But if it be desired to prepare emulsion for
storage, wash the precipitate finally with alcohol, and store it either
under alcohol or dry it as usual. To use it dissolve in the manner
described above and mix with gelatine.
The great advantages of this process are evident. Not only is the
troublesome washing saved, but, what is more important, the great mass
of the gelatine is added to the emulsion in a condition which secures
to the film a hitherto unattainable firmness. Also, it enables one to
prepare a keeping emulsion with a minimum of alcohol, and, since the
quantity of gelatine in the original emulsion is so small, it dries,
when it is not desired to keep it under alcohol, so much more rapidly,
and thereby also furnishes a more constant preparation.
I am convinced that this process is as yet but in its infancy, and that
it is susceptible of great improvement. From the purely theoretical
standpoint, the property possessed by gelatine, of combining in
sufficiently cold solutions with bromide of silver in the nascent
state, and falling to the bottom in a flaky condition, is exceedingly
interesting. Evidently this property plays a part in the preparation of
emulsion which has not until now been recognized.
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