.

Gilding Dissolvent.--To one quart of muriatic acid add as much oxide of
iron (common iron rust) as it will dissolve in two days. This may be
done by putting in the oxide in excess. It should be frequently shook,
and when wanted for bottling it should be allowed to stand in order to
settle. When this is done the solution may be poured off, and reduced
by adding to it an equal quantity of water; then it is ready for use.
This constitutes a gilding dissolvent now in our market.

Solution for Removing Specks.--There is probably no one cause of
complaint so general as "what makes those black specks?" There are
several causes which produce them, and probably the most general are
dust, rouge, or a spray of moisture on the plate. It this be the case,
there is no solution which can remove them, as they have prevented a
chemical action with the silver, and their removal would only expose
the surface of the plate which in itself would afford a contrast with
the impression. Another and less dangerous source of these specks is
organic matter contained in the solution employed in dissolving the
chemicals, or the water in washing. Much of the hyposulphite of soda
in market contains a sulphuret, which, coming in contact with the
silver surface, immediately causes oxidation. Such spots, as well also
as most all others found on the plate after it has been exposed in the
camera, can be removed by the following, solution: To one ounce of
water add a piece of cyanide of potassium the size of a pea; filter the
solution and apply by pouring it on the surface of the plate. In all
cases the plate should first be wet with water. Apply a gentle heat,
and soon the spots disappear, leaving the impression clear and free
from all organic matter.

In the absence of cyanide of potassium, a solution of pure hyposulphite
of soda will answer as a fair substitute.

To Redeem, a Solarized Impression.--The Daguerreotype plate, prepared
in the ordinary manner, should be exposed in the camera a sufficient
time to solarize the impression. Then, before it be exposed to the
vapor of mercury, expose it for a very brief period to the vapor of
either chlorine, bromine or iodine. Then expose over mercury, as
usual. I have produced singularly interesting results by this process.

To Purify Water.--Filter the water well, and then add about three drops
of nitric acid to the pint. This can be used as absolutely pure water,
but I would recommend the