4. When stones of proper size and texture cannot be conveniently obtained, slabs are sometimes constructed of lime and sand, and united with the caseous part of milk. The first part of the process which may be considered as belonging peculiarly to the art, consists in making the drawing on the stone. This is done either in ink, with steel pens and camel's hair pencils, or with crayons made of lithographic chalk. The process of drawing on stone differs but little from that on paper, with similar means. 5. For lithographic ink, a great number of receipts have been given; but the most approved composition consists of equal parts of wax, tallow, shell-lac, and common soap, with a small proportion of lamp-black. Lithographic chalk is usually composed of the same materials, combined in different proportions. 6. When the drawing has been finished, the lithographic printer prepares it for giving impressions, by using upon its surface a weak solution of acid and other ingredients, which corrode the surface of the stone, except where it is defended from its action by the grease of the chalk or ink. As soon as the stone has been sufficiently eaten away, the solution is removed by the application of spirits of turpentine and water. 7. The ink employed in this kind of printing, is similar in its composition to other kinds of printing ink. It is applied to the drawing by means of a small wooden cylinder covered with leather. The paper, which has been suitably dampened, is laid upon the stone, and after it has been covered, by turning down upon it a thick piece of leather stretched upon an iron frame, a crank is turned which brings the stone successively under the press. 8. An impression of the drawing having been thus communicated to the paper, the sheet is removed, and the process is repeated, until the proposed number of prints have been taken. Before each application of the ink, the whole face of the stone is moderately wet with water by means of a sponge; and although the roller passes over the whole surface of the stone, yet the ink adheres to no part of it, except to that which is covered with the drawing. 9. The number of impressions which may be taken from chalk drawings, varies according to their fineness. A fine drawing will give fifteen hundred; a coarse one, twice that number. Ink drawings and writings give considerably more than copperplates, the finest yielding six or eight thousand, and strong lines and writings many more. 10. Impressions from engravings can be multiplied indefinitely, with very little trouble, in the following manner. A print is taken in the usual way from the engraved plate, and immediately laid with its face upon water. When sufficiently wet, it is carefully applied to the face of a stone, and pressed down upon it by the application of a roller, until the ink is transferred to the stone. Impressions are then taken in the manner before described.