A Manual Of Photography

THE COLLODION PROCESS. 275 filter papers, and silks and leathers for cleaning the plates, g contains a small retort stand, a porcelain capsule, and a box with scales and weights. The case, fig. 72, is divided into two compartments. One side, a, contains twelve stoppered glass bottles, with the various chemical preparations required by the operator. The other side, which can be closed by the door 5, contains a supply of photo- graphic paper, both for negative and positive pictures. Fig. 73 is the glass trough for holding the nitrate of silver solution. 73. Fig. 74 is a frame for fixing in the camera such glass as do not require to be 74. plates of exposed to the lens while still in the glass trough. Fig. 75 is a pressure frame for the preparation of positive from negative photographs. Fig. 76 is a section of this frame. Both of these frames, figs.74 and 75, are so contrived as to be suitable for plates of many different sizes. In the frame represented by fig. 74, the bars « and 5 are both moveable, to per- mit the fixing of the plate in the camera directly opposite the centre of the lens. In the frame represented by fig. 75, the bar « alone is moveable, and is fastened by screws that mow in the slits 6, 6. The whole of these boxes and frames can be conveniently packed in the camera. The box, fig. 71, is passed in by the side-door ; the well, p, and all the other cases and frames, by the door d; and the camera, thus loaded for transport, is put into a strong leather case.