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Ly 
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448 Mechanical Processes of E ngraving. 
The whole is next submitted to the action of an hydraulic 
press, and put under a pressure of about 150 tons, which 
consolidates the chalk into a hard cake, with a surface like 
polished ivory. Over this a wash of strong size is placed 
to guard against the possibility of the ink being used too 
thin, and so thickening and blurring the lines by spreading 
laterally. On this the artist makes his drawing, with the 
same care and lightness of touch, and in just the same way 
as line drawings are made on lithographic stones, with a 
brush specially prepared, and with a paint-like ink, princi- 
pally composed of glue and lamp-black, with probably a 
little glycerine. This flows readily, and the brush may be 
used with great freedom, especially if such a brush as 
lithographers commonly use is adopted, as it retains more 
ink than those which are more commonly used for grapho- 
typing. When the drawing is made, it can be engraved in 
a few minutes, by being subjected to the action of a 
machine, which presses and twirls a brush with great 
rapidity on the surface,and by working downward at right 
angles to the plate, soon removes all the chalk not pro- 
tected from its action by the artists’ lines. “The drawing is 
then in relief, and after being acted upon by a solution of 
silicate of potash, which gives it a stone-like hardness, is 
placed in the hands of the electrotypist, who produces an 
electrotype of it for the printer, just as he does from an 
ordinary wood engraving, it being well known that wood- 
cuts of value are seldom entrusted to printers, the risk 
incurred being too considerable. : 
In graphotype, all those qualities to which I referred as 
the requirements of a good mechanical] engraving process 
are secured, and it has many special features, giving it 
extraordinary value for a variety of useful purposes, pic- 
torial effects and novel applications, to which I have not 
now time to refer. In using the process, I make my draw- 
ing, trace it, transfer it to the plate by means of rouged 
paper, go over the tracing to correct and define it more 
slearly with a soft BBB pencil, touching the surface 
lightly and carefully lest I should disturb it, Then I put 
it in with the special ink, using it as thick as possible to 
prevent its spreading in the chalk, using sable brushes with 
points of different thicknesses, so as to avoid having to 
patch or thicken a line, a process which militates against 
its sharpness when engraved. Where I require flat tints 
I leave bare spaces, to be afterwards filled in with a ruling 
machine, by which lines of varying thicknesses are given 
