paper may be writing-paper or drawing-paper of any required texture; but to obtain the finest and sharpest detail by the artigue method, a fine paper, such as " Rives," should be used, and this should be coated with a film of plain gelatine before applying the pigmented mixture. The gelatinous mixture for use as a substratum may consist of
Hard gelatine, as Coignet's gold label ... I part. Water...... ...... ... ... 8 parts.
Soak, melt in water bath, strain through muslin into a warmed porcelain dish. The mixture must not be allowed to cool, and each sheet much be floated for an instant, and then be pinned up to dry. (See Pins.) When dry it is coated with the Indian ink mixture in the way already described. The paper thus coated is insensitive to light, and must be sensitised by being floated, face upwards, on a solution of ammonium bichromate containing I part of the salt dissolved in from 10 to 20 parts of water. If the paper is soft and porous in texture the weaker solution should be used, and floating for a few seconds may be sufficient; but if the paper is close in texture and is covered with a substratum of gelatine, the stronger sensitising liquid must be used, and the paper must remain floating on the bath for a longer period. The criterion is the penetration of the bichromate to the face of the paper, and when this is the case the pigmented film can be rubbed off by gentle friction with the finger. Should it be preferred to prepare the paper so that it shall be sensitive to light in the first instance,parts of powdered bichromate of ammonium are stirred into the mixture, as given above, immediately after the Indian ink has been added. The insensitive paper will keep indefinitely, but the sensitive paper will only keep good for a few days. W'hen the paper is dry - and it should be dried in a place which, like a kitchen, has a fire constantly burning, and the walls of which are dry - it is ex-posed under the negative until details are visible at the back. The development is an operation in which very widely different treatment may be necessary, according to atmospheric conditions and other circumstances which affect the solubility of the pig-mented film; but the instructions given for the development of the non-transfer pigment print, under Gum-Bichromate, may be taken as generally applicable. When the basis is smooth