f Silver;" it is prepared in the following manner:
Dissolve one hundred grains of crystalized nitrate of silver in two
ounces of distilled water, to which is added two and two-third drachms
of strong acetic acid. This solution should be kept in a bottle
carefully excluded from the light. Now, make a solution of gallic acid
in cold distilled water: the quantity dissolved is very small. When
it is required to take a picture, the two liquids above described
should be mixed together in equal quantities; but as it speedily
undergoes decomposition, and will not keep good for many minutes, only
just sufficient for the time should be prepared, and that used without
delay. It is also well not to make much of the gallic acid solution,
as it will not keep for more than a few days without spoiling. A sheet
of the iodized paper should be washed over with a brush with this mixed
solution, care being taken that it be applied to the marked side. This
operation must be performed by candle light. Let the paper rest half a
minute, then dip it into one of the dishes of water, passing it beneath
the surface several times; it is now allowed to drain, and dried by
placing its marked side upwards, on the drying apparatus. It is better
not to touch the surface with bibulous paper. It is now highly
sensitive, and ready to receive the impression. In practice it is
found better and more economical not to mix the nitrate of silver and
gallic acid, but only to brush the paper with the solution of the
nitrate.

Mr. Talbot has recently proposed some modifications in his method of
preparing the calotype paper. The paper is first iodized in the usual
way; it is then washed over with a saturated solution of gallic acid in
distilled water and dried. Thus prepared he calls it the io-gallic
paper: it will remain good for a considerable time if kept in a press
or portfolio. When required for use, it is washed with a solution of
nitrate of silver (fifty grains to the ounce of distilled water), and
it is then fit for the camera.

Exposure in the Camera.--The calotype paper thus prepared possesses a
very high degree of sensibility when exposed to light, and we are thus
provided with a medium by which, with the aid of the photogenic camera,
we may effectually copy views from nature, figures, buildings, and even
take portraits from the shadows thrown on the paper by the living face.
The paper may be used somewhat damp. The best plan for fixing it