EXHIBIT 5.1


                                October 13, 1998



The Board of Directors of NL Industries, Inc.
16825 Northchase Drive
Suite 1200
Houston, Texas  77060

      Re:   Registration  Statement on Form S-8  Relating to 5,000,000  Shares
            of Common  Stock of NL  Industries,  Inc.  Available  for Issuance
            under the NL Industries, Inc. 1998 Long-Term Incentive Plan

Ladies and Gentlemen:

      We have acted as counsel for NL Industries, Inc., a New Jersey corporation
(the   "Company"),   in  connection   with  the  preparation  of  the  Company's
Registration  Statement on Form S-8 (the  "Registration  Statement") to be filed
with the  Securities  and  Exchange  Commission  on October  16,  1998 under the
Securities  Act of 1933,  as amended  (the  "Securities  Act"),  relating to the
Company's  5,000,000 shares (the "Shares") of common stock, par value $0.125 per
share (the "Common Stock"), available for issuance under the NL Industries, Inc.
1998 Long-Term Incentive Plan (the "Plan").

A.    Basis of Opinions

      As the basis for the opinions  expressed in this letter,  we have examined
and considered  originals,  or copies  certified or otherwise  identified to our
satisfaction,  of such documents,  corporate records, and instruments as we have
deemed necessary or appropriate for the expression of such opinions,  including,
without limitation, the following:

      (1)   the  Restated  Certificate  of  Incorporation  and  by-laws of the
            Company, both as amended to date;

      (2)   the minutes and records of the corporate  proceedings of the Company
            with respect to the establishment of the Plan and related matters;



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      (3)   the Plan; and

      (4) the Registration Statement.

B.    Opinions

      Based upon the foregoing,  having regard for such legal  considerations as
we have deemed relevant, and subject to the comments, assumptions,  limitations,
qualifications  and  exceptions  set forth in Section  C, we are of the  opinion
that:

      (1)   the issuance of the Shares has been duly authorized; and

      (2)   the Shares,  when  issued,  will be validly  issued,  fully paid and
            nonassessable.

C.    Comments, Assumptions, Limitations, Qualifications and Exceptions

      The  opinions  expressed  in Section B above are based upon and subject to
the further comments, assumptions, limitations, qualifications and exceptions as
set forth below.

      (1)   We have  assumed,  without  investigation,  the  genuineness  of all
            signatures and the authenticity of all documents  submitted to us as
            originals,  the  conformity to authentic  originals of all documents
            submitted to us as copies and the veracity of all such documents.

      (2)   We have assumed that (a) all awards issued under the Plan ("Awards")
            will be duly  granted in  accordance  with the terms of the Plan and
            all Shares issued in connection with the Plan will be duly issued in
            accordance with the terms of the Plan and any agreements  evidencing
            Awards;  (b)  the  Company  will  maintain  an  adequate  number  of
            authorized  but unissued  shares  and/or  treasury  shares of Common
            Stock  available  for  issuance  pursuant  to the Plan;  and (c) the
            consideration  actually  received by the Company (or the increase in
            the Company's  capital on the books of the Company,  if  applicable)
            for each issued Share is equal to or exceeds the par value thereof.

      (3)   The law covered by the opinions  expressed in this letter is limited
            to the federal  law of the United  States,  the New Jersey  Business
            Corporation Act, as amended, and the law of the state of Colorado.

       (4)  Except as set forth in subsection C.5 below,  the opinions set forth
            herein are  expressed  solely for your  benefit,  and no other party
            shall be entitled to rely on our opinions  without our prior express
            written  consent.  Without our prior express written  consent,  this
            opinion  letter  may not be quoted in whole or in part or  otherwise
            referred to in any  document or report and may not be  furnished  to
            any person or entity, except as set forth in subsection C.5 below.

        (5) We  consent  to the  filing  of this  letter  as an  exhibit  to the
            Registration  Statement and to reference to our opinions included in
            or  made a part  of  the  Registration  Statement.  In  giving  this
            consent, we do not admit that we come within the category of persons
            whose consent is required  under Section 7 of the  Securities Act or
            the rules and regulations promulgated thereunder.


                                       Respectfully submitted,




                                       /s/  Bartlit  Beck  Herman  Palenchar &
                                      Scott