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MCINTOS H BATTERY AND OPTICAL CO., CHICAGO, ILL., U. S. A. LANTERN SLIDES. These, probably the most beautiful and most extensively useful of all photographic productions may be produced either by copying, in a suitable camera, or by super-position. The former is the method generally adopted by those who make them commercially, or where they are to be reduced from larger negatives; the latter is almost universally employed by those who make them only for their own use. As those who possess good lanterns are generally photographers, and make negatives of a size and quality suitable for printing by super-position, and as by that method slides of the highest quality can be made with certainty and simplicity, we append the following brief synopsis of the operation : Good pictures may be made on any slow, clean-working, gelatino- bromide plate, but it is better to use the gelatino-albumen, or gela- tino-chloride, specially prepared by various makers for the purpose, either of the English standard 3^ inches square, or as is more gener- ally used in America 4^x3^. The following solutions are required, and as they will keep indefi- nitely they may be made in large quantities : No. 1.— Oxalate Solution. Sulphite of soda j oz citric acid 6 o gr ; Dissolve, and add neutral oxalate of potash 8 oz! After solution, immerse a strip of litmus paper, and if it remains blue add a solution of citric acid (100 grs. to the ounce), a few drops at a time, until alkalinity is just removed and the paper changes faintly red; then add 200 grains of citric acid and water, if needed, to make the bulk measure 40 fluid ounces, filter, and it is ready. No. 2.— Iron Solution. Sulphate of Iron Water *..!!!!.”! Dissolve , filter and add sulphuric acid No. 3.— Fixing Solution. Hyposulphite of soda Water 8 oz. 32 oz. 40 drops. 4 oz. 20 oz. No. 4.— Clearing Solution. Cyanide of potassium (pure) 60 srr Water 6o Z ; Measure off i oz. of the solution, and to the remainder add tinc- ture of iodine until a slight color remains, showing the solution to be saturated ; then add the i oz. reserved, and it will at once be cleared. Its use will be explained further on. No. 5.— Bromide Solution. Bromide of potassium The method of operation is as follows: In a room lighted only y a ruby or orange light, place the negative in the printing frame, the prepared plate on the negative just as the paper is placed in ordi- nary printing, but using several folds of canton flannel or other soft