EXHIBIT 10.7


     THIS INSTRUMENT IS SECURED BY A DEED OF TRUST, ASSIGNMENT OF PERMITS,
     RENTS AND BENEFITS, SECURITY AGREEMENT AND FIXTURE FILING, DATED AS OF
     JUNE 18, 1991


                       SIXTH AMENDMENT TO CREDIT AGREEMENT


          SIXTH AMENDMENT dated as of September 23, 1995 TO CREDIT AGREEMENT
dated as of March 20, 1991 among RHEOX, INC., a Delaware corporation (the
"Company"); RHEOX INTERNATIONAL, INC., a Delaware corporation (the "Subsidiary
Guarantor"); each of the lenders that is a signatory hereto (individually, a
"Bank" and, collectively, the "Banks"); THE CHASE MANHATTAN BANK (NATIONAL
ASSOCIATION), a national banking association, and THE NIPPON CREDIT BANK, LTD.,
a Japanese banking corporation acting through its New York branch, as co-agents
for the Banks (each in such capacity, a "Co-Agent" and, collectively, the "Co-
Agents"); and THE CHASE MANHATTAN BANK (NATIONAL ASSOCIATION), as administrative
agent for the Banks (in such capacity, together with its successors in such
capacity, the "Administrative Agent"). 

          WHEREAS, the parties hereto are parties to a Credit Agreement dated as
of March 20, 1991 among the Company, the Subsidiary Guarantor, the Banks, the
Co-Agents and the Administrative Agent (as at any time amended or otherwise
modified, the "Credit Agreement"; terms defined therein having their respective
defined meanings when used herein unless otherwise defined herein);

          WHEREAS, the Company has requested that the Credit Agreement be
amended, and the Banks are willing to consent to such amendment upon the terms
and conditions contained herein.

          NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

          SECTION 1.  AMENDMENTS.  The Credit Documents are hereby amended
(effective as provided in Section 3 hereof) as follows:

          A.  The first sentence of the definition of "Revolving Credit
     Termination Date" in Section 1.01 of the Credit Agreement is amended
     to read as follows:

               "'Revolving Credit Termination Date' shall mean
          September 23, 1996."

          B.  Each reference in the Credit Agreement and the other Credit
     Documents to the Credit Agreement shall be deemed to be a reference to the
     Credit Agreement as amended hereby.  Except as expressly provided in this
     Section 1, the Credit Agreement shall remain unchanged and in full force
     and effect.

          SECTION 2.  REPRESENTATIONS AND WARRANTIES.  Each of the Company and
the Subsidiary Guarantor represents and warrants that:

          A.  The execution and delivery of this Amendment by it has been duly
authorized by all necessary corporate action on its part.

          B.  This Amendment has been duly executed and delivered by it, and
each of this Amendment and the Credit Agreement as modified hereby constitutes
its legal, valid and binding obligation enforceable in accordance with its
respective terms subject, however, to the application by a court of general
principles of equity and to the effect of any applicable bankruptcy, insolvency,
reorganization, moratorium or similar laws affecting creditors' rights
generally.

          SECTION 3.  EFFECTIVENESS.  The provisions of Section 1 hereof shall
become effective on the date by which counterparts hereof have been duly
executed by the Company, the Subsidiary Guarantor, the Banks and the
Administrative Agent and delivered to the Administrative Agent and the
Administrative Agent has received evidence reasonably satisfactory to it as to
the truth of the representation contained in Section 2.A hereof.

          SECTION 4.  COUNTERPARTS.  This Amendment may be executed in any
number of counterparts, each of which may be deemed an original but all of which
together shall constitute one and the same instrument.

          SECTION 5.  GOVERNING LAW.  This Amendment shall be governed and
construed in accordance with the laws of the State of New York.

          IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be executed by their respective officers duly authorized as of the date first
above written.

RHEOX, INC.


By                            
  Name:
  Title:

RHEOX INTERNATIONAL, INC.


By
  Name:
  Title:

THE CHASE MANHATTAN BANK
  (NATIONAL ASSOCIATION), as
   Co-Agent and
   Administrative Agent 


By
  Name:
  Title:

THE NIPPON CREDIT BANK, LTD.,
  as Co-Agent


By
  Name:
  Title:

THE CHASE MANHATTAN BANK
  (NATIONAL ASSOCIATION)


By
  Name:
  Title:

THE NIPPON CREDIT BANK, LTD.


By
  Name:
  Title:

VAN KAMPEN MERRITT PRIME
  RATE INCOME TRUST


By
  Name:
  Title:

RESTRUCTURED OBLIGATIONS BACKED
  BY SENIOR ASSETS B.V.

BY CHANCELLOR SENIOR SECURED
  MANAGEMENT, INC., its Portfolio      
Advisor:


By
  Name:
  Title:

STICHTING RESTRUCTURED OBLIGATIONS     
BACKED BY SENIOR ASSETS 2 (ROSA2)

BY CHANCELLOR SENIOR SECURED
  MANAGEMENT, INC., its Portfolio      
Advisor:


By
  Name:
  Title:

GIROCREDIT BANK,
  NEW YORK BRANCH


By
  Name:
  Title:

BANQUE PARIBAS


By
  Name:
  Title:


     THIS INSTRUMENT IS SECURED BY A DEED OF TRUST, ASSIGNMENT OF PERMITS,
     RENTS AND BENEFITS, SECURITY AGREEMENT AND FIXTURE FILING, DATED AS OF
     JUNE 18, 1991


                      SEVENTH AMENDMENT TO CREDIT AGREEMENT


          SEVENTH AMENDMENT dated as of February 2, 1996 TO CREDIT AGREEMENT
dated as of March 20, 1991 among RHEOX, INC., a Delaware corporation (the
"Company"); RHEOX INTERNATIONAL, INC., a Delaware corporation (the "Subsidiary
Guarantor"); each of the lenders that is a signatory hereto (individually, a
"Bank" and, collectively, the "Banks"); THE CHASE MANHATTAN BANK (NATIONAL
ASSOCIATION), a national banking association, and THE NIPPON CREDIT BANK, LTD.,
a Japanese banking corporation acting through its New York branch, as co-agents
for the Banks (each in such capacity, a "Co-Agent" and, collectively, the "Co-
Agents"); and THE CHASE MANHATTAN BANK (NATIONAL ASSOCIATION), as administrative
agent for the Banks (in such capacity, together with its successors in such
capacity, the "Administrative Agent"). 

          WHEREAS, the parties hereto are parties to a Credit Agreement dated as
of March 20, 1991 among the Company, the Subsidiary Guarantor, the Banks, the
Co-Agents and the Administrative Agent (as at any time amended or otherwise
modified, the "Credit Agreement"; terms defined therein having their respective
defined meanings when used herein unless otherwise defined herein);

          WHEREAS, the Company has requested that the Credit Agreement be
amended, and the Banks are willing to consent to such amendment upon the terms
and conditions contained herein.

          NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

          SECTION 1.  AMENDMENTS.  The Credit Documents are hereby amended
(effective as provided in Section 3 hereof) as follows:

          A.  Section 9.07 of the Credit Agreement is amended by (i)
     relettering clauses (d), (e) and (f) thereof to be clauses (e), (f)
     and (g) respectively and (ii) inserting a new clause (d) therein
     reading as follows:

               "(d)  Indebtedness of the Company and its Subsidiaries to NL in
          an aggregate principal amount not exceeding $5,150,000 (or the
          equivalent or such amount (as of the date such Indebtedness is
          incurred) in any other currency), provided that the proceeds of such
          Indebtedness shall be used solely to make Investments permitted by
          Section 9.08(d) hereof (and it is understood and agreed that nothing
          contained in Section 9.18 hereof shall be deemed to prohibit the
          repayment of the principal of, or the payment of interest on, such
          Indebtedness);"

          B.  Each reference in the Credit Agreement and the other Credit
     Documents to the Credit Agreement shall be deemed to be a reference to the
     Credit Agreement as amended hereby.  Except as expressly provided in this
     Section 1, the Credit Agreement shall remain unchanged and in full force
     and effect.

          SECTION 2.  REPRESENTATIONS AND WARRANTIES.  Each of the Company and
the Subsidiary Guarantor represents and warrants that:

          A.  The execution and delivery of this Amendment by it has been duly
authorized by all necessary corporate action on its part.

          B.  This Amendment has been duly executed and delivered by it, and
each of this Amendment and the Credit Agreement as modified hereby constitutes
its legal, valid and binding obligation enforceable in accordance with its
respective terms subject, however, to the application by a court of general
principles of equity and to the effect of any applicable bankruptcy, insolvency,
reorganization, moratorium or similar laws affecting creditors' rights
generally.

          SECTION 3.  EFFECTIVENESS.  The provisions of Section 1 hereof shall
become effective on the date by which counterparts hereof have been duly
executed by the Company, the Subsidiary Guarantor, the Majority Banks and the
Administrative Agent and delivered to the Administrative Agent.

          SECTION 4.  COUNTERPARTS.  This Amendment may be executed in any
number of counterparts, each of which may be deemed an original but all of which
together shall constitute one and the same instrument.

          SECTION 5.  GOVERNING LAW.  This Amendment shall be governed and
construed in accordance with the laws of the State of New York.


          IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be executed by their respective officers duly authorized as of the date first
above written.

RHEOX, INC.


By                            
  Name:
  Title:

RHEOX INTERNATIONAL, INC.


By
  Name:
  Title:

THE CHASE MANHATTAN BANK
  (NATIONAL ASSOCIATION), as
   Co-Agent and
   Administrative Agent 


By
  Name:
  Title:

THE NIPPON CREDIT BANK, LTD.,
  as Co-Agent


By
  Name:
  Title:

THE CHASE MANHATTAN BANK
  (NATIONAL ASSOCIATION)


By
  Name:
  Title:

THE NIPPON CREDIT BANK, LTD.


By
  Name:
  Title:

VAN KAMPEN MERRITT PRIME
  RATE INCOME TRUST


By
  Name:
  Title:

RESTRUCTURED OBLIGATIONS BACKED
  BY SENIOR ASSETS B.V.

BY CHANCELLOR SENIOR SECURED
  MANAGEMENT, INC., its Portfolio      
Advisor:


By
  Name:
  Title:

STICHTING RESTRUCTURED OBLIGATIONS     
BACKED BY SENIOR ASSETS 2 (ROSA2)

BY CHANCELLOR SENIOR SECURED
  MANAGEMENT, INC., its Portfolio      
Advisor:


By
  Name:
  Title:

GIROCREDIT BANK,
  NEW YORK BRANCH


By
  Name:
  Title:

BANQUE PARIBAS


By
  Name:
  Title: