446 Mechanical Processes of Engraving. 
was employed to deposit metal on the parts not touched: 
by the drawing. Thus, an intaglio plate was obtained 
from which the same agency afterwards produced one in re- 
lief ready for the printer. This process appeared a very 
promising one, and great success was prophesied for it, but 
I have heard nothing of its more or less extensive adoption 
from that day to this. 
Many other ingenious inventions have been introduced 
to meet the undoubted want of a cheap mechanical en- 
graving process. But most of them were based on the . 
principle of eating into the metal with acids, which, how-. 
ever, successful in line or intaglio engraving, with the pro- 
longed action required for an engraving in relief, has 
always proved fatal to practical efficiency. The cause of 
this is the lateral action of the acid, which seems to have 
defied all the efforts made to prevent it by electricity, 
gilding, varnishing, or coating with other protecting sur- 
faces. A process resembling that called the chemitype 
has, I believe, been long used for certain class of work, 
and is known as Panicography. And another similar pro- 
cess of drawing on zinc, and etching with acid, was intro- 
duced somewhat successfully by M.Gillot. The processes 
of Kobel, Volkmar, Ahner, and Besley, possess excellent 
features, but time will not permit me to dwell upon them. 
M. Dulos introduced a promising process some few years 
since. It was based upon the phenomena called capillary 
attraction. If, after drawing a design with varnish upon a 
plate of silver, er silvered copper, we level it and pour 
mercury over its surface, an effect is produced similar to 
that which would be produced if the lines*were greasy and. 
the mercury were water. In this process, therefore, the 
drawing is made direct on a plate of silvered copper in 
lithographic ink, or it may be made on paper and trans- 
ferred to the plate by pressure. By the aid of galvanism, 
a deposit of iron is thrown upon the copper not covered 
by the ink. The ink is next removed witha little benzine, 
and the lines appear in silver. Mercury being poured over 
the surface, is repulsed from the iron and attracted to the 
silver, and when the surplus mercury is removed with 
soft brushes, the lines will be found in relief above the iron. 
From this a mould is obtained, and the process of electro- 
typing completes the operations. There were objections 
to this plan, excellent as it appears in theory, and these. 
led to various modifications and improvements, but the 
process never came into practical use. In February, 
