It may also be made without putting in the water with the hydrate
of lime, by merely passing the chlorine into the hydrate of lime.
This last is by some used in preparations for accelerating the operation
of taking Daguerreotypes, but when used for this purpose it is
in small quantities.

Chloride of Calcium.--To one part of water add two parts of muriatic acid,
and add pieces of common chalk until effervescence ceases; then filter
through cotton cloth and evaporate it by placing it in all earthen
or porcelain dish, over a slow fire, to the consistency of a syrup.
When cooling, large prismatic crystals of chloride of calcium are formed.
These must be quickly dried by pressing between folds of blotting paper
and kept carefully excluded from the air, as it readily attracts hydrogen.
For most daguerreotype purposes, the syrup may be at once evaporated
to dryness. This is frequently placed in the iodine coating box
for the purpose of keeping the atmosphere dry. It is so easily made
that every operator can provide himself with it in a short time,
and at little expense.

Chloride of Gold.--Is prepared by dissolving gold in aqua regia,
a composition of one part of nitric to two parts of muriatic acid.
Gold foil is the best for our purposes; coin, however, answers,
in most cases, for the daguerreotype operator, as the alloy,
being so slight is not noticed in the gilding process.
When the latter is used, it will facilitate the operation to beat
it out, forming a thin sheet, and then cutting in small strips.
Where purity is required, foil is better. The gold is placed
in three or four times its own weight of the above acids.
For this purpose, an evaporating dish is best (a common saucer
will do); a moderate heat may be applied to favor the action.