1

                                                               Exhibit 3(a)

                            CERTIFICATE OF AMENDMENT
                            ------------------------

                                       OF
                                       --

                     RESTATED CERTIFICATE OF INCORPORATION
                     -------------------------------------

     CABOT CORPORATION, a corporation organized and existing under and by
virtue of the General Corporation Law of the State of Delaware,

DOES HEREBY CERTIFY:

     FIRST: That the Board of Directors of said Corporation, at a meeting
duly held on November 14, 1986, adopted votes setting forth proposed
amendments to the Restated Certificate of Incorporation of said
Corporation, declaring said amendments to be advisable and recommending
the adoption of said amendments by vote of the stockholders of the
Corporation at its Annual Meeting of Stockholders called for February 13,
1987. The votes setting forth the proposed amendments are as follows:

     VOTED: That it is advisable for this Corporation to amend its
Restated Certificate of Incorporation by the proposed amendments
described below and that this board recommends the adoption of such
proposed amendments by vote of the Corporation at its Annual Meeting of
Stockholders called for February 13, 1987:

a. To delete paragraph (i) of Article EIGHTH and insert in its place the
   new paragraph (i) of Article EIGHTH as follows:

   (i)(1) No director of this corporation shall be personally liable to
   the corporation or its stockholders for monetary damages for breach
   of fiduciary duty as a director, except for liability (i) for any
   breach of the director's duty of loyalty to this corporation or its
   stockholders, (ii) for acts or omissions not in good faith or which
   involve intentional misconduct or a knowing violation of law, (iii)
   under Section 174 of the Delaware General Corporation Law, as the
   same exists or hereafter may be amended, or (iv) for any transaction
   from which the director derived an improper personal benefit. If the
   Delaware General Corporation Law is hereafter amended to authorize
   the further elimination or limitation of this liability of directors,
   then the liability of a director of the corporation, in addition to
   the limitation on personal liability provided herein, shall be
   limited to the fullest extent permitted by the amended Delaware
   General Corporation Law. Any repeal or modification of this Article
   by the stockholders of this corporation shall be prospective only,
   and shall not adversely affect any limitation on the personal
   liability of a director of this corporation for acts or omissions
   prior to such repeal or modification.

   2

       (2) No officer or employee of this corporation shall be liable to
   this corporation for any loss or damage suffered by it on account of
   any action taken or omitted to be taken by him in good faith as an
   officer or employee of this corporation, if such person exercised or
   used the same degree of care and skill as a prudent man would have
   exercised or used under the circumstances in the conduct of his own
   affairs.

       (3) For purposes of determining compliance with this paragraph
   (i) , any director, officer or employee of this corporation shall be
   deemed to have taken actions or omitted to take actions in good faith
   if the action taken or omitted to be taken by him or her was taken or
   omitted in reliance in good faith upon the advice of counsel for this
   corporation, or the books of account or other records of this
   corporation, or reports or information made or furnished to this
   corporation by any official, accountant, engineer, agent, or employee
   of this corporation, or by any independent public accountant or
   auditor, counsel, engineer, appraiser, investment banker or other
   expert retained or employed by this corporation, by the directors, by
   any committee of the board of directors of this corporation or by any
   authorized officer of this corporation.

b. To delete paragraph (j) of Article EIGHTH and insert in its place a
   new paragraph (j) of Article EIGHTH as follows:

   (j) The corporation shall indemnify any 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 (and whether or not by or in the
   right of the corporation) by reason of the fact that he is or was a
   director, officer, employee or agent of the corporation, or is or was
   serving at the request of the corporation as a director, officer,
   employee or agent of another company, partnership, joint venture,
   trust or other enterprise, or is or was serving as a fiduciary of any
   employee benefit plan, fund or program sponsored by the corporation
   or such other company, partnership, joint venture, trust or other
   enterprise, against expenses (including attorneys' fees), judgments,
   fines and amounts paid in settlement actually and reasonably incurred
   by him in connection with such action, suit or proceeding, to the
   extent and under the circumstances permitted by the General
   Corporation Law of The State of Delaware as amended from time to
   time. Such indemnification (unless ordered by a court) shall be made
   as authorized in a specific case upon a determination that
   indemnification of the director, officer, employee or agent is proper
   in the circumstances because he has met the applicable standards of
   conduct set forth in the General Corporation Law of the State of
   Delaware Such determination shall be made (1) by the board of
   directors by a majority vote of a quorum consisting of directors who
   were not parties to such action, suit or proceeding, or (2) if such
   quorum is not obtainable, or even if obtainable a quorum of
   disinterested directors so directs, by independent legal counsel in a
   written opinion, or (3) by the stockholders. The foregoing right of
   indemnification shall not be deemed exclusive of any other rights to
   which those seeking indemnification may be entitled under any by-law,
   agreement, vote of stockholders or disinterested directors or
   otherwise, and shall continue as to a person who has ceased to be a
   director, officer, employee or agent and shall inure to the benefit
   of the heirs, executors and administrators of such a person.

   3

      VOTED That it is advisable for this Corporation to amend its
Restated Certificate of Incorporation by the proposed amendments
described below and that this board recommends the adoption of such
proposed amendments by vote of the Corporation at its Annual Meeting of
Stockholders called for February 13, 1987:

a. To delete paragraph (c) of Article EIGHTH and insert in its place the
   new paragraph (c) of Article EIGHTH as follows:

   (c) By-laws may be made, altered, amended or repealed by (i) the
   affirmative vote of the holders of at least seventy-five percent
   (75%) of the voting power of the shares of the then outstanding
   shares of stock of all classes and series of this corporation
   entitled to vote generally in the election of directors voting
   together as a single class or (ii) a vote of the majority of the
   directors then in office at any annual, regular, or special
   stockholders or directors meeting, called for that purpose, the
   notice of which shall specify the subject matter of the proposed new
   by-law or the alteration, amendment, or repeal of an existing by-law,
   or the articles to be affected thereby. Any by-law whether made,
   altered, amended, or repealed by the stockholders or directors may be
   repealed, amended, further amended, or reinstated, as the case may
   be, by either the stockholders or the directors as aforesaid.

b. To add a new paragraph (k) to Article EIGHTH of the Restated
   Certificate of Incorporation as follows:

   (k) Any action required or permitted to be taken by the stockholders
   of the corporation must be taken at a duly called annual or special
   meeting of the stockholders of the corporation and may not be taken
   by any consent in writing by such stockholders.

c. To delete the last paragraph of Article ELEVENTH commencing with the
   word "Notwithstanding" and insert the following in its place:

   Notwithstanding any provision of law, this restated certificate of
   incorporation or the by-laws of this corporation (and notwithstanding
   the fact that a lesser percentage may be specified by law, this
   restated certificate of incorporation or the by-laws of this
   corporation), and in addition to any affirmative vote of the holders
   of any class of preferred stock of this corporation outstanding or
   any other class of capital stock of this corporation or any series of
   any of the foregoing then outstanding which is required by law or by
   or pursuant to this restated certificate of incorporation, the
   affirmative vote of the holders of seventy--five percent (75%) or more
   of the voting power of the shares of the then outstanding shares of
   stock of all classes and series of this corporation entitled to vote
   generally in the election of directors, voting together as a single
   class, shall be required to alter, amend or repeal paragraph (a),
   (b), (c) or (k) of Article EIGHTH, Article TENTH or this Article
   ELEVENTH of this restated certificate of incorporation or to adopt
   any provision inconsistent therewith.

   4

     SECOND: That thereafter, pursuant to vote of its Board of Directors,
the Annual Meeting of Stockholders of said Corporation was duly called
and held, upon notice in accordance with Section 222 of the General
Corporation Law of the State of Delaware, at which meeting the necessary
number of shares as required by statute were voted in favor of the
amendments.

     THIRD: That said amendments were duly adopted in accordance with the
applicable provision of Section 242 of the General Corporation Law of the
State of Delaware.

     FOURTH: That the capital of said Corporation shall not be reduced
under or by reason of said amendment.

      IN WITNESS WHEREOF, said CABOT CORPORATION has caused this
certificate to be signed by Robert A. Charpie, its Chairman, and attested
by Charles D. Gerlinger, its Assistant Secretary this 13th day of
February, 1987.

ATTEST:                                         CABOT CORPORATION


/s/ Charles D. Gerlinger                     By /s/ Robert A. Charpie
- ------------------------                        ----------------------
Assistant Secretary                             Chairman