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                                                                   EXHIBIT 10.30


                        AMENDMENT TO ASSIGNMENT OF LEASES

       For valuable consideration, the sufficiency of which is hereby
acknowledged, Ferrofluidics Corporation, a Massachusetts business corporation
with a place of business at 40 Simon Street, Nashua, New Hampshire ("Borrower")
hereby amends the Assignment of Leases, previously given by Mortgagor to Bank of
New Hampshire, a bank chartered under the laws of the State of New Hampshire,
with a place of business at 191 Main Street, Nashua, New Hampshire 03060,
("Lender") which Mortgage is dated June 30,1994 and recorded in the Hillsborough
County Registry of Deeds at Book 5551, Page 1020, for the purpose of increasing
the amount secured by said Assignment, as follows

1.     The first Recital paragraph, after the "Witnesseth" clause, is hereby
amended to read as FOLLOWS:

       WHEREAS, Lender has agreed to provide Borrower with lines of credit
       Consisting of: (i) a revolving line of credit loan in the amount of up to
       Eight Million Five Hundred Thousand Dollars ($8,500,000.00) and (ii) a
       line of credit in the amount of up to Five Million Four Hundred Eleven
       Thousand Dollars ($5,411,000.00) pursuant to an agreement with Lender of
       even date herewith ("Reimbursement Agreement"), all as evidenced in the
       Master Term Note of even date in the principal amount of Thirteen Million
       Nine Hundred Eleven Thousand Dollars ('$13,911,000.00) ("Note"):

       In all other respects, the aforesaid Assignment of Leases shall remain in
full force in effect, entitled to its priority in accordance with the original
date of execution and recording.

       IN WITNESS WHEREOF, Borrower has executed this instrument as of this 3rd
day of December, 1996.




WITNESS:                              BORROWER:
                                      FERROFLUIDICS CORPORATION


/s/ Stephen P. Morin                  By: /s/ William B. Ford
- ------------------------                  ------------------------------
Stephen P. Morin                          Name: William B. Ford
                                          Title: Vice President





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STATE OF NEW HAMPSHIRE
COUNTY OF

    On this the 3rd day of December, 1996, before me, the undersigned officer,
personally appeared William B. Ford, who acknowledged himself to be the Vice
President and Chief Financial Officer of Ferrofluidics Corporation,
Massachusetts corporation, and that he, as such Vice President and Chief
Financial Officer, being authorized to do so, executed the foregoing Assignment
of Leases for the purposes therein contained, by signing the name of the
corporation by himself as Vice President and Chief Financial Officer with the
intention that it be effective as of the date first above written.



                                    /s/ Joan C. Deichler
                                    -----------------------------------------
                                    Joan C. Deichler
                                    Justice of the Peace/Notary Public
                                    My Commission Expire Sept. 8, 1999