COMMITTEES ON BEHALF OF THE GOVERNMENT 255 
of Engraving and Printing which completed them and delivered 
them to the office of the Commissioner of Internal Revenue to 
be issued. 
In order to ascertain whether these changes were likely to be 
effective, the Acting Commissioner of Internal Revenue on April 
13, 1870, sent some specimens of the stamps to the Academy 
with the request that they be examined by it, with regard to 
their sensitiveness to the action of chemicals. This request was 
contained in the following letter“ addressed to Joseph Henry, 
President of the Academy: 
“TREASURY DEPARTMENT, OFFICE OF INTERNAL REVENUE, 
“WASHINGTON, April 13, 1870. 
“Sir: In accordance with the third Section of the Act of Congress incor- 
porating the National Academy of Sciences, I have the honor to submit herewith 
specimens of proposed Internal Revenue Stamps for examination and report with 
reference to their sensitiveness to chemical agencies applied for the purpose of 
removing ink, cancellation marks, and their durability under ordinary usage. 
“ Very respectfully, 
“J. W. Douctass, 
“ Acting Commissioner. 
“ Pror. JOSEPH HENRY, 
“ President National Academy of Sciences, Washington, D. C.” 
A committee consisting of Wolcott Gibbs, Samuel W. John- 
son and John Torrey was at once appointed to consider the 
subject. The records of the Academy do not contain the report 
of the committee but we may infer that it was to the effect that 
the changes introduced would prevent fraud, as the Commis- 
sioner remarked in the following year: 
“Tt is believed that the stamps now being furnished under the contracts alluded 
to, cannot be tampered with. Especially is this thought to be the case with the 
adhesive, and tobacco, snuff, and cigar stamps printed on chameleon paper. This 
paper so effectually changes its color upon the application of chemical agents 
employed for the restoring of stamps for re-use, as to render restoration to its 
original state impossible.” ® 
“Proc. Nat. Acad. Sci., vol. 1, p. 76. 
™ Rep. Comm. Int. Rev. for 1870-71, p. xiv. 
