ree from the vapors of
iodine and bromine; for the presence of the slightest degree of either
of the above will injure the impression in no small degree. As a
preventive, let the camera be exposed to the sun or fire for a few
minutes in the morning.

Filter your mercury often, to keep the surface free from film and dust.

The hyposulphite solution should be filtered through sponge every time
it is used.

The direct rays of light must not enter the camera in conjunction with
those reflected from the object; or the picture will be veiled, and the
color of the plate changed to a thick green.

If the plate be iodized only to a light-yellow, the result might be of
a bluish or grey tinge: and this is generally the case, when the quick
is new and strong, and there is an excess of it on the plate, and yet
not enough to form the bromide iodide of silver; in which case it would
wholly spoil the impression.

Your iodine will be found to operate more successfully, when the time
required for coating the plate does not fall short of fifteen seconds,
or exceed one minute.

Too quick coating can be avoided by using less iodine in your box. In
the summer months, when the weather is 80 deg. and over, one quarter of
an ounce, or even less, will work to advantage.

ELECTROTYPING.

I am indebted to Mr. J. H. Fitzgibbons for the following process, which
he employed in producing the excellent specimens he exhibited at the
Crystal Palace:

"I shall endeavor to lay down in as comprehensive a manner as possible
the method by which I have been enabled to produce the most
satisfactory results. I use a Smee's battery (another kind will do).
After filling the cell, of common size, nearly full with water; add
about quarter of an ounce of sulphuric acid. Mix this well, and let it
stand for about three hours, or until the action of the battery becomes
weak, when it is in order to work with a very uniform action. Put one
pound of sulphate of copper in one quart of water; stir it until the
sulphate of copper is all dissolved, and then add one half ounce of
sulphuric acid and a quarter of an ounce of nitric acid. This
solution, well mixed, should be filtered, and it is ready for use. It
is very important that the solution should be kept clean, clear, and
free from all foreign substance. The above quantity of this solution
will be found sufficient for electrotyping a dozen of the sixth-size
plates. When it is required to be strength