tendence of M. Artigue, or on home-made tissue; the instruc-tions of Mr. Duchochois on this head, and there quoted, being a useful guide.
Carbon Printing on a Coloured Base. Occasionally carbon prints are produced on a tinted or coloured base - a coloured single or double transfer paper, for example; and |remarkable effects may be produced in this way. Thus, the interior of a blacksmith's forge has been printed with a black tissue oh a bright red transfer paper. Dr. Beisalski's method of preparing a coloured single transfer paper is as follows : - Two ounces of clear gelatine are dissolved by heat in a pint of water, and when the gelatine is dissolved three fluid drachms of a 6-per-cent. solution of chrome alum are added, with constant agitation. This gelatinous basis may be allowed to set, and when required for use may be liquified by heat, then worked up in a warm mortar with the necessary pigment, and the mixture is used when so cooled as to be of the consistency of the semi-gelatinous colour wash used by house decorators. Any permanent pigment may be employed, but light tints cannot well be produced by simply reducing the amount of an intense colour, the mixing in of a white (such as zinc white) being the only course. The paper to be coated is pinned down on a board, and the half-set mixture is applied with a bound brush like the stiff or semi-gelatinous ceiling-wash of the house decorator. When dry, the coating becomes insoluble.
Coloured Base for Double Transfer. The coloured coating or film prepared as above is too insoluble to allow the paper to be used for double transfer. A rather stronger gelatinous solution (3 ozs. gelatine instead of 2 ozs.) and considerably less chrome alum solution (about 10 drops instead of 3 drachms) must be used in preparing a double transfer paper; moreover, the coating should be thicker.
"Carbon" Tissue Containing a White Pigment. A tissue is sometimes made up with a white pigment like sulphate of barium. If such a tissue is exposed under a positive trans-parency, and the print is developed upon a dark surface, or transferred to a dark surface, a picture will result in which the ordinary functions of the tissue and transfer paper are reversed. The directions given above for tissue will serve if light or white pigments are substituted, and by developing an impression on