Exhibit 10.34


                               REVOLVING LOAN NOTE


$13,400,000                                                   February 9, 2001

      FOR VALUE  RECEIVED,  the  undersigned,  Tremont  Corporation,  a Delaware
corporation  ("Maker"),  promises  to pay,  on or  before  March  31,  2003 (the
"Maturity Date"), to the order of NL Environmental  Management Services, Inc., a
New Jersey  corporation  ("Payee") or any subsequent  holder,  at its offices at
16825  Northchase  Drive,  Suite  1200,  Houston TX 77060,  or such other  place
designated  by holder in writing,  the  principal  sum of THIRTEEN  MILLION FOUR
HUNDRED THOUSAND DOLLARS ($13,400,000), or such lesser amount as shall equal the
aggregate  principal  amount  of all  revolving  loans  made to  Maker  by Payee
hereunder (the "Revolving  Loans"),  together with interest from the date hereof
on the unpaid balance of this Note as it may exist from time to time at the rate
(herein  called  the  "Applicable  Rate") of prime plus two  percent  per annum,
determined at the beginning of each calendar quarter,  and in no event shall the
Applicable  Rate exceed the maximum  interest rate  permitted to be charged from
time to time under  applicable  law  (herein  called the  "Maximum  Rate").  The
Applicable Rate shall be determined based upon the published prime rate. Accrued
interest on the unpaid  principal of this Note shall be computed on the basis of
a 360-day  year  applied to the  actual  number of days in each  calendar  month
payable on the last business day of each calendar quarter.  Notwithstanding  the
foregoing, if at any time the Applicable Rate exceeds the Maximum Rate, the rate
of  interest  payable  under this Note shall be limited to the  Maximum  Rate as
provided above.

      Subject to the terms and  conditions  set forth in this Note,  Payee shall
make Revolving Loans to Maker at any time and from time to time from the date of
this Note until the  Maturity  Date,  in an  aggregate  principal  amount not to
exceed at any one time the Maximum  Revolving  Loan Amount (as defined below) at
such time. Revolving Loans made under this Note shall be in an integral multiple
of  $200,000  and shall be wired by Payee to the account of Maker  requested  by
Maker prior to 3:00 p.m.,  New York time, on the date  proposed by Maker.  Maker
shall give Payee irrevocable  written notice of all proposed Revolving Loans not
later than three  business  days prior to the proposed  borrowing (a  "Borrowing
Notice").  Such Borrowing Notice shall specify the aggregate principal amount of
the  Revolving  Loan that Maker is  requesting  Payee to make and the  requested
effective date of the proposed  Revolving  Loan.  Each Revolving Loan shall bear
interest  on the  outstanding  principal  balance  thereof  from the  date  such
Revolving  Loan is made at the  Applicable  Rate.  The "Maximum  Revolving  Loan
Amount" shall mean Thirteen Million Four Hundred Thousand Dollars ($13,400,000),
subject to reduction in accordance with the provisions of this Note.

      The Maximum  Revolving  Loan Amount  shall be  permanently  reduced by the
amount of $250,000 on the last day of each  calendar  quarter  beginning on June
30, 2001 (a "Reduction  Date") and any principal and accrued  interest  shall be
due and payable on each  Reduction  Date to the extent that the Revolving  Loans
then outstanding would otherwise exceed the Maximum Revolving Loan Amount. Payee
shall,  and is hereby  authorized by Maker to, endorse on the schedule  attached
hereto an appropriate  notation evidencing the date and amount of each Revolving
Loan from Payee and the

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date and amount of each payment and prepayment  with respect  thereto;  provided
that the  failure of the Payee to make such a notation on this Note or any error
in such notation shall not affect the obligations of Maker under this Note.

      Maker shall pay Payee on each  Reduction  Date, in  immediately  available
funds, a revolving loan  commitment fee (the "Fee") equal to 1/2 of 1% per annum
on the  average  unused  amount of the  Maximum  Revolving  Loan Amount for each
quarter ending on a Reduction  Date.  Such Fee shall be computed on the basis of
the  actual  number  of days  elapsed  over a year of 360  days.  Such Fee shall
commence  on the date of this Note and cease to  accrue  on the  earlier  of the
Maturity Date or any termination of Payee's commitment to make Revolving Loans.

      Maker shall have the right at any time,  in its sole  discretion  and upon
not less than 10 days written notice to Payee, to further  permanently reduce or
terminate  the Maximum  Revolving  Loan  Amount,  provided,  however,  that each
partial  reduction  thereof  shall be in an integral  multiple of $250,000.  Any
reduction of the Maximum  Revolving  Loan Amount shall be accompanied by payment
in full of any  principal  over the Maximum  Revolving  Loan Amount plus accrued
interest and accrued Fee computed as provided in the previous paragraph.

      The principal  balance of this Note may be prepaid and discharged in whole
or in part by Maker at any time and from time to time, without premium,  penalty
or fee.  Notwithstanding  the prior  sentence,  all interest that is accrued and
unpaid  with  respect to the  prepaid  principal  amount and the Fee accrued and
unpaid with respect to the unpaid Maximum Revolving Loan Amount shall be paid at
the time of the prepayment.

      The Maker,  signers,  sureties,  guarantors  and  endorsers  of this Note,
jointly and  severally,  except as otherwise  expressly set forth herein,  waive
demand, presentment,  notice of nonpayment or dishonor, diligence in collecting,
grace,  notice of any protest,  and consent to all extensions for any periods of
time and partial payments, before or after maturity.

      If this  Note is not paid at  maturity,  howsoever  such  maturity  may be
brought  about,  and  the  same  is  placed  in the  hands  of an  attorney  for
collection, or if this Note is collected by suit or through bankruptcy,  probate
or other legal  proceedings,  Maker agrees to pay holder's  costs of collection,
when incurred, including reasonable attorney's fees.

      No delay in the  payments  to  holder or in the  exercise  of any power or
right  under this  Note,  or under any  instrument  securing  payment  hereof or
executed in connection herewith,  shall operate as a waiver thereof, nor shall a
single or  partial  exercise  of any power or right  preclude  other or  further
exercise thereof or exercise of any other power or right.

      Payment  of the  indebtedness  evidenced  by this Note is  secured  by the
security  interests  established  by  the  following  documents  (the  "Security
Documents"), to wit:

            A Security  Agreement  dated as of February 9, 2001  executed by the
      Maker and Payee covering certain securities owned by Maker.


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      If at any  time  the  Payee  shall  notify  the  Maker  that a  Collateral
Deficiency (as hereinafter  defined) exits, then within 5 days of its receipt of
such notice, the Maker shall, at its option, do one of the following:

      (a) prepay principal amounts  outstanding  under this Note,  together with
          accrued and unpaid  interest on such  principal  amount to the date of
          prepayment,   so  that   immediately   following  such  prepayment  no
          Collateral Deficiency exists, or

      (b) provide  the Payee  with  additional  collateral  under  the  Security
          Documents  reasonably  acceptable  to the  Payee  so that  immediately
          following  delivery  of  such  additional   collateral  no  Collateral
          Deficiency exists.

      In the event a Collateral  Deficiency  occurs,  Payee's commitment to make
further Revolving Loans shall be terminated without notice, at the option of the
Payee, until such time as no Collateral Deficiency shall exist.

For purposes of this Note,

      (a) a  Collateral  Deficiency  exists  at any time  when  the  outstanding
          principal amount together with accrued and unpaid interest on the Note
          and the Fee exceeds 20% of the Collateral Value,

      (b) Collateral  Value  is  defined  as the  Current  Market  Value  of all
          securities pledged under the Security Documents, and

      (c) Current Market Value is defined as, with respect to any security,  the
          most  recent  closing  price of such  security  on the New York  Stock
          Exchange or any other nationally recognized securities exchange, or if
          such  security is not listed on a national  securities  exchange,  the
          closing price of such security as reported on the National Association
          of Securities Dealers Automated  Quotation System  ("NASDAQ"),  or, if
          applicable,  the average of the closing bid and ask quotation for such
          security as reported on the NASDAQ.

      The term default shall include any or all of the following:

            (a) The assignment,  voluntary or involuntary conveyance of legal or
      beneficial interest,  mortgage,  pledge or grant of a security interest in
      any of the Collateral (as defined in the Security Agreement); or

            (b) The  filing or  issuance  of a notice of any lien,  warrant  for
      distraint or notice of levy for taxes or assessment against the Collateral
      (except  for those which are being  contested  in good faith and for which
      adequate reserves have been created); or

            (c) Maker's nonpayment of any installment of principal,  interest or
      the Fee under this Note; or


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            (d) The  adjudication  of Maker as  bankrupt,  or the  taking of any
      voluntary action by Maker or any involuntary  action against Maker seeking
      an  adjudication  of Maker as  bankrupt,  or seeking  relief by or against
      Maker under any provision of the Bankruptcy Code;

            (e) Maker failing to comply with any other  covenant in this Note or
      in the Security Documents;

            (f)  Maker's  default  in any  payment  (regardless  of  amount)  of
      principal of or interest on any other indebtedness for borrowed money; or

            (g) Maker's  default in the  observance or  performance of any other
      agreement  or  condition  relating  to any  such  other  indebtedness  for
      borrowed  money or contained  in any  instrument  evidencing,  securing or
      relating  thereto or any other event shall occur or condition  exist,  the
      effect of which  default or other event or  condition  is to cause,  or to
      permit the holder of the  indebtedness to cause,  such other  indebtedness
      for borrowed money to become due prior to its stated maturity.

      An "Event of Default"  shall be deemed to have occurred  immediately  upon
any default  described in clause (d) or (g) above,  if any default  described in
clauses  (c) or (f)  above  is not  cured  within  5  days,  and if any  default
described in clauses (a),  (b), or (e) is not cured within 30 days after written
notice from Payee to Maker.

      If an  Event  of  Default  has  occurred  and is  continuing,  the  entire
principal balance and accrued interest owing hereof shall at once become due and
payable and the commitment to make Revolving  Loans shall be terminated  without
notice,  at the option of the Payee,  and the  property  covered by the Security
Documents  shall be subject to  foreclosure  under  applicable  law.  Failure to
exercise this option shall not  constitute a waiver of the right to exercise the
same in the event of any subsequent default. In the event any payment, including
interest or principal, required to be made under this Note is not made when due,
interest on the overdue sum shall accrue at a rate of prime plus four percent.

      So long as the Note shall remain  unpaid,  the Maker shall  furnish to the
Payee:

      (a) as soon as available and in any event not later than 45 days after the
          end of each of the first  three  quarters  of each  fiscal year of the
          Maker,  the  consolidated  balance sheet of the Maker as of the end of
          such quarter and the  consolidated  statements  of income and retained
          earnings and cash flows of the Maker for the period  commencing at the
          end of the previous year and ending with the end of such quarter,  all
          in  reasonable   detail  and  duly  certified  with  respect  to  such
          consolidated  statements  (subject  to  year-end  adjustments)  by  an
          officer  of the Maker as  having  been  prepared  in  accordance  with
          generally accepted accounting principles;

      (b) as soon as available and in any event not later than 90 days after the
          end of each  fiscal  year of the  Maker,  a copy of the  annual  audit
          report for such year for the  Maker,  including  therein  consolidated
          balance  sheets  of the  Maker as of the end of such  fiscal  year and
          consolidated statements of income and retained earnings

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          and of cash  flows of the Maker  for such  fiscal  year,  in each case
          certified by PricewaterhouseCoopers LLP or other independent certified
          public  accountants of recognized  standing  reasonably  acceptable to
          Payee.

      This Note shall be construed in  accordance  with the laws of the State of
New Jersey and the laws of the United States  applicable to  transactions in New
Jersey.



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      IN WITNESS WHEREOF, the undersigned Maker has executed this Note as of the
9th day of February, 2001.

                               Tremont Corporation




                                       By:  /s/ Robert E. Musgraves
                                            ------------------------------------
                                            Robert E. Musgraves

                                       Its: Vice President
                                            ------------------------------------


Acknowledged  and  agreed  to by the  undersigned  solely  with  respect  to its
obligations in the second and third paragraph of this Note:

NL Environmental Management Services, Inc.


By:  /s/ Robert D. Hardy
     -------------------------------------
     Robert D. Hardy


Its: Assistant Treasurer
     -------------------------------------



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                           SCHEDULE OF REVOLVING LOANS

Type of Transaction
(Loan or Payment)                Date                  Amount
-------------------              ----                  ------



















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