um bichromate bath
by floating or by brushing. When dry, it is exposed as usual, but for a
shorter period than when the preparation contains the India ink or other
coloring matters which impede the action of light.

The progress of the impression is followed by viewing, from time to time,
the albumenized side of the paper. When the design is visible, well
defined and brownish, the proof, being removed from the printing frame, is
rubbed with very finely powdered, or, better, levigated graphite, and,
this done, immersed in cold water for from fifteen to twenty minutes, when
by gently rubbing it under a jet of water with a soft rag, or with a
sponge imbued with water, the albumen is washed off from the parts not
acted on, leaving the design on a perfectly white ground.

If instead of graphite, or any dry color insoluble in water, lithographic
ink, much thinned with turpentine oil, be applied on the print in a light
coating which permits one to see the design under it, and if, then, the
print be soaked in water and afterwards developed as just directed, an
image in greasy ink is obtained. And, furthermore, by replacing the
printing by transfer ink, one readily obtains a transfer ready for the
stone or a zinc plate to be etched in the ordinary manner.

As usual there are two causes of failures in these processes, viz., under
and over-exposures. In the former case the image is partly washed off; in
the latter the ground cannot be cleared. The reasons are obvious.

Mr. de Saint Florent gives the following processes:(26) A sheet of
albumenized or gelatinized paper is sensitized from the verso on a
solution of potassium bichromate, dried in the dark and exposed under a
positive cliche. After insolation, the proof is washed in water, to which
are added few drops of ammonia, then inked all over with an ink consisting
of 100 parts of liquid India ink, 7 parts of sulphuric acid and 3 parts of
caustic potassa, and dried in a horizontal position. When quite dry, the
proof is placed in water, and after an immersion of about ten minutes,
rubbed with a soft brush: the image little by little appears, and if the
time of exposure be right, it is soon entirely cleared, and, then, if not
enough vigorous, it may be inked again. The gloss of the image is removed
by means of a solution of caustic potassa at 10 per 100, and the proof
finally washed with care.

If in lieu of albumen paper, one employs paper prepared with a thin
coatin