370. On the Method of printing upon Stone, [Ma*, 



calcareous flag-stone which is found in England covering the 

 blue or common lias limestone. But I believe that specimens of 

 the requisite hardness and fineness of grain have not hitherto 

 been discovered in this country. The stones are first brought 

 to an even surface by rubbing them against one another, and 

 are then finished with fine sand and pumice stone. 



The ink is composed of soap, and of rosin and gum lac dis- 

 solved in a solution of caustic soda ; to which is to be added a 

 proper quantity of lamp-black : the above ingredients, after 

 being intimately mixed by trituration, are to be diluted with 

 warm distilled water to the consistence of a thick ink, which is 

 then ready for use. The same ingredients being exposed to a 

 gentle warmth, at length dry into a mass, which being put into a 

 wooden case may be used as chalk, or crayon. It is difficult to 

 find a pen which, when charged with this ink, will draw lines 

 sufficiently fine for delicate work, and, therefore, the brushes, 

 ike. of the miniature painter should be had recourse to. 



They who are accustomed to the fine handling required in pen 

 and ink drawings, will, with due care, produce the best specimens 

 of lithography. The design being drawn on the stone, either 

 with the fluid ink or with the crayon, the whole surface is to be 

 floated with water acidulated by nitrous acid in order to remove 

 any greasiness, and is then ready for use. 



Another variety in the practice of this art is to bring the sur- 

 face of the stone to a fine polish, and then to cover it with a 

 varnish of gum and lamp-black. The design is etched in by 

 cutting through the varnish by means of a needle and other 

 proper instruments, after which the prepared ink is applied with 

 a brush, and insinuates itself into the places where the varnish 

 has been cut through. The stone is then plaoed on its edge in 

 warm water, the varnish loosens and falls off, and the traces 

 filled with the prepared ink alone remain. This process has 

 been found useful for maps and other works in which very fine 

 lines are required : the varnish, however, is so much harder than 

 that in common use among engravers that some practice is 

 necessary before the- artist can employ the requisite degree of 

 force. It appears probable that by mixing treacle with the gum 

 the consistence of the varnish might be materially improved. 



The effect of wood engraving is given very perfectly by cover- 

 ing the entire surface of the stone with the prepared ink, and 

 then scratching it off in the parts intended to be white. 



The method practised by M. Engelman of taking off the 

 impressions is as follows : 



The press consists of a hollow table terminated at one end by 

 an upright frame supporting a roller, which, by means of a winch, 

 may be made to traverse along the table from one extremity to 

 the other. The stone is laid perfectly horizontally in the hollow 

 of the table, and is secured in its place by means of wedges. It 

 R then moistened with a sponge dipped in pure water till it 



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