The etching fluid is permitted to remain upon the image for half an
hour. During this time, by gently moving the finger to and fro over the
surface, the swelling or relief of the image can be distinctly felt. The
plate is not washed, but the etching fluid simply poured off, so that
the film remains impregnated with the glycerine and water; at the most,
a piece of bibulous paper is used to absorb any superfluous quantity of
the etching fluid. After etching, the plate is taken straight to the
printing press. The inking up and printing are done very much as
in lithography. If it requires a practiced hand to produce a good
lithographic print, it stands to reason that in dealing with a gelatine
printing block, instead of a stone, skill and practice are more
necessary still. Therefore at this point the photographer should hand
over the work to the lithographer, or rather the Lichtdruck printer.
It is only by coaxing judiciously, with roller and sponge, that a good
printing block can be obtained, and no amount of teaching theoretically
can beget a good printer. To appreciate how skillful a printer must be,
it is only necessary to see the imperfect proofs that first result, and
to watch how these are gradually improved by dint of rolling, rubbing,
etching, cleaning, etc. In all Lichldruck establishments, two kinds of
rollers are used, viz., of leather and glue. In some establishments,
too, they employ two kinds of ink; but Herr Loewy manages to secure
delicacy and vigor at the same time by using one ink, but rolling up
with two kinds of roller.

Collotype printing is not merely done by hand presses, but is also
done by machinery. At Herr Albert's a gas engine of six-horse power is
employed to drive the machines, and each machine requires the
attention of a skilled mechanic and a girl. The press is very like the
lithographic quick press. Upon a big steel bed lies the little collotype
block. The glass printing block, with its brownish film of gelatine,