EXHIBIT 3.15

                                                       STATE OF DELAWARE
                                                       SECRETARY OF STATE
                                                    DIVISION OF CORPORATIONS
                                                   FILED 10:00 AM 07/23/1992
                                                      922055082 - 2071536


                     RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                                  REHEIS, INC.

                            Pursuant to Section 245
                         of the Corporation Law of the
                               State of Delaware

        REHEIS, INC. (hereinafter called the `Corporation'), originally
incorporated under the name of REHEIS CHEMICAL CORPORATION, INC. by original
Certificate of Incorporation filed in the office of the Secretary of State of
the State of Delaware on September 19, 1985, and currently organized and
existing under and by virtue of the General Corporation Law of the State of
Delaware, does hereby certify that the Board of Directors of the Corporation,
at a meeting of the Board of Directors duly called and held, has duly adopted a
resolution, pursuant to Sections 141 and 242 of the General Corporation Law of
the State of Delaware, setting forth an amended and restated Certificate of
Incorporation of the Corporation and declaring said amendment and restatement to
be advisable. The stockholders of the corporation have duly approved said
amendment and restatement by the required vote of such stockholders, adopted by
a written action in lieu of a meeting of such stockholders, all in accordance
with Sections 242, 245 and 228 of the General Corporation Law of the State of







Delaware. The Certificate of Incorporation of the Corporation, as amended and
restated, is as follows:

        FIRST. The name of the Corporation is Reheis, Inc.

        SECOND. The address of its registered office in the State of Delaware
is Corporation Trust Center, 1209 Orange Street, in the City of Wilmington,
County of New Castle. The name of its registered agent at such address is The
Corporation Trust Company.

        THIRD. The nature of the business or purposes to be conducted or
promoted by the Corporation is as follows:

        To engage in any lawful act or activity for which corporations may be
organized under the General Corporation Law of Delaware.

        `FOURTH: The total number of shares of all classes of stock which the
Corporation shall have authority to issue is 300,000 shares, consisting of (i)
275,000 shares of Common Stock, $.01 par value per share (`Common Stock'), and
(ii) 25,000 shares of Preferred Stock, $.01 par value per share (`Preferred
Stock').

        The following is a statement of the designations and the powers,
privileges and rights, and the qualification, limitations or restrictions
thereof in respect of each class of capital stock of the Corporation.

A. COMMON STOCK.

        1. General. The voting, dividend and liquidation rights of the holders
of the Common Stock are subject to and qualified by the rights of the holders of
the Preferred Stock of any series as may be designated by this Board of
Directors upon any issuance of the Preferred Stock of any series.

        2. Voting. The holders of the Common Stock are entitled to one vote for
each share held at all meetings of stockholders (and written actions in lieu of
meetings). There shall be no cumulative voting.

        3. Dividends. Dividends may be declared and paid on the Common Stock
from funds lawfully available therefor as and when determined by the Board of
Directors and subject to any preferential dividend rights of any then
outstanding Preferred Stock.

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        4. Liquidation. Upon the dissolution or liquidation of the Corporation,
whether voluntary or involuntary, holders of Common Stock will be entitled to
receive all assets of the Corporation available for distribution to its
stockholders, subject to any preferential rights of any then outstanding
Preferred Stock.

B. PREFERRED STOCK.

        Preferred Stock may be issued form time to time in one or more series,
each of such series to have such terms as stated or expressed herein and in the
resolution or resolutions providing for the issue of such series adopted by the
Board of Directors of the Corporation, as hereinafter provided. Any shares of
Preferred Stock which may be redeemed, purchased or acquired by the Corporation
may be reissued except as otherwise provided by law. Different series of
Preferred Stock shall not to construed to constitute different classes of
shares for the purposes of voting by classes unless expressly provided.

        Authority is hereby expressly granted to the Board of Directors from
time to time to issue the Preferred Stock in one or more series, and in
connection with the creation of any such series, by resolutions or resolutions
providing for the issue of the shares thereof, to determine and fix such voting
powers, full or limited, or no voting powers, and such designations, preferences
and relative participating, optional or other special rights, and
qualifications, limitations or restrictions thereof, including without
limitation thereof, dividend rights, conversion rights, redemption privileges
and liquidation preferences, as shall be stated and expressed in such
resolutions, all to the full extent now or hereafter permitted by the General
Corporation Law of Delaware. Without limiting the generality of the foregoing,
the resolutions providing for issuance of any series of Preferred Stock may
provide that such series shall be superior or rank equally or be junior to the
Preferred Stock of any other series to the extent permitted by law. No vote of
the holders of the Preferred Stock or Common Stock shall be a prerequisite to
the issuance of any shares of any series of the Preferred Stock authorized by
and complying with the conditions of the Certificate of incorporation, the
right to have such vote being expressly waived by all present and future
holders of the capital stock of the Corporation.'

        FIFTH. [Omitted].

        SIXTH. In furtherance of and not in limitation of powers conferred by
statute, it is further provided:

          1. Election of directors need not be by written ballot.


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          2. The Board of Directors is expressly authorized to adopt, amend or
repeal the By-Laws of the Corporation.

        SEVENTH. Whenever a compromise or arrangement is proposed between this
corporation and its creditors or any class of them and/or between this
corporation and its stockholders or any class of them, any court of equitable
jurisdiction within the State of Delaware may, on the application in a summary
way of this corporation or of any creditor or stockholder thereof, or on the
application of any receiver or receivers appointed for this corporation under
the provisions of section 291 of Title 8 of the Delaware Code or on the
application of trustees in dissolution or of any receiver or receivers appointed
for this corporation under the provisions of section 279 of Title 8 of the
Delaware Code order a meeting of the creditors or class of creditors, and/or of
the stockholders or class of stockholders of this corporation, as the case may
be, to be summoned in such manner as the said court directs. If a majority in
number representing three-fourths in value of the creditors or class of
creditors, and/or of the stockholders or class of stockholders of this
corporation, as the case may be, agree to any compromise or arrangement and to
any reorganization of this corporation as consequence of such compromise or
arrangement, the said compromise or arrangement and the said reorganization
shall, if sanctioned by the court to which the said application has been made,
be binding on all the creditors or class of creditors, and/or on all the
stockholders or class of stockholders, of this corporation, as the case may be,
and also on this corporation.

        EIGHTH. Except to the extent that the General Corporation Law of the
State of Delaware prohibits the elimination or limitation of liability of
directors for breaches of fiduciary duty, no director of the Corporation shall
be personally liable to the Corporation or its stockholders for monetary damages
for any breach of fiduciary duty as a director, notwithstanding any provision of
law imposing such liability. No amendment to or repeal of this provision shall
apply to or have any effect on the liability or alleged liability of any
director of the Corporation for or with respect to any acts or omissions of such
director occurring prior to such amendment.

        NINTH. 1. Actions, Suits and Proceedings Other than by or in the Right
of the Corporation. The Corporation shall indemnify each person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding whether civil, criminal, administrative or
investigative (other than an action by or in the right of the Corporation), by
reason of the fact that he is or was, or has agreed to become, a director or
officer of the Corporation, or is


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or was serving, or has agreed to serve, at the request of the Corporation,
as a director, officer or trustee of, or in a similar capacity with, another
corporation, partnership, joint venture, trust or other enterprise (all
such persons being referred to hereafter as an `Indemnitee'), or by reason
of any action alleged to have been taken or omitted in such capacity, against
all costs, charges and expenses (including attorneys' fees), judgments, fines
and amounts paid in settlement actually and reasonably incurred by him or on his
behalf in connection with such action, suit or proceeding and any appeal
therefrom, if he acted in good faith and in a manner he reasonably believed to
be in, or not opposed to, the best interests of the Corporation, and, with
respect to any criminal action or proceeding, had no reasonable cause to believe
his conduct was unlawful. The termination of any action, suit or proceeding by
judgment, order, settlement, conviction or upon a plea of nolo contendere or
its equivalent, shall not, of itself, create a presumption that the person did
not act in good faith and in a manner which he reasonably believed to be in, or
not opposed to, the best interests of the Corporation, and, with respect to any
criminal action or proceeding, had reasonable cause to believe that his conduct
was unlawful. Notwithstanding anything to the contrary in this Article, except
as set forth in Section 6 below, the Corporation shall not indemnify an
Indemnitee seeking indemnification in connection with proceeding (or part
thereof) initiated by the Indemnitee unless the initiation thereof was approved
by the Board of Directors of the Corporation.

        2. Actions or Suits by or in the Right of the Corporation. The
Corporation shall indemnify any Indemnitee who was or is a party or is
threatened to be made a party to any threatened, pending or completed action or
suit by or in the right of the Corporation to procure a judgment in its favor
by reason of the fact that he is or was, or has agreed to become, a director or
officer of the Corporation, or is or was serving, or has agreed to serve, at
the request of the Corporation, as a director, officer of trustee of, or in a
similar capacity with, another corporation, partnership, joint venture, trust or
other enterprise, or by reason of any action alleged to have been taken or
omitted in such capacity, against all costs, charges and expenses (including
attorneys' fees) and amounts paid in settlement actually and reasonably
incurred by him or on his behalf in connection with such action, suit or
proceeding and any appeal therefrom, if he acted in good faith and in a
manner he reasonably believed to be in, or not opposed to, the best interests of
the Corporation, except that no indemnification shall be made in respect of any
claim, issue or matter as to which such person, shall have been adjudged to be
liable to the Corporation unless and only to the extent that the Court of
Chancery of Delaware or the court in which such action or suit

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was brought shall determine upon application that, despite the adjudication of
such liability but in view of all the circumstances of the case, such person is
fairly and reasonably entitled to indemnity for such costs, charges and expenses
(including attorneys' fees) which the Court of Chancery of Delaware or such
other court shall deem proper.

        3. Indemnification for Costs, Charges and Expenses of Successful
Party. Notwithstanding the other provisions of this Article, to the extent that
an Indemnitee has been successful, on the merits or otherwise, in defense of
any action, suit or proceeding referred to in Sections 1 and 2 of this Article,
or in defense of any claim, issue or matter therein, or on appeal from any such
action, suit or proceeding, he shall be indemnified against all costs, charges
and expenses (including attorneys' fees) actually and reasonably incurred by him
or on his behalf in connection therewith.

        4. Notification and Defense of Claim. As a condition precedent to his
right to be indemnified, the Indemnitee must notify the Corporation in writing
as soon as practicable of any action, suit, proceeding or investigation
involving him for which indemnity will or could be sought. With respect to any
action, suit, proceeding or investigation of which the Corporation is so
notified, the Corporation will be entitled to participate therein at its own
expense and/or to assume the defense thereof at its own expense, with legal
counsel reasonably acceptable to such Indemnitee. After notice from the
Corporation to the Indemnitee of its election so to assume such defense, the
Corporation shall not be liable to the Indemnitee for any legal or other
expenses subsequently incurred by the Indemnitee in connection with such claim,
other than as provided below in this Section 4. The Indemnitee shall have the
right to employ his own counsel in connection with such claim, but the fees and
expenses of such counsel incurred after notice from the Corporation of its
assumption of the defense thereof shall be at the expense of the Indemnitee
unless (i) the employment of counsel by the Indemnitee has been authorized by
the Corporation, (ii) counsel to the Indemnitee shall have reasonably concluded
that there may be a conflict of interest or position on any significant issue
between the Corporation and the Indemnitee in the conduct of the defense of such
action or (iii) the Corporation shall not in fact have employed counsel to
assume the defense of such action, in each of which cases the fees and expenses
of counsel for the Indemnitee shall be at the expense of the Corporation, except
as otherwise expressly provided by this Article. The Corporation shall not be
entitled to assume the defense of any claim brought by or in the right of the
Corporation or as to which counsel for the Indemnitee shall have reasonably made
the conclusion provided for in clause (ii) above.

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        5. Advance of Costs, Charges and Expenses. Subject to the provisions of
Section 6 below, in the event that the Corporation does not assume the defense
pursuant to Section 4 of this Article of any action, suit, proceeding or
investigation of which the Corporation receives notice under this article, any
costs, charges and expenses (including attorneys' fees) incurred by an
Indemnitee in defending a civil or criminal action, suit, proceeding or
investigation or any appeal therefrom shall be paid by the Corporation in
advance of the final disposition of such matter, provided, however, that the
payment of such costs, charges and expenses incurred by an Indemnitee in
advance of the final disposition of such matter shall be made only upon receipt
of an undertaking by or on behalf of the Indemnitee to repay all amounts so
advanced in the event that it shall ultimately be determined that such
Indemnitee is not entitled to be indemnified by the Corporation as authorized
in this Article.

        6. Procedure for Indemnification. Any indemnification or advancement of
expenses pursuant to Section 1, 2, 3 or 5 of this Article shall be made
promptly, and in any event within 60 days after receipt by the Corporation of
the written request of the Indemnitee, unless with respect to requests under
Section 1, 2 or 5 the Corporation determines within such 60-day period that
such indemnitee did not meet the applicable standard of conduct set forth in
Section 1 or 2, as the case may be. Such determination shall be made in each
instance by (a) a majority vote of a quorum of the directors of the Corporation
consisting of persons who are not at that time parties to the action, suit or
proceeding in question ('disinterested directors'), (b) if no such quorum is
obtainable, a majority vote of a committee of two or more disinterested
directors, (c) a majority vote of a quorum of the outstanding shares of stock of
all classes entitled to vote for directors, voting as a single class, which
quorum shall consist of stockholders who are not at that time parties to the
action, suit or proceeding in question, (d) independent legal counsel (who may
be regular legal counsel to the Corporation) appointed for such purpose by vote
of the directors in the manner specified in clause (a) or (b) above, or (e) a
court of competent jurisdiction. The right to indemnification or advances as
granted by this Article shall be enforceable by the Indemnitee in any court of
competent jurisdiction if the Corporation denies such request, in whole or in
part, or if no disposition thereof is made within the 60-day period referred to
above. Such Indemnitee's costs, charges and expenses (including attorneys' fees)
incurred in connection with successfully establishing his right to
indemnification, in whole or in part, in any such proceeding shall also be
indemnified, by the Corporation. Unless otherwise provided by law, the burden of
proving that the

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Indemnitee is not entitled to indemnification or advancement of expenses under
this Article shall be on the Corporation.

        7. Subsequent Amendment. No amendment, termination or repeal of this
Article or of the relevant provisions of the Delaware General Corporation Law or
any other applicable laws shall affect or diminish in any way the rights of any
Indemnitee to indemnification under the provisions hereof with respect to any
action, suit, proceeding or investigation arising out of or relating to any
actions, transactions or facts occurring prior to the final adoption of such
amendment, termination or repeal.

        8. Other Rights. The indemnification and advancement of expenses
provided by this Article shall not be deemed exclusive of any other rights to
which an Indemnitee seeking indemnification or advancement of expenses may be
entitled under any law (common or statutory), agreement or vote of stockholders
or disinterested directors or otherwise, both as to action in his official
capacity and as to action in any other capacity while holding office for the
Corporation, and shall continue as to an Indemnitee who has ceased to be a
director or officer, and shall inure to the benefit of the estate, heirs,
executors and administrators of such Indemnitee. Nothing contained in this
Article shall be deemed to prohibit, and the Corporation is specifically
authorized to enter into, agreements with officers and directors providing
indemnification rights and procedures different from those set forth in this
Article. In addition, the Corporation may, to the extent authorized from time to
time by its Board of Directors, grant indemnification rights to other employees
or agents of the Corporation or other persons serving the Corporation and such
rights may be equivalent to, or greater or less than, those set forth in this
Article.

        9. Partial Indemnification. If an Indemnitee is entitled under any
provision of this Article to indemnification by the Corporation for some or a
portion of the costs, charges and expenses (including attorneys' fees),
judgments, fines or amounts paid in settlement actually and reasonably
incurred by him or on his behalf in connection with any action, suit,
proceeding or investigation and any appeal therefrom but not, however, for the
total amount thereof, the Corporation shall nevertheless indemnify the
Indemnitee for the portion of such costs, charges and expenses (including
attorneys' fees), judgments, fines or amounts paid in settlement to which
such Indemnitee is entitled.

        10. Insurance. The Corporation may purchase and maintain insurance, at
its expense, to protect itself and any director, officer, employee or agent of
the Corporation or another corporation, partnership, joint venture, trust or
other enterprise against any expense, liability or loss incurred by him

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in any such capacity, or arising out of his status as such, whether or not the
Corporation would have the power to indemnify such person against such expense,
liability or loss under the Delaware General Corporation Law.

        11. Merger or Consolidation. If the Corporation is merged into or
consolidated with another corporation and the Corporation is not the surviving
corporation, the surviving corporation shall assume the obligations of the
Corporation under this Article with respect to any action, suit, proceeding or
investigation arising out or relating to any actions, transactions or facts
occurring prior to the date of such merger or consolidation.

        12. Savings Clause. If this Article or any portion hereof shall be
invalidated on any ground by any court of competent jurisdiction, then the
Corporation shall nevertheless indemnify each indemnitee as to any costs,
charges and expenses (including attorneys' fees), judgments, fines and amounts
paid in settlement in connection with any action, suit, proceeding or
investigation, whether civil, criminal or administrative, including an action by
or in the right of the Corporation, to the fullest extent permitted by any
applicable portion of this Article that shall not have been invalidated and to
the fullest extent permitted by applicable law.

        13. Definitions. Terms used herein and defined in Section 145(h) and
Section 145(i) of the Delaware General Corporation Law shall have the
respective meanings assigned to such terms in such Section 145(h) and Section
145(i).

        14. Subsequent Legislation. If the Delaware General Corporation Law is
amended after adoption of this Article to expand further the indemnification
permitted to Indemnities, then the Corporation shall indemnify such persons to
the fullest extent permitted by the Delaware General Corporation Law, as so
amended.

        TENTH. The Corporation reserves the right to amend, alter, change or
repeal any provision contained in this Restated Certificate of Incorporation, in
the manner now or hereafter prescribed by statute and the Certificate of
Incorporation, and all rights conferred upon stockholders herein are granted
subject to this reservation.



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        IN WITNESS WHEREOF, the Corporation has caused its corporate seal to be
affixed hereto and this Restated Certificate of Incorporation to be signed by
its President and attested by its Assistant Secretary this 23rd day of July,
1992.


                                   REHEIS, INC.


                                   By: PHILIP I. WHITE
                                       -----------------------------------
                                       Philip I. White, President

ATTEST:


[signature illegible]
- --------------------------------
Assistant Secretary
(Corporate Seal)


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