the paper for the Parisian market, I think, states that he avoids its
deterioration by keeping it wrapped in blotting paper, between two sheets
of India rubber, to exclude air and dampness. Silvered albumen and plain
paper, well desiccated, could be kept in that way for a certain period,
especially if the blotting paper is impregnated with sodium bicarbonate
and well dried.

Mr. A. Fisch advises to discard the preliminary washing and to develop
just on the removal of the proofs from the printing frame. In operating
in this manner the development is best made by floating, taking care that
the solution does not run off the back of the proof.

The developer may consist of a dilute solution of nutgalls or of

Tannin or gallic acid 4 parts
Oxalic acid 0.15 parts
Water 1,000 parts

After developing the proof should be washed rapidly--under a jet of water,
if possible--for were the iron salt and the reagent not soon removed, or
any remain in the paper, the ground would be tinted violet. And whatever
be the care taken, it very seldom occurs that the whites are pure when the
proof is dry. This for half-tone pictures has not a great importance, but
for the reproductions of plans it is sometimes objectionable. In fact it
must be acknowledged that none of the processes now at our disposal--if we
except the so-called Artigues process described further on--gives an
entirely satisfactory result. A simple and expeditious process, yielding
intense black impressions on a white ground, is yet to be found for the
reproduction of plans, maps, etc., without resorting to a negative cliche
or drawing.

THE CUPROTYPE. (BURNETT'S PROCESS.)

_This process gives positive impressions from negative cliches._

Uranic nitrate 10 parts
Cupric nitrate 2 parts
Water 100 parts

Float for a minute strong, well-sized paper on this solution and let it
dry spontaneously in the dark. Expose until the image is visible, then
develop by floating on a solution of potassium ferricyanide at 5 per 100
of water--the image appears at once with a rich brown color. When
developed, wash it in several changes of water until the unaltered salts
are eliminated. The proof is then fixed, and, if too intense, can be
reduced in water slightly acidified with hydrochloric acid. A fine black
image is obtained by toning in a solution of platinic chloride at 1 per
100 of water.

The chemical actions giving