Rollable and other films are developed in precisely the same way as a plate. A strip of rollable film of six or twelve exposures may be developed at one time, provided the exposures have been nearly the same so far as quality of light at time of exposing and the length of exposure are concerned. If, however, the exposures are uncertain, it is best to cut them into their proper sections, and treat each one separately. Care must be taken to unroll the spool in the proper manner. It is held in such a position that it will unwind as shown in Fig. 40. The black covering paper, A, will be on the outside and the film, B, on the inside; as the unwinding proceeds the film will make its appearance. The two must be held and unwound together. As soon as the white sectional marks, C1, show themselves the unwound portion should be cut away, by means of scissors, and the spool further unwound until the second marks, C2, appear; this is cut off and constitutes the first exposure. This is proceeded with until the whole of the six exposures have been cut up. Each one is now treated as a plate - except that it must be first soaked in water to make it lie flat in the developing dish. If the film is to be developed in the length, the same precaution need not be exercised. The spool is merely unrolled and the film detached from the paper. Again, in this case, the film must be soaked in water, otherwise the developer may hang on the film and form markings. The length is developed by passing it backwards and forwards through the developing solution in a specially arranged dish for the purpose; that is, one having some contrivance by means of which the film is held beneath the surface of the solution as it passes to and fro. After fixing and washing the films are hung to dry by attaching them to spring clips or by pinning to corks, to which a piece of loose string or a ring is attached.

The Development Of Films /FirstStepsInPhotography 44

Fig. 40.

Machine Development

There is new apparatus arranged for the development of films in the strip, and the work may be performed in an ordinary room and not necessarily in a dark-room. The apparatus consists of a wooden cabinet fitted up inside with mechanism, by which the film is wound off its spool into a light-tight celluloid apron. When enveloped in this apron, the film is quite protected from the light, and the two are transferred to a developing cell containing the solution, in which it is allowed to remain for a specified time. The solution is removed and the fixing solution poured in.