_Proportions of Chlorides and Silver._--I trust you will allow me space in your valuable work for some remarks in reference to an important photographic query, viz. What are the proportions of chlorides and silver uniformly suited to give the best positive pictures? I am led to propose this subject for the consideration of practical photographists, and, if possible, that amateurs may arrive at something like a rule to guide them in printing positives that will please. The necessity of these remarks, to me at least, appear very evident from the wide space which stands between the proportions proposed by various operators. MR. LYTE, "N. & Q.," Vol. ix., p. 158., says 42 grains of chloride and 100 grains of silver to 1 oz. of water. MR. POLLOCK, "N. &Q.," Vol. vii., p. 588., says 20 grains chloride, and 90 grains of silver to the ounce. MR. HOCKIN has 10 grains chloride, silver 60. MR. DELAMOTTE, for albumenized paper, chloride 60 grains, silver 120. MR. THORNTHWAITE begins as low as chloride 1/2 grain, and silver 30 grains; and lastly, amidst a long range of proportions, from 1 grain of chloride to the ounce, and silver 20 grains to the ounce, DR. DIAMOND, a great authority in photography, assures all that the best results can be obtained by using of chloride 5 grains to the ounce, and of silver 40 grains to the ounce. If so, let the photographic world know that the latter proportions are sufficient, and the others needless, wasteful, and expensive without cause. I trust you agree with me in thinking that it would be of use to a large number of beginners to have the proportions best suited for printing positives defined as near as possible, and not be left to guess at proportions varying from 1/2 grain to 60 grains, and from 20 to 120. I have written hurriedly, and hope you will see the object I aim at. AMATEUR. {359}