y, even when printed under good conditions.
The blocks are shallow as compared with the zinc line process, and are
double the cost.

INTAGLIO PROCESSES.

PHOTOGRAVURE, AUTOTYPE, DALLASTYPE, ETC.

PHOTOGRAVURE.--First, a photographic negative is taken direct from the
picture to be reproduced, and from this an autotype carbon print is
taken and transferred on to glass or silvered copper, instead of on the
paper used in making carbon prints for sale. This picture is in delicate
relief, and forms the mould, upon which copper is electrically
deposited. After being made "conductive," the carbon mould is placed in
a galvanic bath, the deposit of copper upon it taking the impression
perfectly.

Another method is to transfer the same mould upon pure, clean copper,
and then operate with a powerful biting solution, which is resisted more
or less according to the varying thickness of carbon mould to be
penetrated. Thus the parts to be left smoothest are thick of carbon, and
the parts to be dark are bare, so that the mordant may act unresisted.
This, it will be perceived, is the opposite way to the process above
given, and is therefore worked from a "transparency," or photographic
"positive," instead of a negative. This is the Klick and Fox Talbot
method, and is very commonly in use at present.

The process of "photogravure" is well known, as employed by Messrs.
Boussod, Valadon, & Co. (Goupil), of Paris, and is adapted for the
reproduction of wash drawings, paintings, also drawings where the lines
are pale and uncertain, pencil, chalk, etc.; the greys and gradations of
pencil being wonderfully interpreted. In London the intaglio processes
are used by many of the firms mentioned on page 240. They are now much
used for the reproduction of photographic portraits in books, taking
place of the copperplate engraving.

THE COST of these plates is, roughly, 5/- the square inch. The makers of
these plates generally supply paper, and print, charging by the 100
copies. But engravings thus produced are comparatively little used in
modern book illustration, as they cannot be printed simultaneously with
the letter-press of a book; they are suitable only for limited editions
and "_editions de luxe_."

DRAWING MATERIALS FOR REPRODUCTION.

1.--FOR DRAWINGS IN LINE.--For general use, liquid Indian ink and
Bristol board; or hard paper of similar surface. "Clay board," the
surface of which can easily be removed with a scraper,