(Continued from page 51.) PATENT PAPER FOR THE PREVENTION OF PIRACY.—S. Bateson read a very important paper on the anastatic process of printing. As many of our readers know but little of this process, it will be instructive and interesting to give a shoriJ history of it. It was invented some eight or nine years ago by Mr. Randolph Appel, a native of Silesia, who went over to England. Owing to various circumstances the anastatic printing languished for several years, until tardy justice was done to its inventor at the Great Exhibition in 1851, when a prize medal was awarded him. Since that time it has been becoming more generally known. The term anastatic means raising up, or a reproducing as it were, and very significantly does the name express the result; for by it any number—thousands upon thousands—of reproductions of any printed documents may be obtained, each of which is a perfect fac-simile of the original, no matter how elaborate the engraving may bs, or how intricate the design. The print of which an anastatic copy is required is first moistened with very dilute nitric acid (one part of acid to seven of water.) and then.being placed between bibulous paper all superabundance of moisture is removed.— The acid being an aqueous solution will not have attached itself to the ink on the paper, printers' ink being ot an oily nature; and if the paper thus prepared be placed on a po-lishedsheet ofzinc and subjected to pressure, two results follow:—In the first place the printed portion will leave a set-off or impression on the zinc; and secondly, the nitric acid attached to the non-printed parts of the paper will eat away and corrode the zinc, converting the whole, in fact, into a very shallow stereotype. The original being removed (perfectly uninjured), the whole zinc plate should next be smeared with gum water, which will not stick to the printed or oily part but will attach itself to every other portion of the plate. A charge of printer's ink being now applied, this in its turn only attaches itself to the set-off obtained from the print. The final process consists in pjtmng over the plate a solution of phosphorous acid which etches or corrodes more deeply the non-printed portion of the zinc, and produces a surface to which printer's Snlc will not attach. The process is now complete, and from such a prepared zinc plate any number of impressions may be struck off. The uses to which this invention may be applied are various—copies of rare prints may be obtained without the aid of an engraver. Reproductions of books, or of works out of print, may be had without setting up the type, authors may illustrate their own works, and amateur artists may have fac-similes of pen-and ink sketches at a very inconsiderable expense. To be in accordance with the facts already mentioned, the anastatic process should only be applicable to the copying of impressions made with printer's ink; any other inks however, even the most fugitive, may be adapted to this operation, and hence, without some safeguard, the dishonest practices to which the anastatic process might be applied would be numerous. Copies of checks and banknotes may be taken so as to defy scrutiny. In point of fact, bankers have been mistaken again and again when examining notes and checks when forged by this process. To prevent forgeries by this process, a paper was invented and patented by Messrs. Glynn Appel, of London. It consists merely in impregnating or dyeing the pulp ot which the paper is made with an insoluble salt of copper. After a series of experiments, the pat-tentees preferred phosphate ot copper to any other salt; and for this purpose sulphate of copper and phosphate of soda are successively mixed with the pulp, which of course produce an insoluble salt, the phosphate of copper.— Besides this, a very small portion of a peculiar oily and non-drying soap is introduced, which affords a double protection. Should the forger attempt to submit a note or check printed on the patent paper to the anastatic process, a film of metallic copper separates between the paper and the zinc, not only preventing a set- off, but cements the paper so strongly that the paper must be destroyed— it can only be removed in small pieces.— Thus, the lorger is punished by the loss of the original, the public protected, and the banker benefitted, as it is presumed no forger would apply for the value of the note so unlawfully ased. Hitherto, elaborate engraving, beauty of design, and execution by skilful hands have been the sources of protection, and under such conditions a forger must either be a skilful engraver or ejnploy some person to engrave for him. This fact has generally led to the detection of forgery; but how justly alarmed bankers will become when they learn that any one who understands what is called chemical, that is to say, lithographic printing, may, with the aid of a zinc plate, a little nitric acid and a press, be able to produce such perfect fac similies of notes and checks as to pass the scrutiny ot the most lynx-eyed ot their clerks.r
This article was originally published with the title "British Association for the Advancement of Science"