ounces or 4,800
parts

When cold mix to A.

"From the composition of the solution," says Mr. Endemann, "it is evident
that it must be strongly acid; but when this solution is exposed to light,
in the presence of the organic substances of the paper, the acidity of the
solution disappears, we obtain potassium and sodium sulphates, basic
chromium sulphate, salt and vanadic acid. While, therefore, the unchanged
parts of the paper remain acid, the changed parts acquire a neutral
reaction, and while the first will readily assimilate bases, the second
will not. Exposed in an atmosphere laden with water and aniline, the
aniline will be absorbed in those parts where the solution remains acid
and in proportion to the remaining acidity."

To develop the image the paper is spread over the opening of a frame
tightly placed on a pan, in the bottom of which is heated a solution of
aniline in water, 1:50, until the image appears brown, and for further
development in a box laden with steam water, which, according to Mr.
Endemann, requires two hours to obtain a deep black coloration. To remove
the chromium compound the picture is immersed in a solution of aqueous
ammonia, 1:6, then washed and dried.

A few years ago the aniline process was improved by developing the image
with the aniline-benzine mixture vaporized by steam in a box made
specially for that purpose, whereby a reproduction can be obtained in less
than ten minutes.

In the photographic department of Messrs Poulson & Eger's Hecia
Architectural and Ornamental Iron Works, which is directed by Charles
Bilordeaux, this process is worked in the following manner:

The developing is made of sheet iron with a door sliding up and down, it
being balanced by a counterpoise, and provided with a chimney. In the box
is a gutter, extending the whole length of the bottom, covered with muslin
and connected to a steam pipe; there is also a coil similarly connected.
After the insolation, which requires about one minute in sunshine, the
print is suspended in the box, the muslin brushed over with the solution
of aniline, and live steam allowed to pass through the gutter for only two
minutes, whereby the aniline being vaporized acts on the chromic salt and
develops the image; then the steam is allowed in the coil, and, in from
three to four minutes, the paper is dry and the picture finished. The
image stands on a slightly greenish ground, which is not objectionabl