coated with normal collodion. Afterward the film is cut through at the
margins of the plate by means of a sharp knife, and put into water. In a
little while--from two to five minutes--the collodion, with the image,
will be detached from the glass; the film is at once turned over in the
water, and brought out upon the glass plate. Under a soft jet of water
any air-bubbles that may exist between the collodion and the glass are
removed, and then a solution of gum arabic (two grammes of gum dissolved
in one hundred grammes of water) is poured over, and the film is allowed
to dry spontaneously.

_Exposure of the Printing Block under the Negative_.--The exposure
is very rapid. Any one conversant with photolithographic work will
understand this. At any rate, every photographer knows that bichromated
gelatine is much more rapid than the chloride of silver he generally has
to do with.

There is no other way of measuring the exposure than by the photometer
or personal experience, and the latter is by far the best.

After leaving the printing frame, the plate is immersed in cold water.
Here it remains at discretion for half an hour, or an hour; the purpose,
of course, being to wash out the soluble bichromate. It is when the
print comes out of this bath that judgment is passed upon it. An
experienced eye tells at once what it is fit for. If it is yellow, the
yellowness must be of the slightest; indeed, Herr Furkl (the manager of
Herr Loewy's Lichtdruck department) will not admit that a good plate is
yellow at all. A yellow tint means that it will take up too much ink
when the roller is passed over it. The plates of Herr Obernetter,
however, are rather more yellow than Herr Loewy's--certainly only a
tinge, but still yellow; and Herr Obernetter's work proves, at any rate,