Theoretically considered, it is proper that the last trace of silver nitrate should be removed; but those who are engaged in the daily practice of commercial work do not insist upon the strict observance of such a rule in all cases. An especial exception is permitted and advocated when dealing with prints from weak or underexposed negatives, this class being found to yield richer tones by not washing any of the free silver out. The plan of soaking prints in a solution of sodium acetate was originally recommended, in lieu of washing, by a member of this Association, Mr. A. L. Henderson, as long ago as 1861, the following being an outline of the method suggested by him: Slightly overprinted proofs were soaked in a bath composed of Sodium acetate 240 grains. Water 10 ounces. The unwashed proofs were moved about in this solution at least ten minutes, in order to convert all the free silver nitrate into acetate of silver. After slight rinsing in clean water the proofs were toned with Gold terchloride 4 grains. Sodium acetate 240 " Water 10 ounces. Among the advantages claimed was an entire absence from mealiness, a defect, you will remember, we now avoid by the adoption of ammoniacal fuming. Guide-books to the practice of printing usually recommended three rapid washings; the decomposing action thus set up by the quantity of free silver remaining in the paper materially quickens the speed of toning. To prevent a too rapid deposition of gold some printers prefer adding a small quantity of common salt to the toning bath, which turns the prints sufficiently red and acts in some respects equal to an intermediary bath. Preserved papers--containing, as they generally do, a certain proportion of free acid--are liable to give some trouble in toning, owing to the retarding action of the acid present. When this occurs, it is in a great measure overcome by the use of an intermediate bath of an alkaline character and sufficient strength to neutralize the acid. Either the carbonates of ammonia or soda are found useful for this purpose, and I cannot do better than quote the one mentioned by Mr. Frederick York, which, it will be remembered, is composed of Washing soda 1 ounce. Water 1 gallon. Prints treated in the manner described are ready for toning by the alkaline method to be dealt with later on. This brings us to the consideration of toning baths generally. The properties of toning baths vary somewhat according to the mode of preparation. The term "toning," as we understand it, implies a certain change of color brought about by chemical means, such as the deposition of a stable metal upon one that is easily affected by the atmosphere--electrolysis, in fact.