original.--_Photo Times._

* * * * *




A NEW METHOD OF MAKING GELATINE EMULSION.


Since gelatine emulsion first came into use one of the greatest troubles
in connection with the manufacture of it has been that of washing.
According to the first methods the time taken for this part of the
process was, I believe, about twenty-four hours. It was very much
reduced and the ease of manufacture greatly facilitated by the methods
now most generally used, and which were, I believe, first communicated
by Messrs. Wratten and Wainright. I refer to those of precipitating with
alcohol and of straining the emulsion, when set, through canvas, so
as to divide it very finely. When the latter method is resorted to a
comparatively short time is sufficient to wash it. This method, although
a great improvement upon the older ones, yet leaves much to be desired,
especially for those who are not in the habit of making emulsion
regularly, but only an occasional batch. When the weather is at all warm
it takes a long time for the emulsion to set, unless ice be used, and
when once it is set the washing process is an exceedingly "messy" one
unless the water be cooled with ice; and the amount of water taken up
during washing is often so great that there is considerable difficulty
in getting the emulsion to set on the plates. In fact, even in cold
weather, it is not an easy process to conduct in the necessary near
approach to total darkness.