Manufacturer and builder Volume 5, 6 tai 7, 1869
M. Carré states that as long as writing is not very old, it admits of being copied, when moistened with water only, by means of the well-known copying press; further, that when writing has once attained a certain age, an alteration takes place in the ink, which prevents the ordinary process of copying being successful but, in that case, moistening with water acidulated with hydrochloric acid effectutlly aids the copying process. When, however, the writing has attained the age of eighty years and over, this contrivance also fails to insure a copy. M. Cane found that writing made in 1787 could not be reproduced by the copying-press, even when previously moistened with acidulated water.
If these statements are well founded, the tests here described must form valuable indications of the age of legal and historical documents. We say indications, for they could hardly be received in the light of proofs, like the well-known watermarks on paper, which have often been the means of detecting legal frauds. Wills and deeds have been produced in court written on paper which, as was proved by the water-mark, had not been manufactured until years after the alleged date of the forged document. Detection by means of watermarks was the great dread of Ireland, the forger of certain plays purporting to be by Shakespeare. To avoid this, he invariably selected, sheets which had no watermarks.