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Photographic Printing (Ordinary phosphate of soda grs)

ordinary phosphate of soda, 20 grs.; distilled wa- | waving the dish meanwhile backwards and forter, 2 oz. Examine the chloride of gold, and if its solution immediately colors litmus-paper of a bright red, add to each grain a fragment of carbonate of soda about the size of a pin's head.

The solution of chloride of gold contains a grain to each fluidrachm of water, and will keep for an unlimited time without appreciable change, previously to the addition of the carbonate of soda. The toning baths, however, must not be kept ready mixed, since they gradually become colorless and eventually lose their toning properties in great measure. A useful simplification, substituting measure for weight, consists in having always on hand an aqueous solution of carbonate of soda containing 20 grs. to the oz.; or for the second formula, a solution of phosphate of soda containing 40 grs. to the oz. Half an oz. of the alkaline liquid would then in each case require a fluidrachm of the solution of chloride of gold, and a subsequent dilution with water to the full amount given in the formula.