THIRD AMENDMENT OF LEASE


             THIS THIRD AMENDMENT OF LEASE is made as of the 30th day of
        September, 1996, 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 HOLOMETRIX, INC., a
        Delaware corporation having a principal office at 25 Wiggins
        Avenue, Bedford, Massachusetts and Tytronics Incorporated, a
        Massachusetts corporation having a principal place of business at
        25 Wiggins Avenue, Bedford, Massachusetts, (together the
        "Lessee").

                                 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 Lessee 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 and by Second
        Amendment of Lease (the "Second Amendment") dated January 15,
        1995 (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, 1996 and expiring on September 30,
        1999; provided, however, that from and after October 1, 1997,
        Lessor and Lessee shall each have the right to terminate the
        Lease, by 90 days written notice to the other.

             2.   Base Rent under Article III, Section 1 of the Lease is
        revised as follows; Annually, for the period October 1, 1996
        through September 30, 1997, the amount of Sixty Eight Thousand
        Four Hundred ($68,400) Dollars payable in equal monthly
        installments of Five Thousand Seven Hundred ($5,700) Dollars; for
        the period October 1, 1997 through September 30, 1998, the amount
        of Seventy Six Thousand ($76,000) Dollars, payable in equal<PAGE>




        monthly installments of Six Thousand Three Hundred Thirty Three
        and Thirty Three One Hundredths ($6,333.33) Dollars; and for the
        period October 1, 1998 through September 30, 1999, the amount of
        Eighty Three Thousand Six Hundred ($83,600) Dollars payable in
        equal monthly installments of Six Thousand Nine Hundred Sixty-six
        and Sixty-six One Hundredths ($6,966.66) Dollars.

             3.   Section 2 of the Second Amendment is hereby deleted.

             4.   Article XXII, Section 11 of the Lease is hereby deleted
        and replaced by the following:

        Assignment or Subletting.  (a)  Lessee shall not mortgage,
        pledge, hypothecate, or assign this Lease or sublease the
        Premises or any portion thereof (which term shall be deemed to
        include any arrangement pursuant to which a third party is
        permitted by Lessee to occupy all or any portion of the
        Premises), without obtaining, an each occasion, the prior written
        consent of Lessor, which consent may be given or withheld in
        Lessor's sole discretion.

        (b)  If Lessee wishes to assign this Lease or sublease all or any
        portion of the Premises, Lessee shall so notify Lessor in writing
        and request Lessor's consent thereto.  Such notice shall include
        (i) the name of the proposed assignee or sublessee, (ii) a
        general description of the types of business conducted by the
        proposed assignee or sublessee and a reasonably detailed
        description of the business operations proposed to be conducted
        in the Premises by such person or entity, (iii) such financial
        information concerning the proposed assignee or sublessee as
        Lessor may reasonably require, and (iv) all terms and provisions
        upon which such assignment or sublease is proposed to be made.
        Lessor shall have twenty (20) days from the day on which it
        receives Lessee's notice and such require information to give
        notice to Lessee that either (i) Lessor consents to such
        assignment or sublease, or (ii) Lessor withholds its consent to
        such assignment or sublease, or (iii) where applicable, Lessor is
        exercising its right of recapture pursuant to paragraph (e)
        below.

        (c)  If Lessor consents to an assignment or sublease:  (i) Lessee
        shall promptly deliver to Lessor a fully executed copy of said
        assignment or sublease; (ii) Lessee shall remain primarily liable
        to Lessor hereunder (which liability shall be joint and several
        with the assignee or sublessee); and (iii) if the aggregate rent
        and other amounts payable to Lessee under or in connection with
        such assignment or sublease, after deduction of the costs
        reasonably incurred by Lessee in entering into such assignment or
        sublease (including, without limitation, reasonable attorneys'
        fees, brokerage commissions and alteration costs amortized on a
        straight-line basis over the term of such sublease), exceeds the
        rent and other amounts payable hereunder, Lessee shall pay to
        Lessor, as Additional Rent, one-half (1/2) of the amount of such
        excess immediately upon receipt thereof by Lessee.

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        (d)  If Lessor withholds its consent to such assignment or
        sublease, Lessee shall not enter into the proposed assignment or
        sublease with such person or entity.

        (e)  If Lessor so elects, it shall have the right to consider
        Lessee's request for Lessor's consent to any assignment of the
        Lease, or a request for Lessor's consent to a sublease, as an
        offer to Lessor to release from this Lease that portion of the
        Premises which is proposed to be the subject of such sublease for
        the term of such proposed sublease or, in the case of a proposed
        assignment of this Lease, the entire Premises for the entire
        Lease Term.  If Lessor accepts such offer, then (i) in the case
        of a proposed sublease, this Lease shall be deemed to be amended
        as of the proposed effective date of such sublease so as to
        delete the portion of the Premise which would have been subject
        thereto from the Premises for purposes of this Lease (with a
        commensurate adjustment in Rent and the percentage representing
        Lessee's Proportionate Share) for the remaining term of the
        Lease, or (ii) in the case of a proposed assignment, this Lease
        shall terminate as of the proposed effective date of such
        assignment as if such date was the last day of the Lease Term.

        (f)  Regardless of whether Lessor grants such consent, Lessee
        shall reimburse Lessor on demand, as Additional Rent, for all out
        of pocket costs and expenses (including, without limitation,
        attorneys' fees) reasonably incurred by Lesser in responding to a
        request for such consent,

        (g)  Lessee shall not be entitled to enter into any assignment or
        sublease, or to request Lessor's consent thereto, during the
        continuance of an Event of Default hereunder by Lessee.

        (h)  Any assignment or sublease entered into pursuant to this
        Section shall be subject to all or the terms and provisions of
        the Lease, including without limitation this Section.  If Lessee
        enters into any such assignment or sublease, Lessor may, at any
        time and from time to time after the occurrence of a default
        hereunder, collect rent from such assignee or sublessee, and
        apply the net amount collected against Lessee's obligations
        hereunder, but no such assignment or sublease or collection shall
        be deemed an acceptance by Lessor of such assignee or sublessee
        as a lessee hereunder or as a release of the original named
        Lessee hereunder.

             5.   Section 4 of the Second Amendment is revised by adding
        the following:

             If Lessor requires use of the storage area shown on
        Exhibit A to the Second Amendment, Lessee shall vacate the same
        upon 90 days written notice by Lessor.  Further, Lessor agrees to
        maintain the storage area in a safe and neat condition.  If
        Lessee is notified by any authority that the storage area is in
        violation of any law or regulation, Lessee shall immediately
        notify Lessor of the same.  If such violation is not cured within

                                      - 3 -<PAGE>




        forty-eight (48) hours of Lessee's receipt of notification
        thereof, or such shorter time as set forth in the notice to
        Lessee, all of Lessee's rights to the storage area shall
        terminate immediately.  Since Lessee's access to the storage area
        is hereby limited, stored items should only be those needed on an
        infrequent basis.

             6.   Lessee shall maintain the grounds outside in a neat and
        orderly manner, keep the loading dock clear of all obstructions,
        keep all trash in containers and retrain from feeding animals.

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

                                           LESSOR:

                                           OPTA FOOD INGREDIENTS, INC.



                                           By: /s/ Scott A. Kumf, CFO
                                           (Title)

                                           LESSEE:

                                           HOLOMETRIX, INC.



                                           By:_/s/ Gary E. Coutard,
                                           Manager, Finance and
                                           Administration_____
                                                     (Title)

                                           TYTRONICS INCORPORATED



                                           By:_/s/ Gary E. Coutard,
                                           Manager, Finance and
                                           Administration________
                                                     (Title)













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