The alcohol, both in the gelatine and silver solutions, plays a most important part: (1) It prevents decomposition of the gelatine. (2) It allows the gelatine to be precipitated with a much smaller quantity of alcohol (say about 10 ounces).
After letting the emulsion stand for a few minutes to ripen, I pour in slowly about eight ounces of alcohol, stirring all the time, and keeping the emulsion warm; the emulsion will adhere to the stirring-rod and the bottom of the vessel in a soft mass, and all that is now required is to pour away the alcohol, allow the emulsion to cool, tear it into small pieces, wash in several changes of cold water, make up the quantity to ten ounces, and strain; it is then ready for coating.
By this formula I have no difficulties whatever; my plates set in about five minutes, and their quality is such that, "unless a better method is devised," I intend to adopt it in all weathers.

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