Distilled water 3 oz.
Bromide Ammonium 210 grains
Gelatine 50 "
Twenty minims of No. 1 solution are introduced into the whole of No.
2, and the Gelatine is left to swell.
In another glass vessel 330 grains of nitrate of silver are
dissolved in 3 ounces of distilled water; a small quantity, about
two fluid drachms, of the latter is poured into a test tube and
diluted with an equal bulk of distilled water.
The solution of the bromo-gelatine is then rendered complete by
immersing the bottle in hot water, and the dilute silver nitrate is
added all at once.
The bottle is then shaken and the remainder of the strong silver
solution added in quantities of half an ounce at a time, shaking the
bottle as before after each addition. [p041]
The emulsion is then boiled for fifty-five (55) minutes, and when
cooled down to 90 degrees F., one ounce of gelatine, which has been
previously swelled and dissolved in water so as to measure four
ounces, is added and put away in a cold place to set.
When set, squeeze through coarse canvas into cold water one half
gallon and 1/4 lb. salt; let it remain for five minutes, then wash
thoroughly.
The addition of two ounces of alcohol and enough water to make up to
twenty ounces completes the process.
In the preparation of this or any gelatine emulsion the work may be
carried on in daylight as far as the mixing of the bromide and
silver, which must be done in a dark room by the aid of a lamp or
gas light shaded by orange or ruby glass. Sufficient of this
non-actinic light may be admitted to enable the work of washing the
emulsion, and afterwards the coating of the plates, to be carried on
with ease and comfort, as the emulsion when wet is only half as
sensitive as when dry.