wax should first be formed, about two inches in height, upon a large pane of glass: on this, the prints must be laid, in a ley made either of fresh urine, or of water mixed with a little ox-gall, for the space of three or four days; at the expiration of which time the liquor must be supplied with warm water, that ought to be changed every third or fourth hour, till it is poured off perfectly clear. Should any resinous matter remain on the prints, they must be moistened with a little alkohol.
The moisture must next be drained; and the print, being again placed on the plate of glass, ought to be covered with the oxygenated muriatic-acid liquor. Another pane is then to be placed on the lower one, to prevent any dangerous consequences arising from the pernicious vapour of the acid. In the course of one or two hours, the most discoloured prints will be restored to their original beauty. Lastly, after pouring off the acids, the prints must be washed two or three times in pure water, and dried in the sun.
PRINTING, the art of taking impressions from figures or characters, on paper, linen, silk, &c.—It is divided into three distinct branches; namely, 1. From copper-plates, for pictures, which is denominated rolling-press printing. 2. From blocks, on which birds, flowers, and other representations are cut, for printing linen, cotton, or similar articles; and which is known under the name of calico-printing. 3. From moveable letters, for multiplying books, and which has received the appellation of letter-press printing.
The branch last mentioned, is undoubtedly the most curious and valuable; as to its general dissemination, may be chiefly attributed the progress of learning; the numberless discoveries and improvements in the arts and sciences, together with a variety of other valuable contrivances in domestic life, that must otherwise have been confined to the knowledge of a few individuals, if not totally lost to mankind. Hence, several cities have contended for the honour of its first introduction; but the claim is confined principally to Haarlem, in Holland (where it was invented by Laurence Coster), and to Mentz, in Germany (where Faust and Guttenberg were the first printers): to each of these it may in some measure be ascribed; the printing with separate wooden types being first practised at Haarlem in 1430; as that with metal types (which were first cut, and afterwards cast) was discovered at Mentz, in the year 1444 or 1445.
From Holland, the art of printing was introduced into England, about the middle of the 15th century: it was first carried on at Oxford; whence it has been diffused to every quarter of the island, and is now brought near to its acme of perfection.—A more minute account of the history of this valuable art, will be found in Mr. Ames's History of Printing (3 vols. 4to. 3l. 13s. 6d. 2d edit.); and in Messrs. Bowyer's and Nichols's Origin of Printing (8vo. 2d edit. 5s. boards).
In the year 1795, the Society for the Encouragement or Arts, &c. conferred a bounty of forty guineas on Mr. Ridley, for his invention of a Printing-press, on a new construction; but, as a description of its mechanism would be intelligible only to printers, the reader is re-
