ss 
THE RISE AND PROGRESS OF PHOTOGRAPHY. 157 
h a peculiar roller and a thin ae ink mix od with eeu 
printing ink. This formed the transfer ready te be put upon 
stone and treated in the ordinary manner 
imonau and Toovey used gum in the following manner:—A 
paper is floated upon a solution of gum and bichromate, dried 
and exposed behind a negative ; by a “peculiar process the unal- 
tered portions of the gum are pressed into the stone, leaving the 
lines bare ; the light having acted upon these parts, has rendered 
ins 
All the rest use gelatine gum, or ees either alone or com- 
bined, and use warm water and a fine sponge to remove eae ink 
action of the acid employed in biting 3 in Gos. 
N 
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oe . 
