Art of Printing from Stone . 
stone ; and corrodes every part of it, except where de- 
fended by the resinous ink. 
The block being washed with water, an ink similar 
to that commonly used for printing is distributed over 
it by means of printers 5 balls, a sheet of paper dis- 
posed on a frame is laid on it, and this is pressed 
down by means of a copper roller, or copper press* 
The beauty of the impression will necessarily depend 
on that of the design. These copper presses are very in- 
geniously constructed in Germany, and easily worked. 
Their weight is proportional to the method of printing 
! used. 
When the desired number of impressions is taken off, 
and the work is not intended to be used any more, the 
stone is polished anew; and thus it may be made to 
serve for thirty or forty different works. 
The sunk, or chalk method differs from that termed 
in relief only in having the stone much more corroded 
by the nitric acid. This is chiefly employed for prints, 
and has the advantage of remedying that uniformity of 
tint, which is common to prints from the chemical press. 
It is natural, that the higher parts should take less of the 
ink, and the lower parts more, so that the impression has 
less monotony ; a defect hitherto seemingly inherent in 
this mode of printing. For this method too the rollers 
must be stronger and heavier. 
As this method is more expensive, it is given up : yet 
for prints, where some degree of effect is required, and 
more clearness, it is to be preferred. In this method 
nearly pure nitric acid is employed. Indeed when the 
art was first invented, pure nitric acid was always used ; 
but soon after, to save expense, it was diluted with wa- 
ter ; and since that it has been employed more or less di- 
luted, according to the effect wished to be produced on 
the stone. 
