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                                                                      EXHIBIT 4


         SECOND SUPPLEMENTAL INDENTURE, dated as of January 31, 1997, between
CABOT CORPORATION, a corporation duly organized and existing under the laws of
the State of Delaware (herein called the "Company"), having its principal
executive offices at 75 State Street, Boston, Massachusetts, and THE STATE
STREET BANK AND TRUST COMPANY, a Massachusetts trust company (herein called the
"Trustee"), having its principal corporate trust office at Two International
Place, Boston, Massachusetts 02110.


                                    RECITALS

         WHEREAS, the Company has entered into an Indenture dated as of December
1, 1987 and supplemented by a First Supplemental Indenture dated June 17, 1992
(as the same may be modified by the Trust Indenture Reform Act of 1990, the
"Indenture"), with The First National Bank of Boston, as the Trustee's
predecessor, to provide for the issuance from time to time of the Company's
Securities, to be issued in one or more series; and

         WHEREAS, Section 9.01 of the Indenture provides, among other things,
that the Company and the Trustee may enter into indentures supplemental to the
Indenture to cure any ambiguity, omission, defect or inconsistency or to make
other formal changes and to make any change that does not adversely affect the
rights of any Securityholder; and

         WHEREAS, the Trustee became the successor to The First National Bank of
Boston, as Trustee under the Indenture, pursuant to Section 7.09 of the
Indenture; and

         WHEREAS, all conditions have been complied with, all actions have been
taken and all things have been done which are necessary to make this Second
Supplemental Indenture a valid and binding supplement to the Indenture.

         NOW, THEREFORE, THIS SECOND SUPPLEMENTAL INDENTURE WITNESSETH:

         For and in consideration of the premises and the purchase of the
Securities by the holders thereof, it is mutually covenanted and agreed, for the
equal and proportionate benefit of all holders of Securities, as follows:

         Section 1. Definitions. Capitalized terms not defined herein shall have
their associated meanings as defined in the Indenture.

         Section 2. Successor Trustee. The Trustee succeeded The First National
Bank of Boston, as Trustee under the Indenture, pursuant to Section 7.09 of the
Indenture, with effect from and after October 2, 1995 (the "Effective Date").

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         Section 3. Incorporation of Indenture. From and after the date hereof,
the Indenture, as supplemented and amended by this Second Supplemental
Indenture, shall be read, taken and construed as one and the same instrument
with respect to the Securities.

         Section 4. Acceptance of Trust. The Trustee accepts the trusts created
by the Indenture, from and after the Effective Date, as supplemented by this
Second Supplemental Indenture, and agrees to perform the same upon the terms and
conditions in the Indenture, as supplemented by this Second Supplemental
Indenture.

         Section 5. Counterparts. This Second Supplemental Indenture may be
executed in any number of counterparts, each of which when so executed shall be
deemed to be an original, but all such counterparts shall together constitute
but one and the same instrument.


         IN WITNESS WHEREOF, the parties hereto have caused this Second
Supplemental Indenture to be duly executed, and their respective seals to be
hereunto affixed and attested, all as of the date first above written.



                                             CABOT CORPORATION

                                             BY:  /s/ Kenyon C. Gilson
                                                ----------------------
                                                    Kenyon C. Gilson,
                                                    Executive Vice President and
                                                    Chief Financial Officer

ATTEST:

/s/ Edith C. McGuinness
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Edith C. McGuinness
Assistant Secretary
                                             THE STATE STREET BANK AND
                                                 TRUST COMPANY, as Trustee

                                             BY: /s/ Henry W. Seemore
                                                 --------------------
                                                    Henry W. Seemore,
                                                    Assistant Vice President

ATTEST:


/s/ Eric J. Donaghey
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