EXHIBIT 10(a)








                       ASSET AND SHARE PURCHASE AGREEMENT





                                  by and among 




                         Thermo Instrument Systems Inc.,

                             ATI Acquisition Corp.,

                          Analytical Technology, Inc., 

                       and, for certain limited purpuses,

                                 Thermedics Inc.





                          Executed on November 29, 1995
PAGE








                       ASSET AND SHARE PURCHASE AGREEMENT


             THIS AGREEMENT, dated as of the 29th day of November, 1995,
        by and among Thermo Instrument Systems Inc., a Delaware
        corporation having an office at 504 Airport Road, Santa Fe, New
        Mexico  87504 ("Thermo Instrument"), ATI Acquisition Corp., a
        Wisconsin corporation and a wholly-owned subsidiary of Thermo
        Instrument ("Acquisition"), and Analytical Technology, Inc., a
        Delaware corporation having an office at The Schrafft Center, 529
        Main Street, Boston, Massachusetts  02129 ("ATI").  Thermedics
        Inc. ("Thermedics") is made a party to this Agreement for
        purposes of Section 1.3 hereof. 

             For and in consideration of the mutual covenants and
        agreements hereinafter set forth, and other good and valuable
        consideration, the receipt and sufficiency of which is
        acknowledged by each party hereto, the parties hereto agree as
        follows:


                                    ARTICLE 1

                                 THE TRANSACTION

             Section 1.1.  Sale and Purchase of Assets and Shares.

                  (a)  Assets and Shares to be Purchased.  At the Closing
        (as defined in Section 2.1 hereof), ATI will sell, convey,
        transfer, assign and deliver or cause to be sold, conveyed,
        transferred, assigned and delivered to Acquisition, and
        Acquisition will purchase from ATI, for the purchase price
        specified in Section 1.2 and subject to the terms and conditions
        hereof, the "Assets," as hereinafter defined.  The term "Assets"
        shall mean all of ATI's right, title and interest in and to all
        property, whether real or personal, whether tangible or
        intangible, wheresoever situated and whether or not specifically
        referred to herein or in any instrument or conveyance delivered
        pursuant hereto, primarily employed in or primarily related to
        its analytical instrument business, including without limitation
        the business carried on by its Mattson Instruments, Unicam
        Analytical Systems and Cryolect Scientific divisions and the
        TGA/DCA and Capillary Electrophoresis product lines of its Cahn
        division (the "Business"), and including without limitation, the
        personal property described below in this Section 1.1(a):

                       (i)  Real Property.  All of ATI's rights under
        leases relating to the real property located at (i) 1004 Fourier
        Drive, Madison, Wisconsin and (ii) 2109-2113 Eagle Drive,
        Middleton, Wisconsin;
PAGE






                       (ii)  Inventories.  All inventories of raw
        materials, work in process, finished products and resale
        merchandise, scrap inventory, expendable manufacturing supplies
        and similar items owned by ATI and related to the Business;

                       (iii)  Machinery and Equipment.  All machinery and
        equipment, wherever located, that are owned by ATI and that are
        primarily employed in, or primarily relate to, the manufacture,
        production, assembly, handling, distribution and sale of products
        for the Business, together with the spare parts inventories and
        all manufacturing or production tools and maintenance supplies
        pertaining thereto;

                       (iv)  Furniture and Fixtures.  All office
        furniture, office equipment and office supplies and computer
        hardware owned by ATI that are primarily employed in, or
        primarily related to, the Business (except for such items located
        at ATI's corporate headquarters); 

                       (v)  Personal Property Leases.  All right, title
        and interest of ATI under leases for personal property included
        in the Assumed Liabilities (as defined in Section 1.4 hereof);

                       (vi)  Patents and Trademarks.  All right, title
        and interest of ATI in, under or to all patents, trademarks,
        service marks, copyrights, trade names, logos, and applications
        therefor related primarily to the Business, including (i) any
        logo and any corporate and/or trade name including the words
        "Mattson," "Unicam" and/or "Cryolect" and (ii) the patents,
        trademarks, service marks, copyrights, trade names, logos, and
        applications therefor listed or described on Schedule 1.1(a)(vi)
        hereto;

                       (vii)  Technical Information.  All inventions,
        discoveries (whether patentable or unpatentable), processes,
        designs, know-how, trade secrets, proprietary data, technology
        and other intellectual property of all kinds owned by or licensed
        to ATI and that are primarily employed in, or primarily related
        to, the Business, including all drawings, plans, specifications,
        processes, patterns, dies, designs, blueprints, records, data,
        product development records, production outlines, information, or
        knowledge and procedures relating to any of such intellectual
        property; 

                       (viii)  Contract Rights and Miscellaneous
        Intangibles.  All right, title and interest of ATI in, under and
        to all sales, distribution and purchase agreements, and the other
        agreements, contracts, sales orders, backlog, and commitments of
        ATI related to the Business and in, under and to all equipment
        lists, parts lists, computer tapes and discs, systems and
        programs, proprietary software that pertain to the Assets and the
        operation and use thereof in the Business;



                                        2
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                       (ix)  Cash and Cash Equivalents.  All right, title
        and interest of ATI in cash, cash in banks, cash equivalents,
        deposits, investments, funds, certificates of deposit, drafts,
        checks and similar instruments that are outstanding and in
        existence on the Closing Date (as defined in Section 2.1 hereof)
        and that are related to the Business;

                       (x)  Accounts Receivable.  All accounts and notes
        receivable of ATI existing on the Closing Date and related to
        products sold or services performed by the Business, as well as
        ATI's right to payment for products sold or services performed by
        the Business but not yet billed as of the Closing, and all
        accounts and notes receivable of ATI existing on the Closing Date
        due from or payable by any of the Acquired Companies (as defined
        in Section 1.1(a)(xii) below);

                       (xi)  Motor Vehicles.  All cars, trucks and other
        motor vehicles listed or described on Schedule 1.1(a)(xi) hereto;

                       (xii)  Shares of Certain Subsidiaries.  All of the
        issued and outstanding shares of capital stock of each of the
        following companies:  (A) Mattson Instruments, Limited (a company
        organized under the laws of the United Kingdom); (B) Unicam
        Technology Limited (a company organized under the laws of the
        United Kingdom); (C) Unicam S.A. (a company organized under the
        laws of Belgium); Unicam Analytical Inc. (a company organized
        under the laws of Ontario); (D) Unicam France S.A. (a company
        organized under the laws of France); (E) Unicam Italia SpA (a
        company organized under the laws of Italy); (F) Unicam Analytical
        Technology Netherlands B.V. (a company organized under the laws
        of the Netherlands); and (G) Unicam Analytische System GmbH (a
        company organized under the laws of Germany) (all such shares of
        capital stock, collectively, the "Shares"); (each of such
        companies, and each entity of which fifty percent (50%) or more
        of the effective voting power or equity interest is owned
        directly or indirectly by any of such companies, including
        without limitation: (I) Unicam Limited (a company organized under
        the laws of the United Kingdom) and (II) Unicam Export Limited (a
        company organized under the laws of the United Kingdom), each an
        "Acquired Company" and, collectively, the "Acquired Companies");

                       (xiii)  Books and Records.  All general books of
        account, books of original entry and other records of ATI,
        wherever located, that relate primarily to the Business,
        including without limitation customer and supplier lists, and all
        general books of account and books of original entry that
        comprise the permanent accounting or tax records and books and
        records (including corporate minutes and stock transfer records)
        of each Acquired Company that such Acquired Company is required
        to retain pursuant to any statute, rule or regulation; 

                       (xiv)  Licenses.  All existing permits, licenses,
        regulatory approvals and franchises of or from any national,
        regional, state or local government or authority relating

                                        3
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        primarily to the Business (to the extent transfer is permitted by
        law);  

                       (xv)  Tax Refunds.  All of ATI's right, title and
        interest in and to government refunds of federal, state, local,
        foreign and provincial income, capital gains, property transfer,
        payroll, withholding, excise, sales, use, use and occupancy,
        mercantile, real estate, personal property, value added, capital
        stock, franchise or other taxes and estimated taxes relating
        thereto (and interest and penalties thereon) with respect to the
        Business; and

                       (xvi)  Miscellaneous Supplies.  All catalogs,
        brochures, product literature, printed materials, shipping and
        packaging materials and labels, cartons and shipping containers,
        pallets, shipping equipment, graphics, art work, photographic
        film, slides, negatives, color separations, printer's and
        photographer's plates and so-called "camera ready materials" and
        sales and advertising materials owned by ATI and that are either
        physically located at any of the Property or that are primarily
        employed in, or primarily related to, the Business.

                  (b)  Retained Assets.  Notwithstanding anything
        contained in Section 1.1(a) to the contrary, ATI shall retain,
        and the Assets shall not include, any property, whether real or
        personal, whether tangible or intangible, wheresoever situated
        and whether or not specifically referred to herein, owned by ATI
        and primarily employed in or primarily related to its laboratory
        products business, including without limitation the business
        carried on by its Orion Research, Cahn Instruments and/or Russell
        pH divisions (collectively, the "Laboratory Products Division"),
        and including without limitation, the personal property described
        below in this Section 1.1(b) (collectively, the "Retained
        Assets"):

                       (i)  Real Property.  ATI's rights under leases
        relating to the real property located at (i) The Schrafft Center,
        529 Main Street, Boston, Massachusetts; and (ii) Industrialville
        Industrial Park, State Highway Number 190, Km 1.5, in Carolina,
        Puerto Rico;

                       (ii)  Inventories.  Any inventories of raw
        materials, work in process, finished products and resale
        merchandise, scrap inventory, expendable manufacturing supplies
        and similar items owned by ATI and related to the Laboratory
        Products Division;

                       (iii)  Machinery and Equipment.  Any machinery and
        equipment, wherever located, that are owned by ATI and that are
        primarily employed in, or primarily relate to, the manufacture,
        production, assembly, handling, distribution and sale of products
        for the Laboratory Products Division, together with the spare
        parts inventories and any manufacturing or production tools or
        maintenance supplies pertaining thereto;

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PAGE







                       (iv)  Furniture and Fixtures.  Any office
        furniture, office equipment or office supplies or computer
        hardware owned by ATI that are primarily employed in, or
        primarily related to, the Laboratory Products Division, including
        without limitation all such items located at ATI's corporate
        headquarters; 

                       (v)  Personal Property Leases.  Any right, title
        or interest of ATI under leases for personal property not
        specifically included in the Assumed Liabilities;

                       (vi)  Patents and Trademarks.  Any right, title or
        interest of ATI in, under or to any patents, trademarks, service
        marks, copyrights, trade names, logos, and applications therefor
        related primarily to the Laboratory Products Division, including
        (i) any logo and any corporate and/or trade name including the
        words "Orion, "Cahn" and/or "Russell pH";

                       (vii)  Technical Information.  Any inventions,
        discoveries (whether patentable or unpatentable), processes,
        designs, know-how, trade secrets, proprietary data, technology or
        other intellectual property of any kind owned by or licensed to
        ATI that are primarily employed in, or primarily related to, the
        Laboratory Products Division, including any drawings, plans,
        specifications, processes, patterns, dies, designs, blueprints,
        records, data, product development records, production outlines,
        information, or knowledge and procedures relating to any of such
        intellectual property; 

                       (viii)  Contract Rights and Miscellaneous
        Intangibles.  Any right, title or interest of ATI in, under or to
        any sales, distribution and purchase agreements, and the other
        agreements, contracts, sales orders, backlog, and commitments of
        ATI related to the Laboratory Products Division or in, under or
        to any equipment lists, parts lists, computer tapes and discs,
        systems and programs, proprietary software that pertain to the
        Retained Assets and the operation and use thereof by the
        Laboratory Products Division;

                       (ix)  Cash and Cash Equivalents.  Any right, title
        or interest of ATI in cash, cash in banks, cash equivalents,
        deposits, investments, funds, certificates of deposit, drafts,
        checks and similar instruments that are outstanding and in
        existence on the Closing Date and that are related to the
        Laboratory Products Division;

                       (x)  Accounts Receivable.  Any accounts or notes
        receivable of ATI existing on the Closing Date and related to
        products sold or services performed by the Laboratory Products
        Division, or ATI's right to payment for products sold or services
        performed by the Laboratory Products Division but not yet billed
        as of the Closing;


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                       (xi)  Motor Vehicles.  Any cars, trucks or other
        motor vehicles listed or described on Schedule 1.1(b)(xi) hereof;

                       (xii)  Shares of Capital Stock.  The capital stock
        of any corporation or company other than the companies identified
        in Section 1.1(a)(xii);

                       (xiii)  Books and Records.  Any general books of
        account, books of original entry or other records of ATI,
        wherever located, that relate primarily to the Laboratory
        Products Division; 

                       (xiv)  Licenses.  Any existing permits, licenses,
        regulatory approvals or franchises of or from any national,
        regional, state or local government or authority relating
        primarily to the Laboratory Products Division;  

                       (xv)  Tax Refunds.  Any of ATI's right, title or
        interest in or to government refunds of federal, state, local,
        foreign and provincial income, capital gains, property transfer,
        payroll, withholding, excise, sales, use, use or occupancy,
        mercantile, real estate, personal property, value added, capital
        stock, franchise or other taxes and estimated taxes relating
        thereto (and interest and penalties thereon) with respect to the
        Laboratory Products Division; or

                       (xvi)  Miscellaneous Supplies.  Any catalogs,
        brochures, product literature, printed materials, shipping and
        packaging materials or labels, cartons or shipping containers,
        pallets, shipping equipment, graphics, art work, photographic
        film, slides, negatives, color separations, printer's and
        photographer's plates or so-called "camera ready materials" or
        sales or advertising materials owned by ATI and that are
        primarily employed in, or primarily related to, the Laboratory
        Products Division.

             Section 1.2.  Purchase Price. The aggregate purchase price
        to be paid to ATI by Acquisition for the Assets shall be
        $34,932,830 (as reduced pursuant to following sentence and as
        adjusted pursuant to the terms of Section 1.3, the "Purchase
        Price"), plus the assumption of certain liabilities of ATI as
        hereinafter provided.  At the Closing, Acquisition shall deliver
        to ATI Acquisition's promissory note, in the form set forth as
        Exhibit A to this Agreement (the "Note"), representing the
        obligation of Acquisition to pay the Purchase Price to ATI in
        cash immediately after the consummation of the transactions
        contemplated by the TMD Agreement.

             Section 1.3.  Adjustments to Purchase Price.

                  (a)  Thermo Instrument and Acquisition acknowledge
        that, pursuant to Section 1.3 of the TMD Agreement, Thermedics
        shall cause ATI to prepare a consolidated balance sheet of ATI
        and its subsidiaries, as of the end of ATI's fiscal month next

                                        6
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        preceding the Closing Date, but without giving effect to the
        transactions contemplated by this Agreement (the "Closing Balance
        Sheet"), which Closing Balance Sheet shall be the basis for an
        adjustment of the aggregate amount paid by Thermedics pursuant to
        the TMD Agreement (the "TMD Purchase Price").  Thermedics, Thermo
        Instrument and Acquisition agree that, in the event that the TMD
        Purchase Price is actually adjusted pursuant to Section 1.3 of
        the TMD Agreement, then the Purchase Price payable hereunder by
        Acquisition shall then be either increased or decreased, as may
        be appropriate, to the extent that such adjustment to the TMD
        Purchase Price is attributable to the operations of the Business.

                  (b)  In the event that the parties to the TMD Agreement
        find it necessary or desirable to retain an accounting firm to
        resolve any dispute between them with respect to the Closing
        Balance Sheet pursuant to Section 1.3(d) of the TMD Agreement,
        then Acquisition shall reimburse Thermedics for one-half of the
        portion of the fees and expenses of such accounting firm that are
        actually paid by Thermedics.

                  (c)  If Thermedics and Thermo Instrument are unable to
        agree on the portion of any adjustment to the TMD Purchase Price
        that is attributable to the operations of the Business, then they
        shall retain a nationally recognized accounting firm to resolve
        any dispute between them and the determination of such accounting
        firm shall be binding upon them and their respective
        subsidiaries.  In such event, Thermedics and Thermo Instrument
        shall each pay one-half of such accounting firm's fees and
        expenses.

             Section 1.4.  Assumption of Liabilities.  Subject to the
        terms and conditions contained in this Agreement, Acquisition
        shall, at the Closing, assume and agree to pay or perform, or
        cause to be paid or performed, only (a) those obligations and
        liabilities of ATI that (i) are accurately reflected on the
        unaudited consolidated balance sheet of ATI as at September 30,
        1995 (the "Pre-Closing Balance Sheet") and (ii) relate solely or
        primarily to the Business (including without limitation all such
        obligations and liabilities of ATI to any of the Acquired
        Companies); and (b) those liabilities, duties and obligations
        under contracts or agreements that comprise a portion of the
        Assets (together, the "Assumed Liabilities").  Acquisition will
        not assume any liabilities of the ATI other than Assumed
        Liabilities.

             Section 1.5.  Escrow Account.  Thermo Instrument and
        Acquisition acknowledge that pursuant to Section 1.5 of the TMD
        Agreement, for the purpose of providing support of the
        representations and warranties of ATI contained herein and to
        induce Thermo Instrument and Acquisition to enter into this
        Agreement, $5,000,000 shall be withheld from the payment of the
        TMD Purchase Price at the Closing and shall be set aside in
        escrow (the "Escrow Account") pursuant to the terms of an
        Indemnification and Escrow Agreement to be entered into at the

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        Closing by and among Thermedics, Thermo Instrument, ATI, the
        Shareholder Representative (as defined in the TMD Agreement) and
        BayBank N.A., as escrow agent, in substantially the form of
        Exhibit B hereto (the "Escrow Agreement").  The funds placed in
        escrow pursuant to Section 1.5 of the TMD Agreement, together
        with any interest or earnings thereon, shall be considered the
        "Escrowed Funds."  The Escrowed Funds shall be held as a trust
        fund and shall not be subject to any lien, attachment, trustee
        process or any other judicial process of any creditor of any
        party, and shall be held and disbursed by the Escrow Agent solely
        for the purposes and in accordance with the terms of the Escrow
        Agreement.  

             Section 1.6.  Adoption by Shareholders.  This Agreement
        shall be promptly submitted for approval to ATI's shareholders
        (the "Shareholders") either at a duly called and held shareholder
        meeting (the "Shareholder Meeting") or by majority written
        consent pursuant to the General Corporation Law of the State of
        Delaware (the "General Corporation Law").  The Board of Directors
        of ATI shall recommend to the Shareholders the approval of this
        Agreement and the transactions contemplated hereby.

             Section 1.7.  Allocation of Purchase Price.  The Purchase
        Price shall be allocated among the Assets and the Shares as set
        forth in Exhibit C hereto.  ATI and Acquisition each will report
        the federal, state, provincial, foreign and local income and
        other tax consequences of the purchase and sale contemplated
        hereby in a manner consistent with such allocation and will not
        take any position inconsistent therewith upon examination of any
        tax return, in any refund claim, in any litigation, or otherwise.


                                    ARTICLE 2

                                     CLOSING

             Section 2.1.  Time and Place of Closing.  The closing under
        this Agreement (herein called the "Closing") shall take place at
        the offices of Thermo Electron Corporation, 81 Wyman Street,
        Waltham, Massachusetts  02254 at 10:00 a.m., local time, on the
        day of the later of (i) the approval by the Shareholders of the
        execution, delivery and performance by ATI of this Agreement and
        (ii) the satisfaction of all other conditions to Closing as set
        forth in Article 5 hereof, or at such other time or date as may
        be mutually agreeable to the parties hereto (the date on which
        the Closing occurs being herein called the "Closing Date").  All
        transactions at the Closing shall be deemed to take place
        simultaneously and no transaction shall be deemed to have been
        completed and no document or certificate shall be deemed to have
        been delivered until all transactions are completed and all
        documents delivered.




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             Section 2.2.  Deliveries and Proceedings at Closing.

                  (a)  Deliveries by ATI.  ATI will deliver to
        Acquisition such deeds, bills of sale and share transfer
        documentation and other instruments of conveyance, transfer and
        assignment, dated the Closing Date and in form and substance
        reasonably satisfactory to Acquisition's counsel, as shall in the
        judgment of such counsel be sufficient to vest in Acquisition all
        of the right, title and interest in and to the Assets (including
        the Shares).  

                  (b)  Deliveries by Acquisition.  Acquisition will
        deliver to ATI the Note and such instruments of assumption of
        liabilities, dated the Closing Date and in form and substance
        reasonably satisfactory to ATI's counsel, as shall in the
        judgment of such counsel be sufficient to vest in Acquisition the
        obligations to satisfy and discharge the Assumed Liabilities.

             Section 2.3.  Additional Action to Assure Transferees.
        Nothing in this Agreement shall be construed to assign any
        contract, right, commitment, agreement, permit, franchise, or
        claim included in the Assets (individually, a "Purchased Contract
        Right") which is by its terms or by law nonassignable without the
        consent of the other party or parties thereto, unless such
        consent shall have been given, or as to which all the remedies
        for the enforcement thereof enjoyed by ATI would not, as a matter
        of law, pass to Acquisition as an incident of the assignments
        provided for by this Agreement.  In order, however, to provide
        Acquisition the full realization and value of every Purchased
        Contract Right of the character hereinbefore described, ATI at
        and after the Closing will, at the request and under the
        direction of Acquisition and in the name of ATI or otherwise as
        Acquisition shall specify, take or cause to be taken all such
        action (including without limitation the appointment of
        Acquisition as attorney-in-fact for ATI, but with powers limited
        to the specific purposes contemplated hereby) and do or cause to
        be done all such things as shall in the reasonable opinion of
        Acquisition be necessary or proper to (a) assure that the rights
        of ATI under all Purchased Contract Rights shall be preserved for
        the benefit of Acquisition, and (b) facilitate receipt by
        Acquisition of the consideration to which ATI would otherwise be
        entitled in and under all Purchased Contract Rights, which
        consideration shall be held for the benefit of, and shall be
        delivered to, Acquisition.  In order to accomplish the foregoing,
        ATI may designate Acquisition as a subcontractor to perform
        obligations of ATI under any Purchased Contract Rights.  


                                    ARTICLE 3

                             [Intentionally Omitted]




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                                    ARTICLE 4

                                    COVENANTS

             Section 4.1.  Satisfaction of Conditions Precedent.  The
        parties hereby agree, subject to the terms and conditions
        provided in this Agreement, to use their reasonable efforts to
        take, or cause to be taken, all action, and to do, or cause to be
        done, all things necessary, appropriate or desirable under
        applicable laws and regulations to consummate the transactions
        contemplated by this Agreement, including the satisfaction of the
        conditions precedent contained in Article 5 hereof.  Each party
        will use their respective reasonable efforts to obtain consents
        of all third-parties and governmental authorities necessary,
        appropriate or desirable for the consummation of the transactions
        contemplated by this Agreement.  

             Section 4.2.  Shareholders' Approval.  ATI shall take all
        action necessary in accordance with applicable law to submit this
        Agreement to the Shareholders for approval and adoption at the
        earliest possible time.  Subject only to the exercise of its
        fiduciary duty upon advice of counsel, ATI's Board of Directors
        shall recommend to the Shareholders the adoption of this
        Agreement and the approval of the transactions contemplated
        hereby.  ATI shall use all reasonable efforts to obtain all votes
        and approvals of the Shareholders necessary for the approval and
        adoption of this Agreement and the transactions contemplated
        hereby under the General Corporation Law and its Certificate of
        Incorporation and Bylaws.

             Section 4.3.  Certain Employee Benefits Matters.  

                  (a)  Thermo Instrument expressly reserves the right, at
        no cost to the Shareholders and subject to the terms of any
        pension plan, welfare plan or other benefit plan or program of
        any Acquired Company, to modify or terminate, or to cause to be
        modified or terminated, any such pension plan, welfare plan or
        other benefit plan or program at any time or from time to time
        after the Closing. 

                  (b)  Except as may be otherwise required by ERISA,
        Thermo Instrument will give employees of the Acquired Companies
        credit for service with such Acquired Companies with respect to
        any of Thermo Instrument's benefit plans which have vesting or
        length of service requirements.

                  (c)  All otherwise eligible employees of the Acquired
        Companies will be entitled to participate in any employee stock
        purchase plan adopted from time to time by Thermo Instrument, in
        accordance with the terms thereof.

                  (d)  As permitted by Revenue Procedure 84-77, Thermo
        Instrument shall be responsible to provide employees of the
        Business a statement on Form W-2 covering calendar year 1995.

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        ATI shall provide to Thermo Instrument all records concerning
        1995 compensation and withholding, through the Closing Date, for
        each such employee.

                  (e)  The parties hereto do not intend to create any
        third-party beneficiary rights respecting any employee as a
        result of the provisions herein and specifically hereby deny any
        such intention.   

             Section 4.4.  Expenses.  Each party will bear entirely the
        respective out-of-pocket expenses that it incurs in connection
        with the transactions contemplated hereby including legal and
        accounting fees.  Notwithstanding the foregoing, this Section 4.4
        shall not be construed as relieving any party from any liability
        which it may have for any breach of any representation or
        warranty made by it herein or any failure to perform any
        obligation or comply with any covenant imposed on it herein.

             Section 4.5.  Books and Records; Access.

                  (a)  Books and Records.  For a period of seven years
        (or such longer period as may be required by law or as may be
        reasonably requested by Thermo Instrument as a result of audits,
        tax contests or pending disputes) from the Closing Date, (i) ATI
        shall not dispose of or destroy any of their business records and
        files to the extent they relate primarily to the Business without
        first offering to turn over possession thereof to Thermo
        Instrument, by written notice at least 60 days prior to the
        proposed date of such disposition or destruction; (ii) ATI shall
        allow Thermo Instrument and its representatives access to such
        records and files, during normal working hours at its principal
        place of business or at any location where such records or files
        are stored; and (iii) Thermo Instrument shall have the right, at
        its own expense, to make copies of any such records and files;
        provided, however, that any such access or copying shall be had
        or done in such manner so as not to unreasonably interfere with
        normal conduct of ATI's business.  For a period of seven years
        (or such longer period as may be required by law or as may be
        reasonably requested by ATI as a result of audits, tax contests
        or pending disputes) from the Closing Date, (i) Thermo Instrument
        shall not dispose of or destroy any of their business records or
        files to the extent they relate primarily to the Business as
        conducted prior to the Closing Date without first offering to
        turn over possession thereof to ATI, by written notice at least
        60 days prior to the proposed date of such disposition or
        destruction; (ii) Thermo Instrument shall allow ATI and its
        representatives access to such records and files during normal
        working hours at its principal place of business or at any
        location where such records and files are stored; and (iii) ATI
        shall have the right, at its own expense, to make copies of any
        such records and files; provided, however, that any such access
        or copying shall be had or done in such manner so as not to
        unreasonably interfere with normal conduct of Thermo Instrument's
        business.

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                  (b)  Access.  Each party shall use its best efforts to
        afford the other parties access to (i) in the case of ATI,
        employees of ATI who remain employees of ATI following the
        Closing Date but are familiar with the Business and (ii) in the
        case of Thermo Instrument, employees of the Business, as any such
        other party shall reasonably request for its proper corporate
        purposes, including, without limitation, the defense of legal
        proceedings or the preparation and audit of tax returns.  Such
        access may include interviews or attendance at depositions or
        legal proceedings; provided, however, that in any event all
        out-of-pocket expenses (excluding wage and salaries) reasonably
        incurred by any party in connection with this Section 4.5(b)
        shall be paid or promptly reimbursed by the party requesting such
        services.


                                    ARTICLE 5

                            CONDITIONS TO OBLIGATIONS

             Section 5.1.  Conditions to Obligations of Thermo Instrument
        and Acquisition.  The obligations of Thermo Instrument and
        Acquisition to consummate the transactions contemplated hereby
        are subject to the satisfaction, on or before the Closing, of the
        following conditions (unless waived in writing by Thermo
        Instrument and Acquisition in the manner provided in Section 6.2
        hereof):

                  (a)  Representations, Warranties and Performance of
        ATI.  The representations and warranties set forth in Section 3.2
        of the TMD Agreement shall be accurate on and as of the date
        hereof, and on and as of the Closing Date as though made on and
        as of the Closing Date (except to the extent necessary to reflect
        the consummation of the transactions contemplated by the TMD
        Agreement), and ATI shall have performed all obligations and
        complied with all covenants required to be performed or to be
        complied with by it under this Agreement and the TMD Agreement
        prior to the Closing.  ATI shall be permitted to deliver a
        revised Disclosure Schedule (as defined in the TMD Agreement) to
        TMD at any time prior to the Closing, provided, however, that
        Thermo Instrument shall be afforded not less than five business
        days prior to the Closing to review any such revised Disclosure
        Schedule and provided, further, that Thermo Instrument shall be
        entitled to terminate this Agreement and its obligations
        hereunder pursuant to Section 6.3 hereof in the event that any
        such additional or revised disclosure has or could have, in the
        sole judgment of Thermo Instrument, an adverse effect on the
        financial condition, assets, liabilities, earnings, business or
        prospects of ATI.

                  (b)  Authorization.  All action necessary to authorize
        the execution, delivery and performance hereof by ATI and the
        consummation of the transactions contemplated hereby, including

                                       12
PAGE






        the approval by the Shareholders of the execution, delivery and
        performance of this Agreement and the transactions contemplated
        hereby in accordance with the General Corporation Law shall have
        been duly and validly taken by ATI.  ATI shall have furnished
        Thermo Instrument with a copy of all resolutions adopted by its
        Board of Directors and Shareholders in connection with such
        actions, certified by the Secretary or an Assistant Secretary of
        ATI, together with copies of such other instruments and documents
        as Thermo Instrument shall have reasonably requested.  

                  (c)  TMD Transaction.  All conditions precedent to the
        consummation of the TMD Transaction (other than the consummation
        of the transactions contemplated by this Agreement) shall have
        been satisfied or waived pursuant to the TMD Agreement.

                  (d)  Consents.  Any governmental authority having
        jurisdiction over any Acquired Company, Thermo Instrument or
        Acquisition or any other person in any contractual or other
        relationship with any Acquired Company, to the extent that its
        consent or approval is required by applicable law or regulation
        or any applicable contract or other instrument for the
        performance of this Agreement or the consummation of the
        transactions contemplated hereby or for the continuation of any
        existing contractual relationship with any Acquired Company,
        shall have granted any necessary consent or approval.

                  (e)  Good Standing Certificates.  ATI and each Acquired
        Company (to the extent that each such Acquired Company is
        organized in a jurisdiction where such certificates are generally
        available) shall have delivered to Thermo Instrument a long-form
        corporate good standing certificate from its jurisdiction of
        incorporation (or equivalent evidence of each such Acquired
        Company's status in the case of certain foreign jurisdictions)
        and good standing certificates from each jurisdiction in which
        ATI or such Acquired Company is qualified to transact business
        (or equivalent evidence of each such Acquired Company's status in
        the case of certain foreign jurisdictions).

                  (f)  Officer's Certificate.  ATI shall have delivered
        to Thermo Instrument a certificate executed by an officer of ATI,
        dated the Closing Date, certifying to the fulfillment of the
        conditions specified in Section 5.1(a).

                  (g)  Legal Opinion of Counsel for ATI.  Thermo
        Instrument shall have received an opinion of Sonnenschein Nath &
        Rosenthal, counsel for ATI, dated the Closing Date and in the
        form attached hereto as Exhibit D, together with such other
        opinions of counsel to the Acquired Companies as Thermo
        Instrument may reasonably require.

                  (h)  No Litigation or Proceedings with Respect to this
        Agreement.   No legal action or other proceedings to restrain or
        prohibit the consummation of the transactions contemplated by
        this Agreement shall be pending or threatened.  

                                       13
PAGE







                  (i)  Documents Satisfactory.  The form and substance of
        all legal matters contemplated herein and of all papers used or
        delivered hereunder shall be reasonably acceptable to Thermo
        Instrument, and Thermo Instrument shall have received all
        documents that it may have reasonably requested in connection
        with the transactions contemplated hereby, in form and substance
        reasonably satisfactory to it.

             Section 5.2.  Conditions to Obligations of ATI.  The
        obligations of ATI to consummate the transactions contemplated
        hereby are subject to the satisfaction, on or before the Closing,
        of the following conditions (unless waived by ATI in writing in
        the manner provided in Section 6.2 hereof):

                  (a)  Performance of Covenants.  Thermo Instrument and
        Acquisition shall have performed all obligations and complied
        with all covenants required to be performed or to be complied
        with by them under this Agreement prior to the Closing.

                  (b)  Authorization.  All action necessary to authorize
        the execution, delivery and performance hereof by Thermo
        Instrument and Acquisition and the consummation of the
        transactions contemplated hereby shall have been duly and validly
        taken by Thermo Instrument and Acquisition.  Thermo Instrument
        and Acquisition shall have furnished ATI with a copy of all
        resolutions adopted by the Board of Directors of Thermo
        Instrument and Acquisition in connection with such actions,
        certified by the Secretary or an Assistant Secretary of Thermo
        Instrument and Acquisition, respectively, together with copies of
        such other instruments and documents as ATI shall have reasonably
        requested. 

                  (c)  Consents.  Any governmental authority having
        jurisdiction over ATI, to the extent that its consent or approval
        is required by applicable law or regulation for the performance
        of this Agreement or the consummation of the transactions
        contemplated hereby, shall have granted any necessary consent or
        approval.

                  (d)  Permits and Approvals.  Any and all consents,
        permits, approvals or other actions of any person, jurisdiction
        or authority required in the reasonable opinion of counsel for
        ATI for lawful consummation of the transactions contemplated
        hereby shall have been obtained, and shall be in full force and
        effect, and no such consent, permit, approval or other action
        shall contain any provision that in the reasonable judgment of
        such counsel is unduly burdensome.

                  (e)  ATI Shareholder Approval.  The approval by the
        Shareholders of the execution, delivery and performance of this
        Agreement and the transactions contemplated hereby in accordance
        with the General Corporation Law shall have been duly and validly
        obtained.

                                       14
PAGE







                  (f)  Good Standing Certificates.  Each of Thermo
        Instrument and Acquisition shall have delivered to ATI a
        corporate good standing certificate from its jurisdiction of
        incorporation.

                  (g)  Officer's Certificate.  Thermo Instrument shall
        have delivered to ATI a certificate executed by an officer of
        Thermo Instrument, dated the Closing Date, certifying to the
        fulfillment of the conditions specified in Section 5.2(a).

                  (h)  No Litigation or Proceedings with Respect to this
        Agreement.  No legal action or other proceedings to restrain or
        prohibit the consummation of the transactions contemplated by
        this Agreement shall be pending or threatened.

                  (i)  Documents Satisfactory.  The form and substance of
        all legal matters contemplated herein and of all papers used or
        delivered hereunder shall be reasonably acceptable to counsel for
        ATI and ATI shall have received all documents that such counsel
        may have reasonably requested in connection with the transactions
        contemplated hereby, in form and substance reasonably
        satisfactory to such counsel.

                  (j)  Legal Opinion of Thermo Instrument's Counsel.  ATI
        shall have received an opinion of Thermo Instrument's general
        counsel, dated the Closing Date and in the form attached hereto
        as Exhibit E.


                                    ARTICLE 6

                      MODIFICATION, WAIVER AND TERMINATION

             Section 6.1.  Modifications and Amendments.  The parties may
        mutually amend any provision of this Agreement at any time prior
        to the Closing Date; provided, however, that any amendment
        effected subsequent to the approval of this Agreement by the
        Shareholders shall be subject to the restrictions contained in
        the General Corporation Law.  No amendment of any provision of
        this Agreement shall be valid unless the same shall be in writing
        and signed by all of the parties.

             Section 6.2.  Waivers.  The parties hereto may, by a written
        signed instrument, extend the time for or waive the performance
        of any of the obligations of another party hereto or waive
        compliance by such other party with any of the covenants or
        conditions contained herein.

             Section 6.3.  Termination.  At any time prior to the
        Closing, this Agreement may be terminated (a) by mutual consent
        of Thermo Instrument and Acquisition, on the one hand, and ATI on
        the other; (b) by Thermo Instrument and Acquisition if (i) there
        has been a material breach by ATI of a covenant, representation

                                       15
PAGE






        or warranty contained in this Agreement or in the TMD Agreement;
        (ii) Thermo Instrument has notified ATI in writing of the
        existence of such breach; and (iii) the party in breach has
        failed to cure such breach within a reasonable period of time
        after receiving such notice; (c) by ATI if (i) there has been a
        material breach by Thermo Instrument or Acquisition of a
        covenant, representation or warranty contained in this Agreement;
        (ii) ATI has notified Thermo Instrument in writing of the
        existence of such breach; and (iii) Thermo Instrument or
        Acquisition, as the case may be, has failed to cure such breach
        within 30 days after receiving such notice; (d) by ATI, Thermo
        Instrument or Acquisition if (i) there shall be an order of a
        court in effect preventing consummation of the transactions
        contemplated by this Agreement or (ii) there shall be any action
        taken, or any statute, rule, regulation or order enacted,
        promulgated, issued or deemed applicable to this Agreement, by a
        governmental authority that would make consummation of the
        transactions contemplated by this Agreement illegal; (e) by ATI,
        Thermo Instrument or Acquisition if the Closing does not occur by
        November 30, 1995; or (f) by Thermo Instrument or Acquisition if
        (i) ATI shall have elected to revise the Disclosure Schedule
        pursuant to Section 5.1(a) hereof and (ii) in the sole judgment
        of Thermo Instrument, any such additional or revised disclosure
        has or could have an adverse effect on the financial condition,
        assets, liabilities, earnings, business or prospects of ATI.

             Section 6.4.  Effect of Termination.  If this Agreement
        shall be terminated as provided in Section 6.3, this Agreement
        shall forthwith become void (except as otherwise provided in
        Section 4.4); provided, however, that the foregoing shall not
        relieve any party from liability for damages actually incurred as
        a result of any breach of this Agreement.


                                    ARTICLE 7

                                     GENERAL

             Section 7.1.  Notices.  All notices, requests, demands,
        consents and other communications which are required or permitted
        hereunder shall be in writing, and shall be deemed given when
        actually received or if earlier, one day after deposit with a
        nationally recognized air courier or express mail, charges
        prepaid or three days after deposit in the U.S. mail by certified
        mail, return receipt requested, postage prepaid, addressed as
        follows:

             If to Thermo Instrument or Acquisition:

                  Thermo Instrument Systems Inc.
                  c/o Thermo Jarrell Ash Corporation
                  27 Forge Parkway
                  Franklin, Massachusetts  02038
                  Attention:  President

                                       16
PAGE







             With a copy to:

                  Thermo Electron Corporation
                  81 Wyman Street
                  Waltham, Massachusetts  02254
                  Attention:  General Counsel

             If to ATI, to:

                  Analytical Technology, Inc.
                  The Schrafft Center
                  529 Main Street
                  Boston, Massachusetts  02129
                  Attention:  President

             With copies to:

                  Sonnenschein Nath & Rosenthal
                  Suite 8000 Sears Tower
                  233 South Wacker Drive
                  Chicago, IL  60606
                  Attention:  J. Ross Docksey, Esq.

             and to: 

                  Thermo Electron Corporation
                  81 Wyman Street
                  Waltham, Massachusetts  02254
                  Attention:  General Counsel

        or to such other address as any party hereto may designate in
        writing to the other parties, specifying a change of address for
        the purpose of this Agreement.

             Section 7.2.  Entire Agreement.  This Agreement supersedes
        any and all oral or written agreements or understandings
        heretofore made relating to the subject matter hereof (including
        without limitation the Letter of Intent executed by Thermo
        Instrument's parent company, Thermo Electron Corporation, and ATI
        dated July 19, 1995) and constitutes the entire agreement of the
        parties relating to the subject matter hereof.

             Section 7.3.  Parties in Interest.  All covenants and
        agreements, representations and warranties contained in this
        Agreement made by or on behalf of any of the parties hereto shall
        bind and inure to the benefit of the parties hereto, and their
        respective successors, assigns, heirs, executors, administrators
        and personal representatives, whether so expressed or not.

             Section 7.4.  No Implied Rights or Remedies.  Except as
        otherwise expressly provided herein, nothing herein expressed or
        implied is intended or shall be construed to confer upon or to
        give any person, firm or corporation, other than the parties

                                       17
PAGE






        hereto, any rights or remedies under or by reason of this
        Agreement.

             Section 7.5.  Headings.  The headings in this Agreement are
        inserted for convenience of reference only and shall not be a
        part of or control or affect the meaning hereof.

             Section 7.6.  Severability.  If any provision of this
        Agreement shall be declared void or unenforceable by any judicial
        or administrative authority, the validity of any other provision
        shall not be affected thereby.

             Section 7.7.  Counterparts.  This Agreement may be executed
        in two or more counterparts, each of which shall be deemed an
        original, but all of which together shall constitute one and the
        same instrument.

             Section 7.8.  Exhibits.  The Exhibits attached hereto and
        referred to in this Agreement are a part of this Agreement for
        all purposes.

             Section 7.9.  Assignment.  This Agreement and the rights and
        duties hereunder shall be binding upon and inure to the benefit
        of the successors, assigns, heirs and legal and personal
        representatives of the parties hereto, but shall not be
        assignable or delegable by any party without the prior written
        consent of the other parties and any purported assignment without
        such prior written consent shall be null and void, except that
        Thermo Instrument and Acquisition may assign this Agreement, or
        rights and duties hereunder, after the Closing Date.

             Section 7.10.  Further Assurances.  ATI will execute and
        furnish to Thermo Instrument and Acquisition all documents and
        will do or cause to be done all other things that Thermo
        Instrument or Acquisition may reasonably request from time to
        time in order to give full effect to this Agreement and to
        effectuate the intent of the parties.

             Section 7.11.  Gender.  In this Agreement, unless the
        context requires otherwise the singular includes the plural, the
        plural the singular, the masculine gender includes the neuter,
        masculine and feminine genders and vice versa.

             Section 7.12.  Public Announcement.  The content and timing
        of any public announcement pertaining to this Agreement shall be
        subject to the prior agreement and approval of Thermo Instrument
        and ATI.

             Section 7.13.  Governing Law.  This Agreement shall be
        governed by the law of the State of Delaware applicable to
        agreements made and to be performed wholly within such
        jurisdiction, without regard to the conflicts of laws provisions
        thereof.    


                                       18
PAGE






             IN WITNESS WHEREOF, the parties have caused this Agreement
        to be duly executed as of the date first written above.


                                      THERMO INSTRUMENT SYSTEMS INC.

        [Seal]                        By: /s/ Jonathan W. Painter

                                      Title: Treasurer



                                      ATI ACQUISITION CORP.

        [Seal]                        By: /s/ Jonathan W. Painter

                                      Title: Treasurer



                                      ANALYTICAL TECHNOLOGY, INC.

        [Seal]                        By: /s/ William J. Kennedy

                                      Title: Chairman and Chief Executive
                                             Officer


        Thermedics Inc. hereby joins this Agreement as a party for
        purposes of the rights and obligations set forth in Section 1.3
        hereof.


                                      THERMEDICS INC.

        [Seal]                        By: /s/ John W. Wood, Jr. 

                                      Title: President





        AA953410015











                                       19