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                                                                    EXHIBIT 2.12
 
     FIRST AMENDMENT TO STOCK PURCHASE AGREEMENT (the "Amendment"), is made and
entered into as of March 26, 1999, among GLOBAL INDUSTRIAL TECHNOLOGIES, INC., a
Delaware corporation ("Global"), A.P. GREEN INDUSTRIES, INC., a Delaware
corporation and wholly-owned subsidiary of Global (the "Seller"), and CHEMICAL
LIME COMPANY, a Nevada corporation ("Purchaser").

                                  WITNESSETH:

     WHEREAS, Global, Seller and Purchaser entered into a Stock Purchase
Agreement dated as of March 8, 1999 (the "Agreement"); and

     WHEREAS, the parties desire to amend Section 2.2(a) and Section 9.1 of the
Agreement;

     NOW, THEREFORE, in consideration of the mutual covenants and undertakings
contained herein, and subject to and on the terms and conditions set forth
herein and in the Agreement, the parties hereto agree as follows:

     1.  Amendments.

         (a)  Section 2.2(a) of the Agreement is hereby amended by deleting the
              number "25" in clause (ii) thereof and replacing such number with
              the number "27".

         (b)  Section 9.1 of the Agreement is hereby amended by deleting the
              text of clause (ii) of the first sentence of Section 9.1 and
              replacing such text with the following: "Purchaser gives written
              termination notice to Seller at or before 7:00p.m., Central
              Standard Time, on March 31, 1999, specifying in detail the reasons
              for such termination (under clause (i) above)(the "Due Diligence
              Termination Notice)."

     2.  The Agreement, as amended by this Amendment, is and shall continue to
         be in full force and effect and is hereby in all respects ratified and
         confirmed. Nothing in this Amendment shall waive or be deemed to waive
         or modify (except as expressly set forth herein) any rights or
         obligations of any of the parities under the Agreement.

     3.  This Amendment shall be governed by, and construed in accordance with,
         the laws of the State of New York without reference to the choice of
         law principles thereof.

     4.  This Amendment may be executed in one or more counterparts each of
         which shall be deemed to be an original by the parties executing such
         counterpart, but all of which shall be considered one and the same
         instrument.
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     IN WITNESS WHEREOF, this Agreement has been signed on behalf of each of the
     parties hereto as of the date first written above.

                                             GLOBAL INDUSTRIAL
                                             TECHONOLGIES, INC.


                                         By:
                                             ------------------------------
                                             Graham L Adelman
                                             President



                                         A.P. GREEN INDUSTRIES, INC.

                                         By:
                                             ------------------------------
                                             Jeanette H. Quay
                                             Vice President



                                         CHEMICAL LIME COMPANY

                                         By:
                                             ------------------------------
                                             David M. Reilly
                                             President and CEO