These developers are usually employed for the development of snapshot exposures, and are therefore compounded for under-exposed plates. The following are given in grains per ounce, from which any quantity may be made up by first finding the capacity of a suitable bottle and multiplying each item by the number of ounces. Use just sufficient hot water to dissolve, then fill up the bottle, shaking occasionally. No. 1: Sulphite of soda, 100 gr.; yellow prussiate of potash, 4" gr.; hydro-quinone, 25 gr.; caustic potash, 40gr.; water, 1 oz. Dissolve the potassium hydrate separately. Use 1 part with 3 parts water. Where more exposure has been given, as much as 9 parts water may be used and 10 dropg per ounce of 10-per-cent. solution of potassium bromide. No. 2: Sulphite of soda, 75 gr.; carbonate of potash, 100 gr.; glycine, 20gr.; water, 1 oz. Add glycine last. Use 1 part with 3 parts water. No. 3: Sulphite of soda, 50gr.; water, 1 oz.; amidol, 5gr. The soda should be kept as a 10-per-cent. solution, and the amidol added only when required. No. 4: Metol, 3gr.; sulphite of soda, 40gr.; hydroquinone, 4gr.; cai'bonate of potash, 20gr. Dissolve the metol first. Use 1 part with 1 part water, and, if necessary, 2 drops per ounce 10-per-cent. solution of potassium bromide.

The following formula for a single fluid developer which will not stain the fingers may be used for either plates or paper: - Dissolve 24gr. of metol in 10 oz. of distilled water, add loz. of sodium sulphite, 40 gr. of hydroquiuone, and 1/2oz. of carbonate of potash or soda. For use, take one part of developer and one part of water and add 1 drop per ounce of 10 per cent, solution of bromide of potassium. It is preferable to increase this to 4 drops per ounce for bromide paper.