284 On Lithography. 



upon stone is so very easy and simple, that I have thought it 

 useless to offer any specimen of it. These considerations have 

 led me to turn all my thoughts towards chalk-drawings; and it 

 appears lithography has been considered chiefly in that light, 

 both in Paris and Munich. 



The stones proper for lithography must he of a calcareous na- 

 ture, pure, hard, and of a fine grain. They must imbibe both 

 moisture and grease with equal avidity: on this is founded the 

 whole art of lithography. 



The chalk is a composition of grease, wax, shell-lac, soap and 

 black. The lithographic ink is composed of the same materials, 

 but rather softer. 



The stone must be rubbed down with fine sand to a perfect 

 level, after which it is ready to receive the drawing : when the 

 latter is executed, a weak solution of nitric acid is thrown over 

 the stone: this operation slightly corrodes its surface, and dis- 

 poses it to imbibe moisture with more facility. While the stone 

 is still wet, a cyhnder, of about three inches in diameter, and 

 covered with common printers' ink, is rolled over the whole sur- 

 face of the stone; the wet part, of course, refuses to take the ink, 

 while the chalk, being greasy, takes a portion of it from the 

 roller. The stone is now ready for printing. The press consists 

 of a box, drawn by a wheel under a wooden scraper, pressing on 

 it with great power: after the first impression the stone is wetted 

 afresh, again rolled over with the cylinder, drawn under the 

 scraper, and so on. The same process is employed for ink draw- 

 ings, except that the solution of aqua-fortis must be stronger, 

 and ths printing-ink stiflfer. 



Transfers are made either with chalk or ink, or with both to- 

 gether, on a prepared paper, which is then put damp in the 

 press, on the surface of a stone, and thrown off on it ; the stone 

 is then treated as a chalk or ink drawing. The tints of the 

 prints marked 6,7,8, 9, are produced by a second stone, covered 

 over with grease ; the lights are scraped out in the places where 

 they are intended to be; and the print being brought on the 

 stone in its exact place, produces the effect of a drawing on co- 

 loured paper touched in with white. The drawings marked 7, 

 8, 9, are printed with a third stone, to give more effect to the 

 fore-ground. 



Imitations of wood-cuts are produced by covering the stone 

 with lithographic ink, and scraping out the intended lights ; and 

 as the finer touches may be added with a hair pencil, prints far 

 superior to wood-cuts may be obtained ; but the chief advantage 

 of wood-cuts, viz. printing them at the same time with the text 

 pf the book, is lost. 



Engraving upon stone is perforrned by polishing the stone, 



and 



