NEWMARKET CORPORATION
                            330 SOUTH FOURTH STREET
                              POST OFFICE BOX 2189
                         RICHMOND, VIRGINIA 23218-2189

                               POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints
each of Steven M. Edmonds and M. Rudolph West, signing singly, the undersigned's
true and lawful attorney-in-fact to:

(1)  execute for and on behalf of the undersigned, in the undersigned's capacity
     as an officer and/or director of NewMarket Corporation (the "Company"),
     forms 3, 4 and 5 in accordance with Section 16(a) of the Securities
     exchange Act of 1934 and the rules thereunder;

(2)  do and perform any and all acts for and on behalf of the undersigned that
     may be necessary or desirable to complete and execute any such Form 3, 4
     or 5, complete and execute any amendment or amendments thereto, and timely
     file such form with the United States Securities and Exchange Commission
     and any stock exchange or similar authority; and

(3)  take any other action of any type whatsoever in connection with the
     foregoing that, in the opinion of such attorney-in-fact, may be of benefit
     to, in the best interest of, or legally required by, the undersigned, it
     being understood that the documents executed by such attorney-in- fact on
     behalf of the undersigned pursuant to this Power of Attorney shall be in
     such form and shall contain such terms and conditions as such
     attorney-in-fact may approve in such attorney-in-fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein
granted. The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming, any of the undersigned's responsibilities to comply with Section 16 of the Securities Exchange Act of 1934.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 or 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 18th day of January, 2005.
                                                   /s/ David A. Fiorenza
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                                                   Signature

                                                   David A. Fiorenza
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