Camille Silvy
1862
Photographs of Defaced Writing

Magazine page
Google Books
Annual of Scientic Discovery or, Year-Book of Facts in Science and Art for 1862 edited by David A. Wells, A.M. (Boston: Gould and Lincoln, 1862), p.145.
 
Photographs of Defaced Writing. M. Silvy, of Paris, has recently reproduced photographically one of the curious old manuscripts of early literature. He states that not only is the copy more legible than the original, but certain passages which could not be deciphered on the old parchment have been actually revived; and this is particularly visible on the last page, where a note, written in German under the signature, has become both visible and legible, while there is not a trace of it left on the original. This curious circumstance is explained as follows: " During the photographic process, the brilliant and polished parts of the parchment reflect light much better than those where the ink has been deposited. However colorless it may appear, the ink has not lost its anti-photogenic qualities, opposed to the photogenic ones of the parchment; and, thanks to this opposition, black characters may be obtained on the sensitive surface, in return for much paler ones on the original."
 
LL/39279