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.

License information: nan
MPAA: G
Go to source: http://www.gutenberg.org/files/8296/8296-h/8296-h.htm