above disadvantage. The advantages of carbon are the absolute permanency of the pictures as regards fading, the easy manipula-tions of the process, and the fact that prints of almost any colour may be transferred to any material, and the resulting pictures can be retouched, spotted, or otherwise worked up by the brush in the same colour. The process is very easy and simple, and the materials so cheap, that every amateur should number this amongst his photographic processes. Directions have been given for double transfer only. Single transfer is easier, as the interme-diate or temporary support is not required. Reversed negatives, however, must be used, and the print is developed in precisely the same manner as directed above. When the tissue has been exposed it is transferred at once to its final support, which may be prepared with solution of gelatine as directed for double transfer or albumenised paper, the film of which has been ren-dered insoluble by immersion in a bath of two volumes of methylated alcohol, and one volume of water may be used. The transferred print is then well washed in water and soaked in the alum bath, and reared up to dry after another washing. It is stated above that "the action of light continues in the dark." Some doubt has been thrown on this, but it is an acknowledged fact that the action of light is continued, at any rate, in a damp atmosphere. The following are some of the principal mixtures used in preparing carbon tissue. The jelly is first made as follows : -
Nelson's transparent sheet gelatine ... 10 parts.
White sugar...... ...... ... 4 M
Water ... ... ... ... ... 25 ..
Soak the gelatine in the water until soft, and dissolve by the aid of a gentle heat; add the sugar, and stir thoroughly. When set, turn the jelly out, and cut off the bottom part, so as to get rid of any grit that may have settled down. A good photographic purple brown is made as follows: -
Vegetable black ... ... ... ... 72 grs.
Alizarine lake ... ... ... ... 60 ,,
Indigo............... 13 ..
Grind these with about 4 ozs. of melted jelly, using muller and slab, and add to 6 lbs. of the above-mentioned jelly.