EXHIBIT 10.19



                            FOURTH AMENDMENT OF LEASE


         THIS FOURTH AMENDMENT OF LEASE is made as of the 30th day of September,
1999, by and between OPTA FOOD INGREDIENTS, INC., a Delaware corporation, with
an address of 25 Wiggins Avenue, Bedford, Massachusetts (the "Lessor"),
successor in interest to Springfield Institution for Savings and METRISA, INC.,
a Delaware corporation, having a principal office of 25 Wiggins Avenue, Bedford,
Massachusetts (the "Lessee"), successor in interest to Holometrix, Inc. and
Tytronics, Incorporated.

                                R E C I T A L S :

         A. Reference is hereby made to a certain Lease, dated June 28, 1991, by
and between Griffith Bedford Realty Trust, predecessor in interest to
Springfield Institution for Savings as lessor and Holometrix, Inc. and Tytronics
Incorporated as lessee, demising certain premises (the "Premises") located at 25
Wiggins Avenue, Bedford, Middlesex County, Massachusetts, as amended by First
Amendment of Lease (the "First Amendment") dated August 19, 1993, by Second
Amendment of Lease (the "Second Amendment") dated January 15, 1995 and by Third
Amendment of Lease dated September 30, 1996 (the "Third Amendment" and together,
the "Lease");

         B. Lessor and Lessee are the current holders, respectively, of the
landlord and tenant interest under the Lease.

         C. Lessor and Lessee wish to amend the Lease upon such terms and
conditions as are hereinafter provided.

                              A G R E E M E N T S :

         IN CONSIDERATION OF One ($1.00) Dollar, the mutual covenants as
hereinafter contained and other good and valuable consideration, Lessor and
Lessee agree to amend the Lease, effective as of the date hereof, as follows:

          1. The term of the Lease shall be extended for three (3) years,
commencing October 1, 1999 and expiring on September 30, 2002; provided,
however, that on or prior to June 1, 2000, Lessor and Lessee shall each have the
right to notify the other of their intention to terminate the Lease by written
notice to the other or the lease will extend for the period October 1, 2000
through September 30, 2001; and that on or prior to June 1, 2001, Lessor and
Lessee shall each have the right to notify the other of their intention to
terminate the Lease by written notice to the other or the lease will extend for
the period October 1, 2001 through September 30, 2002.

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          2. Base Rend under Article III, Section 1 of the Lease is revised as
follows: Annually, for the period October 1, 1999 through September 30, 2000,
the amount of One Hundred Six Thousand Four Hundred ($106,400.00) Dollars
payable in equal monthly installments of Eight Thousand Eight Hundred Sixty Six
and 67/100 ($8,866.67) Dollars; for the period October 1, 2000 through September
30, 2001, the amount of One Hundred Fourteen Thousand ($114,000.00) Dollars,
payable in equal monthly installments of Nine Thousand Five Hundred ($9,500.00)
Dollars; and for the period October 1, 2001 through September 30, 2002, the
amount of One Hundred Twenty One Thousand Six Hundred ($121,600.00) Dollars
payable in equal monthly installments of Ten Thousand One Hundred Thirty Three
and 33/100 ($10,133.33) Dollars.

          3. In addition to, and not in substitution for, any other obligations
of Lessee under the Lease, Lessee agrees that it shall comply with all laws,
rules, regulations and orders ("Laws") affecting its tenancy, including, without
limitation, those concerning hazardous materials, as defined by state or federal
law. Lessee shall forthwith send Lessor a copy of any notice received by Lessor
concerning any alleged violation of Laws and shall cure any such violation
within the period set forth in such notice or sixty (60) days, whichever is
sooner. If Lessee has not effected a cure within such time, Lessor may, without
in any way being liable to do so, effect such cure and Lessee shall pay Lessor
all amounts so incurred by Lessor, as additional rent, together with interest at
the prime rate of Fleet Bank, N.A., or any successor thereto, within ten (10)
days of invoice by Lessor.

          4. Except as hereinabove amended, the Lease shall remain in full force
and effect.


                                        LESSOR:

                                        OPTA FOOD INGREDIENTS, INC.



                                        By:____________________________________
                                        Title:_________________________________


                                        LESSEE:

                                        METRISA, INC.



                                        By:____________________________________
                                        Title:_________________________________


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