I then pour hot water upon it, and, gently rocking the dish, you see the paper floats from the film without the necessity for pulling it with a pin, leaving the film negative on the glass. Now, the instructions say remove the remaining soluble gelatine with camel's hair brush, but, unless it requires intensifying, which no properly developed negative should require, you need not do so, but simply pour on the gelatine solution (see Eastman formula), well covering the edges of the film, and put on a level shelf to dry. I will now take up a negative in this state on the glass, but dry, and carefully cut round the edges of the film, and you see I can readily pull off the film with its gelatine support. Having now passed through the whole of the process, it behooves us to consider for a few minutes the causes of failure in the hands of beginners and their remedies: 1. The rubber will not flow over glass? Solution too thick, glass greasy. 2. Rubber peels off on drying? Dirty glass. 3. Negative not dense enough? Use more bromide and longer development. 4. Gelatine cracks on being pulled off? Add more glycerine. 5. Gelatine not thick enough? Gelatine varnish too thin, not strong enough. 6. Does not dry sufficiently hard? Too much glycerine.--_E.H. Jaques, Reported in Br. Jour. of Photography._ * * * * * HOW DIFFERENT TONES IN GELATINO-CHLORIDE PRINTS MAY BE VARIED BY DEVELOPERS. The following formulae are for use with gelatino-chloride paper or plates. The quantities are in each case calculated for one ounce, three parts of each of the following solutions being employed and added to one part of solution of protosulphate of iron. Strength, 140 grains to the ounce. _Slaty Blue._ 1.--One part of the above solution to three parts of a solution of citrate of ammonia. _Greenish Brown._ 2.--Citric acid. 180 grains Carbonate of ammonia. 50 " 3.--Citrate of ammonia. 250 grains. Chloride of sodium. 2 " 4.--Citrate of ammonia. 250 grains. Chloride of sodium. 4 " _Sepia Brown._ 5.--Citrate of ammonia. 250 grains. Chloride of sodium. 8 " _Clear Red Brown._ 6.--Citric acid. 120 grains. Carbonate of magnesia. 76 " _Warm Gray Brown._ 7.--Citric acid. 120 grains. Carbonate of soda. 205 " _Deep Red Brown._ 8.--Citric acid. 120 grains. Carbonate of potash. 117 " _Green Blue._ 9.--Citric acid. 90 grains. Carbonate of soda. 154 " Citrate of potash. 24 " Oxalate of potash. 6 "