At this juncture an ink invented by a Mr Parsons was favourably reported on as an obliterant, but it shortly yielded to the skill of Messrs Perkins & Co.; and the stamp-cleaning frauds continuing, several of our leading scientific men, including Faraday, were consulted. As a result, new obliterating inks, red and black, were successively produced, tested, and adopted, but only for a while. Some of the experiment-makers lived as far off as Dublin and Aberdeen; and Dr Clark, Professor of Chemistry at the University of the latter city, came forward on his own account, and showed his interest in the cause by making or suggesting a number of experiments. Many people, indeed, went to work voluntarily, for the interest taken in the matter was widespread, and letters offering suggestions poured in from many quarters. But apparently the chemically skilled among the rogues were abler than those employed by the officials, since the “infallible” recipes had an unlucky knack of turning out dismal failures. Therefore, after consultation with Faraday, it was resolved that, so soon as the stock of stamps on hand became exhausted, an aqueous ink should be used both for the stamps and for the obliteration, ordinary black printing ink being meanwhile employed for the latter process. Professor Phillips and Mr Bacon, of the firm of Perkins & Co., at the same time undertook to procure a destructive oleaginous ink to be used in the printing of the new stamp. It was hoped that thoroughly good printer's ink would be found efficacious for obliterating purposes; but ere long a chemist named Watson completely removed the obliteration. He then proposed for use an obliterative ink of his own invention, which was tried, but proved to be inconveniently successful, since it both injured the paper and effaced the writing near the stamp. Its use had therefore to be abandoned. The trouble did not slacken, for while Mr Watson was laboriously removing the black printing ink from the black pennies, and making progress so slowly that, at a like rate, the work could not have repaid any one, honest or the reverse, for the time spent upon it, Mr Ledingham, my father's clerk, who had throughout shown great enthusiasm in the cause, was cleaning stamps nine times as fast, or at the rate of one a minute—a process rapid enough to make the trick remunerative.