When finished, such a plate presents a surface which, 

 if inked, presents an absolutely black tone. For pro- 

 ducing the desired effect of outlines, and lights and 

 shadows, upon such a plate, the engraver scrapes away 

 with a point, or scraper, such portions as he wishes for 

 forming the outlines, controlling the tone by light or 

 heavy scraping as the case requires. This process is 

 of course a most tedious one, but the results obtained 

 from a good mezzotint more nearly resemble effects in 

 nature than any other form of reproducing before the 

 introduction of photography. Prints from the mezzo- 

 tint plate had to be very carefully made, and only a 

 comparatively small number could be obtained from a 

 plate, the pressure of the paper soon wearing it out. 



THE INVENTION OF LITHOGRAPHY 



The process of printing illustrations, letters, or dia- 

 grams by lithography is one in which stone is used in 

 place of wood or metal, as in the case of wood-engraving 

 and line engraving. The process of preparing the stone, 

 so that certain surfaces will print while others will not, 

 is done in several ways. In a general way, portions of 

 the stone which are to come in contact with the paper 

 are raised above the surrounding surface by treating 

 their surfaces with some substance not acted upon by an 

 acid, and then biting away the surrounding stone to the 

 desired depth. Another method of accomplishing this 

 same thing, however, is by treating the surfaces of the 

 printing portion with some substance that will absorb 

 printing-ink, while the surrounding stone is kept 



[1973 



