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                                                                    EXHIBIT 4.2




                         FORM OF REVOLVING CREDIT NOTE



$_________                                                    New York, New York
                                                                    July 9, 1996


     FOR VALUE RECEIVED, each of the undersigned, Sybron International
Corporation ("Parent"), a Wisconsin corporation, Kerr Corporation ("Kerr"), a
Delaware Corporation, and Nalge Company ("Nalge"), a Delaware Company (each, a
"Revolving Credit Borrower"), severally, hereby unconditionally promises to pay
to the order of __________________(the "Lender") at the office of Chemical Bank,
located at 270 Park Avenue, New York, New York 10017, in lawful money of the
United States of America and in immediately available funds, on the Termination
Date the lesser of (a) the principal amount of                  DOLLARS
($_______), and (b) the aggregate unpaid principal amount of all Revolving
Credit Loans made by the Lender to such Revolving Credit Borrower pursuant to
subsection 2.1 of the Credit Agreement, as hereinafter defined.  Each Revolving
Credit Borrower, severally, further agrees to pay interest in like money at
such office on the unpaid principal amount of Revolving Credit Loans of such
Revolving Credit Borrower from time to time outstanding at the rates and on the
dates specified in subsection 2.14 of such Credit Agreement.

     The holder of this Note is authorized to endorse on the appropriate
schedules annexed hereto and made a part hereof or on a continuation thereof
which shall be attached hereto and made a part hereof the date, Type and amount
of each Revolving Credit Loan made by such holder to each Revolving Credit
Borrower pursuant to the Credit Agreement and the date and amount of each
payment or prepayment of principal thereof, each continuation thereof, each
conversion of all or a portion thereof to another Type and, in the case of
Eurodollar Loans, the length of each Interest Period and the Eurodollar Rate
with respect thereto.  Each such endorsement shall constitute prima facie
evidence of the accuracy of the information endorsed. The failure to make any
such endorsement shall not affect the obligations of the Revolving Credit
Borrower in respect of such Revolving Credit Loan.

     This Note (a) is one of the Revolving Credit Notes referred to in the
Credit Agreement, dated as of July 31, 1995 (as amended, supplemented or
otherwise modified from time to time, the "Credit Agreement"), among the
Parent, Kerr, Nalge, Ormco Corporation, a Delaware corporation, Erie Scientific
Company, a Delaware corporation, Barnstead Thermolyne Corporation, a Delaware
corporation, the Lender, the other banks and financial institutions from time
to time parties thereto, Chemical Securities Inc., as arranger, and Chemical
Bank, as


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administrative agent, (b) is subject to the provisions of the Credit Agreement
and (c) is subject to optional and mandatory prepayment in whole or in part as
provided in the Credit Agreement.  This Note is secured and guaranteed as
provided in the Loan Documents.  Reference is hereby made to the Loan Documents
for a description of the assets in which a security interest has been granted,
the nature and extent of the security and the guarantees, the terms and
conditions upon which the security interests and each guarantee were granted
and the rights of the holder of this Note in respect thereof.

     Upon the occurrence of any one or more of the Events of Default, all
amounts then remaining unpaid on this Note shall become, or may be declared to
be, immediately due and payable, all as provided in the Credit Agreement.

     All parties now and hereafter liable with respect to this Note, whether
maker, principal, surety, guarantor, endorser or otherwise, hereby waive
presentment, demand, protest and all other notices of any kind, except as
otherwise provided in any of the Loan Documents.

     Unless otherwise defined herein, terms defined in the Credit Agreement and
used herein shall have the meanings given to them in the Credit Agreement.

     THIS NOTE SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN
ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.


                                                SYBRON INTERNATIONAL CORPORATION



                                                By:__________________________
                                                   
                                                Name:________________________

                                                Title:


                                                KERR CORPORATION



                                                By:____________________________
                                                
                                                Name:__________________________

                                                Title:_________________________




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                                 NALGE COMPANY



                                      By:__________________________

                                     Name:_________________________

                                     Title:________________________


















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                                                                    Schedule A-1
                                                        to Revolving Credit Note


                                     PARENT
                 LOANS, CONVERSIONS AND REPAYMENTS OF ABR LOANS




                              Amount                           Amount of ABR Loans   Unpaid Principal
                           Converted to  Amount of Principal   Converted to          Balance of ABR
Date  Amount of ABR Loans   ABR Loans    of ABR Loans Repaid     Eurodollar Loans    Loans                 Notation Made By
                                                                                         






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                                                                                                               Schedule A-2
                                                                                                   to Revolving Credit Note


                                                               KERR
                                          LOANS, CONVERSIONS AND REPAYMENTS OF ABR LOANS



                              Amount                           Amount of ABR Loans   Unpaid Principal
                           Converted to  Amount of Principal   Converted to          Balance of ABR
Date  Amount of ABR Loans   ABR Loans    of ABR Loans Repaid     Eurodollar Loans    Loans                 Notation Made By
                                                                                         






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                                                                    Schedule A-3
                                                        to Revolving Credit Note


                                     NALGE
                 LOANS, CONVERSIONS AND REPAYMENTS OF ABR LOANS





                              Amount                           Amount of ABR Loans      Unpaid Principal
                           Converted to  Amount of Principal       Converted to          Balance of ABR
Date  Amount of ABR Loans   ABR Loans    of ABR Loans Repaid     Eurodollar Loans             Loans             Notation Made By
                                                                                                





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                                                                    Schedule B-1
                                                        to Revolving Credit Note

                                     PARENT
      LOANS, CONTINUATIONS, CONVERSIONS AND REPAYMENTS OF EURODOLLAR LOANS






                                           Interest Period and                          Amount of
                                             Eurodollar Rate   Amount of Principal  Eurodollar Loans  Unpaid Principal
         Amount of     Amount Converted to    with Respect     of Eurodollar Loans  Converted to ABR    Balance of         Notation
Date  Eurodollar Loans  Eurodollar Loans        Thereto              Repaid              Loans        Eurodollar Loans     Made By
                                                                                                      





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                                                                    Schedule B-2
                                                        to Revolving Credit Note

                                      KERR
      LOANS, CONTINUATIONS, CONVERSIONS AND REPAYMENTS OF EURODOLLAR LOANS




                                           Interest Period and                          Amount of
                                             Eurodollar Rate   Amount of Principal  Eurodollar Loans  Unpaid Principal
         Amount of     Amount Converted to    with Respect     of Eurodollar Loans  Converted to ABR    Balance of         Notation
Date  Eurodollar Loans  Eurodollar Loans        Thereto              Repaid              Loans        Eurodollar Loans     Made By
                                                                                                      






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                                                                    Schedule B-3
                                                        to Revolving Credit Note

                                     NALGE
      LOANS, CONTINUATIONS, CONVERSIONS AND REPAYMENTS OF EURODOLLAR LOANS




                                           Interest Period and                          Amount of
                                             Eurodollar Rate   Amount of Principal  Eurodollar Loans  Unpaid Principal
         Amount of     Amount Converted to    with Respect     of Eurodollar Loans  Converted to ABR    Balance of         Notation
Date  Eurodollar Loans  Eurodollar Loans        Thereto              Repaid              Loans        Eurodollar Loans     Made By