A.	Nitric acid, pure	120 parts
	Silver nitrate	6 parts
	Alcohol, 95 deg	50 parts
	Water	75 parts
B.	Nitric acid, pure	5 parts
	Alcohol, 95 deg	40 parts
	Water	60 parts

GRAPHOTYPY.

This process consists in converting a cliché in half tones into one in lines, which can be directly printed on paper, or impressed, by means of an ink transfer made as explained before, on a stone, or on a zinc or copper plate for etching in relief, or in intaglio, according as the cliché is negative or positive.

A cliché on gelatine, but preferably on a collodion film, is varnished with a solution of yellow wax and bitumen in benzole and turpentine-oil:

Bitumen of Judaea	8 parts
Yellow wax	2 parts
Benzole	40 parts
Turpentine oil	60 parts (filter)

then etched as done to engrave in the aquafortis manner, the corrections being made by applying with a brush some of the above varnish on the defective parts, which are worked over when the varnish is dry.

The tools are simply needles of various thickness ground in sharp square and round points of different sizes.

When the etching is finished, the parts which should form the ground, or white parts of the design, being covered with the bitumen varnish is non-actinic, or, in other words, does not admit the light acting on the sensitive plate preparation employed to reproduce the design, except by an exposure a good deal longer than that necessary to reduce the metallic salts.