judged the drawing will appear as dull lines on a shiny ground. After
the paper has been completely dried it is ready for the black color.
This consists of 5 parts of shellac, 100 parts of alcohol, and 15 parts
of finely-powdered vine-black. A sponge is used to distribute the color
over the paper, and the latter is then laid in a 2 to 3 per cent. bath
of sulphuric acid, where it must remain until the black color can be
easily removed by means of a stiff brush. All the lines of the drawing
will then appear in black on a white ground. These nigrographic tracings
are very fine, but they only appear in complete perfection when the
original drawings are perfectly opaque. Half-tone lines, or the marks
of a red pencil on the original, are not reproduced in the nigrographic
copy.

"Anthrakotype" is a kind of dusting-on process. It was invented by Dr.
Sobacchi, in the year 1879, and has been lately more fully described by
Captain Pizzighelli. This process--called also "Photanthrakography"--is
founded on the property of chromated gelatine which has not been acted
on by light to swell up in lukewarm water, and to become tacky, so that
in this condition it can retain powdered color which had been dusted
on it. Wherever, however, the chromated gelatine has been acted on by
light, the surface becomes horny, undergoes no change in warm water, and
loses all sign of tackiness. In this process absolute opacity in
the lines of the original drawing is by no means necessary, for it
reproduces gray, half-tone lines just as well as it does black ones.
Pencil drawings can also be copied, and in this lies one great advantage
of the process over other photo-tracing methods, for, to a certain
extent, even half-tones can be produced.

For the paper for anthrakotype an ordinary strong, well-sized paper must
be selected. This must be coated with a gelatine solution (gelatine 1,