amended to date,
certified  by the  Secretary  of State of its state of  organization,  (iv) each
limited liability company's Operating Agreement or similar agreement, as amended
to date,  certified by a member or manager of the respective  limited  liability
company, (v) each limited partnership's  certificate of limited partnership,  as
amended to date,  certified by the Secretary of State of the State of Texas, and
(vi) ADCS LP's Limited Partnership  Agreement,  as amended to date, certified by
its general partner,  and the original  corporate stock ledgers,  corporate seal
and minute book(s) of the ADCS Group.

     (ii)  Long  form  certificates  of good  standing  or legal  existence,  as
appropriate,  as of a recent  date issued by (i) the  Secretary  of State of the
state in  which  each of the  ADCS  Group  and each  ADCS  Group  Subsidiary  is
organized  to the effect  that each is in good  standing  under the laws of such
state,  and (ii) the  Secretary  of State of each  state in which  that the ADCS
Group or any ADCS Group  Subsidiary  is  authorized  to  transact  business as a
foreign  corporation,  foreign  limited  liability  company or  foreign  limited
partnership  to the effect that the ADCS Group or any ADCS Group  Subsidiary  is
duly qualified as a foreign entity in such state.






     (iii) Certificates issued as of a recent date by the Tax authorities of the
state of  organization  and of each  state in which  the ADCS  Group or any ADCS
Group Subsidiary is authorized to transact business as to the status of the ADCS
Group and each ADCS  Group  Subsidiary's  Tax  liabilities  (including,  but not
limited to, sales tax).

     (iv) Releases  substantially  in the form of EXHIBIT L hereto,  executed by
each Holder.

     (v)  Written  evidence  satisfactory  to ATMI  that all  prior  outstanding
options  to  purchase  any  Securities  of the  ADCS  Group  or any  ADCS  Group
Subsidiary, if any, have been properly terminated.

     (vi)  Such  other  certificates  and   representations  as  are  reasonably
requested by Ernst & Young LLP in order to render the Tax Opinion.

     (vii) Such  further  instruments  or  documents  as the ATMI Group or their
counsel may  reasonably  request to assure the full and effective  completion of
the  Reorganization  and to assure the effective  completion of the transactions
contemplated hereby.

     (q) Termination of Certain Agreements.  The following agreements shall have
been terminated with no further liability thereunder:  (i) that certain Members'
and Shareholders'  Agreement dated January 16, 1996; (ii) that certain Agreement
Regarding  Stock Ownership and  Distribution  dated July 1, 1993; and (iii) that
certain Shareholders' Agreement dated on or about September, 1992.

     (r)  ADCS-Korea.  The  parties  shall  have  obtained  all third  party and
governmental  consents with respect to ADCS-Korea required as a result of, or in
connection  with, the  Reorganization.  The parties shall cooperate in obtaining
and shall use best efforts to obtain such consents.

     6.2. Conditions to the Obligations of the ADCS Group. The obligation of the
ADCS Group to consummate the Exchange and the other transactions contemplated by
this Agreement shall be subject to the satisfaction,  on or prior to the Closing
Date, of each of the following conditions (any of which may be waived in writing
by the ADCS Group in its sole discretion):

     (a) Representations and Warranties True. The representations and warranties
of the ATMI Group  contained in this  Agreement,  or contained in any  Schedule,
certificate  or  other  instrument  or  document  delivered  or to be  delivered
pursuant to this Agreement,  shall be true and correct in all material  respects
on and as of the Closing Date as though such representations and warranties were
made on and as of the Closing Date,  except for the effect of any  activities or
transactions  which  may have  taken  place  after  the  date of this  Agreement
expressly permitted by this Agreement,  incident to carrying out this Agreement,
or consented to in writing by the ADCS Group.  At the Closing,  each of the ATMI
Group shall have delivered to the ADCS Group a certificate (signed on its behalf
by its President and its Chief Financial Officer) confirming the foregoing.

     (b)  Performance.  The ATMI Group shall have  performed and complied in all
material  respects with all of the  obligations  under this Agreement  which are
required to be performed or complied with by it on or prior to the Closing Date.
At the Closing,  each of the ATMI Group shall have delivered to the ADCS Group a
certificate  (signed  on its  behalf by its  President  and its Chief  Financial
Officer) confirming the foregoing.

     (c)  Stockholder  Approval.  This  Agreement  and the  consummation  of the
transaction contemplated herein shall have been duly approved and adopted by the
stockholders  of ATMI in  accordance  with the DGCL and the ATMI  Organizational
Documents.

     (d) Absence of Litigation.  No statute,  rule or regulation shall have been
enacted or promulgated, and no order, decree, writ or injunction shall have been
issued and shall remain in effect,  by any court or  governmental  or regulatory
body,  agency or authority which restrains,  enjoins or otherwise  prohibits the
consummation of the transactions  contemplated  hereby,  and no action,  suit or
proceeding  before  any court or  governmental  or  regulatory  body,  agency or
authority   shall  have  been  commenced   with  respect  to  the   transactions
contemplated





     hereby or with respect to the ATMI Group which, in the reasonable  judgment
of the ADCS  Group,  would have a material  adverse  effect on the  transactions
contemplated hereby or an ATMI Material Adverse Effect.

     (e) Pooling of Interests. The ADCS Group shall have received a letter dated
as of the Effective Time from Ernst & Young LLP, independent  accountants to the
ADCS  Group and the ATMI  Group,  regarding  the  appropriateness  of pooling of
interest  accounting for the  Reorganization  under Accounting  Principles Board
Opinion No. 16.

     (f) Additional Agreements. The ATMI Group shall have executed and delivered
(and shall have agreed to cause  Holdings  to execute  and  deliver  immediately
following  the  Effective  Time, as  applicable)  counterparts  of the following
documents:

    (i) The Certificate of Merger.

    (ii) The Proprietary Information and Inventions Agreements.

    (iii) The Employment Agreements.

    (iv) Affiliate Agreements in the form attached as Exhibit D-2.

    (v) The Registration Rights Agreement.

    (vi) The Escrow Agreement.

    (vii) The Indemnification Agreement.

     (viii) An  employment  agreement  with each of  Eugene  G.  Banucci,  Chief
Executive Officer of ATMI,  Daniel P. Sharkey,  Chief Financial Officer of ATMI,
and Peter S. Kirlin,  Executive  Vice  President of ATMI,  which shall be in the
form of EXHIBIT F and contain the additional terms set forth on SCHEDULE 5.3(P).

     (g)  Opinions of Counsel.  (i) Shipman & Goodwin  LLP,  counsel to the ATMI
Group shall have  delivered  to the ADCS Group an opinion  substantially  in the
form of EXHIBIT M; and (ii) Intellectual Property/Technology Law, patent counsel
to the ATMI  Group,  shall  have  delivered  to the ADCS  Group  (A) an  opinion
substantially in the form of EXHIBIT N and (B) an assessment opinion in the form
of EXHIBIT O with respect to each of the patents listed on SCHEDULE 6.2(G).

     (h) Comfort Letter. Ernst & Young LLP, independent  accountants to the ADCS
Group and the ATMI Group, shall have delivered a "comfort" letter,  addressed to
the ADCS Group and the ATMI Group and dated the Closing  Date,  in such form and
substance  as  is  customary  in  connection  with  such   transactions  and  is
satisfactory to the ADCS Group and the ATMI Group.

     (i) Tax Opinion.  Ernst & Young LLP,  independent  accountants  to the ADCS
Group and the ATMI Group, shall have rendered the Tax Opinion.

     (j)  Securities Law  Compliance.  All filings  necessary  under federal and
state  securities  laws to permit the  issuance  and  delivery  of the  Exchange
Consideration   in  compliance   therewith   shall  have  been  made,   and  any
authorizations in connection therewith from all applicable securities regulatory
authorities shall have been obtained.

     (k) Nasdaq Listing.  Holdings Common Stock, including that constituting the
Exchange  Consideration,  shall have been, at the Effective Time, authorized for
listing on The Nasdaq National Market.

     (l) Consents and Approvals. The ATMI Group shall have obtained all consents
and  approvals  and  waivers  and given  such  notices  as may be  necessary  to
consummate the transactions contemplated hereby and by the Additional Agreements
to which it is a party,  including but not limited to (i) requisite stockholder,
partner,  member,  etc.  approval  or  notification  and (ii) the consent to the
transactions  contemplated  hereby of the parties to all commitments under which
the ATMI Group or any ATMI Group Subsidiary would otherwise be in default





     in any  material  respect  as a  result  of the  transactions  contemplated
hereby,  other than commitments  which the ADCS Group agrees are not material to
the  ATMI  Group or any ATMI  Group  Subsidiary's  business  or  prospects.  All
consents,  authorizations,  orders or approvals of, and filings or registrations
with, any federal,  state, local or foreign  governmental  commission,  board or
other  regulatory  body  which  are  required  for  or in  connection  with  the
execution,  delivery  and  performance  of this  Agreement  and  the  Additional
Agreements by the ADCS Group and any ADCS Group  Subsidiary and the consummation
of the transactions  contemplated hereby and thereby,  and in order to permit or
enable its  business to be  conducted  after the  Closing,  shall have been duly
obtained or made,  except filings under state securities laws, if any, which may
be made in the time period  permitted by law. It is understood that none of such
approvals  shall be deemed to have been received if any such approval is subject
to satisfaction of or compliance  with a Burdensome  Condition.  Either the ATMI
Group or the ADCS  Group  may,  but is not  obligated  to,  seek the  removal or
otherwise satisfactorily resolve the Burdensome Condition.

     (m) No  Material  Adverse  Changes.  There  shall not have been a  material
adverse  change  in  the  general  affairs,  business,  prospects,   properties,
management,  condition  (financial or otherwise) or results of operations (other
than  volatility in the market price of the ATMI Common Stock) of the ATMI Group
whether or not arising from transactions in the ordinary course of business, and
neither the ATMI Group nor any ADCS Group  Subsidiary  shall have  sustained any
material  loss or  interference  with its  business  or  properties  from  fire,
explosion,  flood,  or other casualty,  whether or not covered by insurance,  or
from any labor dispute or any court or legislative or other governmental action,
order or decree.

     (n) Delivery by the ATMI Group. The ATMI Group shall deliver or cause to be
delivered to the ADCS Group:

     (i) With  respect  to the ATMI  Group and each  ATMI  Group  Subsidiary,  a
complete and correct copy of (i) each  corporation's  Certificate or Articles of
Incorporation,  as amended to date,  certified by the  Secretary of State of its
state or country of  incorporation,  and (ii) each  corporation's  By- Laws,  as
amended to date,  certified by the  Secretary  or an Assistant  Secretary of the
respective corporation.

     (ii)  Long  form  certificates  of good  standing  or legal  existence,  as
appropriate,  as of a recent  date issued by (i) the  Secretary  of State of the
state in  which  each of the  ATMI  Group  and each  ADCS  Group  Subsidiary  is
organized  to the effect  that each is in good  standing  under the laws of such
state,  and (ii) the  Secretary  of State of each  state in which  that the ATMI
Group or any ADCS Group  Subsidiary  is  authorized  to  transact  business as a
foreign  corporation,  foreign  limited  liability  company or  foreign  limited
partnership  to the effect that the ADCS Group or any ADCS Group  Subsidiary  is
duly qualified as a foreign entity in such state.

     (iii) Certificates issued as of a recent date by the Tax authorities of the
state of  organization  and of each  state in which  the ATMI  Group or any ADCS
Group Subsidiary is authorized to transact business as to the status of the ATMI
Group and each ADCS  Group  Subsidiary's  Tax  liabilities  (including,  but not
limited to, sales tax).

     (iv)  Such  other  certificates  and   representations  as  are  reasonably
requested by Ernst & Young LLP in order to render the Tax Opinion.

     (v) Such  further  instruments  or  documents  as the  ADCS  Group or their
counsel may  reasonably  request to assure the full and effective  completion of
the  Reorganization  and to assure the effective  completion of the transactions
contemplated hereby.

     (o) Shares of Exchange Consideration. Subject to the deposit into escrow of
shares of Holdings Common Stock contemplated under the Indemnification Agreement
and the Escrow  Agreement,  at the  Closing,  ATMI shall have  delivered  to the
Holders the Exchange  Consideration  issuable to the Holders pursuant to Section
2.3 hereof or irrevocable instruction letters as described in Section 2.1.

     (p)  ADCS-Korea.  Holdings  shall have delivered the  commitments,  if any,
required with respect to the ADCS Korea joint venture upon the change in control
of ADCS Nevada effected at the Closing.





                                   ARTICLE VII

                                     Closing

     7.1.  Closing.  The  closing  of  transactions   contemplated  hereby  (the
"Closing")  shall occur at the offices of Shipman & Goodwin  LLP,  One  American
Row, Hartford,  Connecticut 06103, as soon as reasonably  practicable  following
the meeting of ATMI's  stockholders  described  in Section 5.13 and in any event
within three (3)  business  days after the  satisfaction  or waiver of the other
conditions  set forth in Article VI. The date on which the Closing  occurs shall
be referred to as the "Closing Date".

     7.2.  Simultaneous  Closing.  All actions to be taken on the  Closing  Date
shall be deemed to occur simultaneously and in no event shall be deemed to occur
unless and until all such events have occurred;  provided,  that the election of
Stephen H. Siegele as a director of Holdings  shall not, and shall not be deemed
to, occur prior to the Closing.

                                  ARTICLE VIII

                               Further Assurances

     The parties  agree that they will  execute or furnish  such  documents  and
further  assurances to each other or to proper  authorities  as may be necessary
for  the  full  implementation  and  consummation  of  this  Agreement  and  the
Additional Agreements. This Article VIII shall survive the Closing.

                                   ARTICLE IX

                            Termination of Agreement

     9.1. Termination. This Agreement may be terminated at any time prior to the
Closing,  notwithstanding  the approval of this Agreement by the stockholders of
ATMI:

  (a) by the mutual written consent of ATMI and the ADCS Group;

  (b) by either ATMI or the ADCS Group:

     (i) if any court or  governmental or regulatory  agency,  authority or body
shall have enacted, promulgated or issued any statute, rule, regulation, ruling,
writ or  injunction,  or taken  any  other  action,  restraining,  enjoining  or
otherwise  prohibiting the transactions  contemplated hereby and all appeals and
means of appeal therefrom have been exhausted;

     (ii) if the Closing  shall not have  occurred on or before the later of (A)
August 31, 1997,  subject to extension  pursuant to Section 9.3 hereof,  and (B)
the expiration of any cure period provided herein;  provided,  however, that the
right to terminate this Agreement  pursuant to this Section 9.1(b)(ii) shall not
be  available  to  any  party  whose  (or  whose  affiliate(s)')  breach  of any
representation  or warranty or failure to perform or comply with any  obligation
under this  Agreement  has been the cause of, or resulted in, the failure of the
Closing to occur on or before such date; or

     (iii) for any reason, upon the payment of $5,000,000 to the non-terminating
party  (unless any other  provision of the  Agreement  would permit  termination
without payment of such amount);

     (c) by ATMI (provided it has met its obligations under Section 5.12):

     (i) in the event of a material breach of a representation or warranty as of
the  date  when  made  (or,  in the  case of the  Phase  II  environmental  site
assessment  referred  to in Section  5.23  above,  when  deemed to be made),  or
covenant by the ADCS Group (subject to written notice and a thirty  business day
cure period);





     (ii)  subject to Section 9.3  hereof,  if any Holder  fails,  refuses or is
unable to contribute its Interests in exchange for the Exchange Consideration;

     (iii) if any  condition  to Closing  specified  in Section 6.1 shall not be
satisfied and such condition is not waived by the ATMI Group in its  discretion;
or

     (iv) pursuant to Section 5.23 above; or

     (d) by the ADCS Group  (provided it has met its  obligations  under Section
5.12):

     (i) in the event of a material breach of a representation or warranty as of
the date when made, or covenant by the ATMI Group (subject to written notice and
a thirty business day cure period);

    (ii) pursuant to Section 5.5 above; or

     (iii) if any  condition  to Closing  specified  in Section 6.2 shall not be
satisfied and such condition is not waived by the ADCS Group in its discretion.

     9.2.  Termination  Payment.  No party shall be  entitled  to a  termination
payment unless  otherwise  specified  herein.  In the event that either the ATMI
Group or the ADCS Group shall  terminate this  Agreement  pursuant to subsection
(b)(iii),  the  terminating  party  shall  be  liable  to and  shall  pay to the
non-terminating   party  by  wire   transfer  the  sum  of  $5,000,000  in  full
satisfaction  of  all  claims  within  fifteen  (15)  business  days  after  the
non-terminating  party's receipt of written notice of termination.  In the event
that (i) the ADCS Group shall  terminate this  Agreement  pursuant to subsection
(d)(i) above or (ii) ATMI shall terminate this Agreement  pursuant to subsection
(c)(i) above  (other than with respect to a breach of Section 5.7,  which breach
shall be governed by Section 9.5 below), then the non-terminating party shall be
liable to and shall pay to the  terminating  party by wire  transfer  the sum of
$5,000,000 in full  satisfaction of all claims within fifteen (15) business days
after receipt of written notice of termination by the terminating  party. In the
event that ATMI shall  terminate this Agreement  pursuant to subsection  (c)(ii)
(other  than with  respect to a  failure,  refusal or  inability  to  contribute
described  in Section  9.3),  the ADCS Group shall be liable to and shall pay to
ATMI by wire transfer the sum of $5,000,000 in full  satisfaction  of all claims
within  fifteen (15)  business  days after the ADCS  Group's  receipt of written
notice of  termination by ATMI. It is agreed that the payments due hereunder are
the exclusive remedy for termination of this Agreement.

     9.3.  Failure to Deliver  Interests.  If any  Holder  fails,  refuses or is
unable to contribute its Interests in exchange for the Exchange Consideration as
a direct result of any reason beyond Holder's control and of which Holder had no
knowledge  as of the date of this  Agreement,  including,  but not  limited  to,
Holder's death, disability, bankruptcy, divorce or separation, legal proceeding,
act of any governmental  authority, or act of God, the ATMI Group shall have the
option, after giving notice, to (A) terminate this Agreement,  in which event no
termination  payment as  described  in Section  9.2 will be due,  (B) extend the
Closing Date for a period of up to ninety (90) days,  or (C) close on the Merger
and on the  Exchange  with those  Holders  who have  tendered  their  Interests,
provided  that the Merger and  Exchange  will  qualify as a pooling of interests
transaction.  In the event the Closing  Date is extended  pursuant to clause (B)
above,  the ADCS Group will continue to use its best efforts  during such 90-day
period to cause the Holders to tender their  Interests  at the  Closing.  In the
event the Closing  occurs  pursuant to clause (C) above,  the tendering  Holders
will agree at the Closing to use their best efforts for a period of one (1) year
after the Closing to cause the non- tendering Holders to tender the Interests.

     9.4. Effect of Termination.  In the event of termination of this Agreement,
this Agreement  shall  forthwith  become void and there shall be no liability on
the part of any of the parties hereto or their respective affiliates, directors,
officers, stockholders,  general partners, limited partners, and members, except
for Section 5.6,  Section 9.2 and the last sentence of Section 5.1,  which shall
remain in full force and effect.

     9.5.  Breach of Section  5.7. In the event of a breach by the ADCS Group or
any ADCS Group Subsidiary of Section 5.7 (subject to written notice and a thirty
business  day cure  period),  the ATMI  Group may  pursue  any and all  remedies
available to it at law or in equity. Recovery by the ATMI Group of a termination
payment  under  Section  9.2 shall not bar any such action for breach of Section
5.7,  but the amount of any monetary  damages  awarded to the ATMI Group in such
action shall be reduced by the termination payment actually received by the ATMI
Group.





                                    ARTICLE X

                                  Miscellaneous

     10.1.  Right of Set-Off.  Any party to this Agreement  shall be entitled to
set-off  against  any  amounts  due to  another  party  under  the terms of this
Agreement  or under any  Additional  Agreement,  any amounts due from such other
party under the terms of this Agreement.

     10.2.  Benefits  of this  Agreement.  Nothing  in this  Agreement  shall be
construed to give any benefits to any person  (including,  without  limiting the
generality of the foregoing, any present or former employee of the ADCS Group or
any ADCS Group  Subsidiary) or corporation or other entity,  other than the ADCS
Group, the Holders, ATMI, Holdings, Newco and the Surviving Corporation,  except
for persons  entitled to the  protections  afforded  by Section  5.21;  and this
Agreement  shall be for the sole and  exclusive  benefit of the ADCS Group,  the
Holders,  and  the  ATMI  Group.  The  obligations  of the  ADCS  Group  and the
obligations of the ATMI Group shall be joint and several.

     10.3.  Successors  and Assigns.  This  Agreement may not be assigned by any
party  without  the prior  written  consent of all of the parties  hereto.  This
Agreement  shall bind and inure to the benefit of the  parties  hereto and their
respective heirs, administrators, executors, successors and permitted assigns.

     10.4. Notices.  All notices,  consents,  waivers,  and other communications
under this  Agreement  must be in  writing  and will be deemed to have been duly
given when (a) delivered by hand (with  written  confirmation  of receipt),  (b)
sent by facsimile (if sent during regular business hours,  otherwise on the next
business day) (with written  confirmation  of receipt),  provided that a copy is
mailed by registered mail, return receipt requested, or (c) when received by the
addressee,  if  sent by  certified  mail or a  nationally  recognized  overnight
delivery service (receipt requested),  in each case to the appropriate addresses
and facsimile  numbers set forth below (or to such other addresses and facsimile
numbers as a party may designate by notice to the other parties):

    If to the ATMI Group:

    Advanced Technology Materials, Inc.
    7 Commerce Drive
    Danbury, CT 06810-4169
    Facsimile No. (203) 792-8040
    Attention Eugene Banucci

    with copies to:

    Frank J. Marco, Esq.
    Shipman & Goodwin LLP
    One American Row
    Hartford, CT 06103-2819
    Facsimile No. (860) 251-5900

    If to the ADCS Group:

    Advanced Delivery & Chemical Systems Nevada, Inc.
    6805 Capital of Texas Highway, Suite 330
    Austin, TX 78731
    Facsimile No. (512) 418-1909
    Attention Stephen H. Siegele




    with copies to:

    Carmelo M. Gordian, Esq.
    Brobeck, Phleger & Harrison LLP
    301 Congress Avenue
    Suite 1200
    Austin, TX 78701
    Facsimile No. (512) 477-5813

     By its  inclusion  herein as a recipient of copies of notices,  the parties
acknowledge  and agree that  notwithstanding  the fact that  Brobeck,  Phleger &
Harrison LLP represented the ADCS Group (which effective as of the Closing shall
be wholly owned by Holdings) in connection with the transactions contemplated by
the Exchange Agreement,  Brobeck,  Phleger & Harrison LLP shall be permitted (A)
to represent the Holders and their respective heirs, executors,  administrators,
affiliates,  successors and assigns in connection with any and all matters which
may arise out of or in connection with this Agreement,  the Escrow  Agreement or
any of the other Additional Agreements; and (B) that upon receipt of appropriate
conflict waiver letters,  if any be required,  and subject to applicable ethical
obligations  of  attorneys,  shall be  entitled  to  represent  any of the other
parties to this Agreement,  the Escrow Agreement or the Additional Agreements on
any other matters which any such party may request; provided,  however, that the
foregoing consent and waiver are applicable only to any conflict which may arise
out of the matters referred to above.

     10.5. Severability. In the event any covenant, condition or other provision
of this Agreement is held to be invalid or  unenforceable by a final judgment of
a court of  competent  jurisdiction,  then  such  covenant,  condition  or other
provision shall be automatically  terminated and performance thereof waived, and
such  invalidity  or  unenforceability  shall in no way  affect any of the other
covenants,  conditions  or  provisions  hereof,  and the  parties  hereto  shall
negotiate  in  good  faith  to  agree  to  such  amendments,   modifications  or
supplements of or to this Agreement or such other appropriate actions as, to the
maximum extent practicable, shall implement and give effect to the intentions of
the parties as reflected herein.

     10.6 Pooling.  If any provision of this Agreement or the application of any
such provisions to any person or  circumstance  precludes the use of "pooling of
interests"  accounting  treatment in connection  with the  Reorganization,  then
provided the parties  mutually agree (A) such provision shall be of no force and
effect to the  extent  and  solely to the  extent  necessary  to  preserve  such
accounting   treatment   for  the   Reorganization;   (B)  such   invalidity  or
unenforceability  shall in no way affect any of the other provisions hereof; and
(C)  the  parties  hereto  shall  negotiate  in  good  faith  to  agree  to such
amendments,  modifications  or supplements of or to this Agreement or such other
appropriate  actions  in  order,  to the  maximum  extent  practicable,  for the
Reorganization  to  be  treated  as a  "pooling  of  interests"  for  accounting
purposes.

     10.7.  Entire  Agreement;  Amendment.  This Agreement,  the Schedules,  the
Exhibits,  the Additional  Agreements and the  Confidentiality  Agreement  dated
October 22, 1996  between  ADCS LP and ATMI contain all of the terms agreed upon
by the parties  with  respect to the  subject  matter  hereof,  and there are no
representations or understandings between the parties except as provided herein.
Without  limiting the generality of the foregoing,  this Agreement  specifically
supersedes  the letter of intent  dated  January 10, 1997  between ATMI and ADCS
Nevada,  ADCS Manager and ADCS  Holdings.  This  Agreement may not be amended or
modified  in any way  except  by a  written  amendment  to this  Agreement  duly
executed by ATMI and ADCS Nevada.

     10.8.  Waiver. No waiver of a breach of, or default under, any provision of
this  Agreement  shall be deemed a waiver of such provision or of any subsequent
breach or  default of the same or similar  nature or of any other  provision  or
condition of this Agreement.

     10.9.  Applicable  Law. This  Agreement  shall be governed by and construed
(both as to validity and  performance)  and enforced in accordance with the laws
of the State of  Delaware  applicable  to  agreements  made and to be  performed
wholly within such jurisdiction.





     10.10.  Jurisdiction.  Each party hereby  irrevocably:  (1) agrees that any
suit,  action, or other legal proceeding arising out of this Agreement or out of
any of the transactions  contemplated  hereby or thereby,  may be brought in any
New York state court or United  States  federal  court  located in the  southern
district of New York; (2) consents to the jurisdiction of each such court in any
such suit,  action,  or legal  proceeding;  (3) waives any objection  which such
party  may  have to the  laying  of venue of any  such  suit,  action,  or legal
proceeding in any of such courts; and (4) agrees that New York state is the most
convenient forum for litigation of any such suit, action, or legal proceeding.

     10.11.  Counterparts.  This  Agreement  may be  executed  in any  number of
counterparts  with the same effect as if the signatures  thereto and hereto were
upon the same instrument,  but all of such counterparts  taken together shall be
deemed to constitute one and the same instrument.

     10.12  Knowledge.  As  used  herein,  "knowledge"  means  knowledge  of the
executive  management  of the ADCS Group or the ATMI Group,  as the case may be,
after  making  reasonable  inquiry  of  the  knowledge  of  officers  or  senior
management employees having  responsibility for those operations or transactions
to which such  representation and warranty relates. An individual will be deemed
to have "knowledge" of a particular fact or other matter if:

    (i) such individual is actually aware of such fact or other matter; or

     (ii) a  reasonably  prudent  individual  could be  expected  to discover or
otherwise  become  aware of such fact or other  matter  in the  course of making
reasonable  inquiry of the  knowledge  of other  officers  or  employees  having
general  responsibility  for those  operations  or  transactions  to which  such
representation and warranty relates.

                                     EXHIBIT


     The  following  schedules and exhibits have been omitted from the Agreement
and Plan of Merger and  Exchange  attached  to this  registration  statement  as
Appendix  A  to  the  Proxy  Statement/Prospectus  and  incorporated  herein  by
reference:

                                    SCHEDULES

Schedule A                     Holders
Schedule 1.4                   Directors of Surviving Corporation
Schedule 1.5                   Officers of Surviving Corporation
Schedule 2.3(a)                Exchange Consideration
ADCS Disclosure Schedule
ATMI Disclosure Schedule
Schedule 5.2                   Permitted Pre-Closing Activities of ADCS
Schedule 5.3(p)                Permitted Employment Agreements by ATMI
Schedule 5.8                   Post-Closing Operations
Schedule 6.2(g)                ATMI Assessment Opinion Patents


                                    EXHIBITS

Exhibit A               Form of Certificate of Merger
Exhibit B               Form of Assignment of Membership Interests
Exhibit C               Form of Registration Rights Agreement
Exhibit D-1             Form of Affiliates Agreement of ADCS
Exhibit D-2             Form of Affiliates Agreement of ATMI
Exhibit E               Form of Proprietary Information and Inventions Agreement
Exhibit F               Form of Employment Agreements
Exhibit G               Form of Escrow Agreement
Exhibit H               Form of Indemnification Agreement
Exhibit I               Form of Certificate of Holder
Exhibit J               Form of Opinion of Counsel to ADCS
Exhibit K               Form of Opinion of Patent Counsel to ADCS
Exhibit L               Form of Releases
Exhibit M               Form of Opinion of Counsel to ATMI
Exhibit N               Form of Opinion of Patent Counsel to ATMI (General)
Exhibit O               Form of Assessment Opinion of Patent Counsel to ATMI


     The  Registrant  agrees to  furnish  supplementally  a copy of any  omitted
schedule or exhibit to the Securities and Exchange Commission upon request.

                            [SIGNATURE PAGES FOLLOW.]





  IN WITNESS WHEREOF,  the parties hereto have caused this Agreement and Plan of
Merger and Exchange to be executed as of the date first written above.

Advanced Technology Materials, Inc.


By: /s/ Eugene G. Banucci
- ---------------------------------
Eugene G. Banucci
Chief Executive Officer

ATMI Holdings, Inc.


By: /s/ Eugene G. Banucci
- ---------------------------------
Eugene G. Banucci
President

Alamo Merger, Inc.


By: /s/ Daniel P. Sharkey
- ---------------------------------
Daniel P. Sharkey
President

Advanced Delivery & Chemical Systems
Nevada, Inc.


By: /s/ Stephen H. Siegele
- ---------------------------------
Stephen H. Siegele
President

Advanced Delivery & Chemical Systems
Manager, Inc.


By: /s/ Stephen H. Siegele
- ---------------------------------
Stephen H. Siegele
President





Advanced Delivery & Chemical Systems
Holdings, LLC

By: Advanced Delivery & Chemical
Systems Nevada, Inc., Its
Manager


By: /s/ Stephen H. Siegele
- ---------------------------------
Stephen H. Siegele
President

Advanced Delivery & Chemical Systems
Operating, LLC

By: Advanced Delivery &
ChemicalSystems Manager, Inc.,
Its Manager


By: /s/ Stephen H. Siegele
- ---------------------------------
Stephen H. Siegele
President

Advanced Delivery & Chemical
Systems, Ltd.

By: Advanced Delivery & Chemical
Systems Operating, LLC, Its
General Partner

By: Advanced Delivery & Chemical
Systems Manager, Inc., Its
Manager


By: /s/ Stephen H. Siegele
- ---------------------------------
Stephen H. Siegele
President