ch may be had of Mr.
Anthony, or Mr. Roach) to the camera tube, at an angle of forty-five
degrees.

If, after taking the plate from the camera, it be examined, no picture
will yet be visible, but this is brought about by the

FOURTH PROCESS.--Bringing out the Picture, or rendering it Visible.--We
now come to the use of the mercury bath, Fig. 11. To the bath a
thermometer is attached, to indicate the proper degree of beat
required, which should never be raised above 170 deg. Fahrenheit. The
plate maybe put into one of the frames (see Fig. 11,) over the mercury,
face downwards, and examined from time to time, by simply raising it
with the fingers, or a pair of plyers. This operation, as well as the
others, should take place in the dark closet.

[Illustration: Fig. 26 (hipho_26.gif)]

[Updater's note: hipho_26.gif and hipho27.gif are both captioned Figure
27.]

Sometimes, to prevent the necessity of raising the plate, an additional
cover or top is made use of. It consists of a box fitted closely to
the inner rim of the bath, and having an inclined top (a, Fig. 27.) The
top is cut through and fitted with frames for each size of plate, like
those already described, and in the back is a piece of glass (b,)
through which to view the progress of mercurialization, and an
additional piece (c,) on one side, colored yellow, to admit the light.
The outline only of the top is here given, in order to show every
portion of it at one view.

The picture, being fully developed, is now taken out and examined; it
must not, however, be exposed to too strong a light. If any glaring
defects be perceived, it is better not to proceed with it, but place it
on one side to be re-polished; if, on the contrary, it appears perfect,
you may advance to the

FIFTH OPERATION.--Fixing the Image so that the light can no longer act
upon it.--The following articles are required for this purpose:

Two or three porcelain or glass dishes, in form, something like fig. 24.

A plate support, fig. 25. Few, I believe, now make use of this,
although it is a very convenient article.

Hyposulphite of Soda,

A pair of Plyers.

In Europe, they also use a drying apparatus, Fig. 27, but this, like
the plate support, is a matter of little consequence, and may be
dispensed with. I will, however, describe it, for the benefit of those
who may wish to use it.

[Illustration: Fig. 27 (hipho_27.gif)]

[Updater's note: hipho_26.gif and hipho27.gif are both