DEVELOPMENT AFTER FIXING.
The plate is fixed in hypo. for about 10 the handle n, the whole length of film is gradually unrolled, from off the spool at c on to the roller G in compartment E, so that the solution has access to it, the film being ingeniously arranged in several layers separated by the celluloid apron or ribbon F with corrugated rubber bands at the edges. Development is continued for a given time, the solution being of a definite strength and temperature, when the de veloper is poured off and the fixing solu tion introduced. The Tyma developing trough (Fig. 216) is an excellent contriv ance on the same principle, but possessing a funnel for pouring in the different solu tions, as well as a svrihnn nnflet It. is minutes, and may then be developed with the following stock solution :— Silver nitrate 50 °Ts • := • Ammonium sulphocyanide 120 grs.
Water ••• I oz.
Dissolve the silver nitrate first, then add the sulphoeyanide. A precipitate will be
thrown down. A 20 per cent. solution of hypo. is next added, a drop at a time, until the precipitate again dissolves, taking care to add no more hypo. than is just sufficient to accomplish this. For use, take stock solution, 2 oz. ; sodium sulphite, 10 grs. ; pyro., 3 grs. ; ammonium bromide, 2 gre. ; water, oz. ; ammonia, 3 minims. At the end of two minutes, if there is no sign of development, add another minim of am monia ; and if necessary repeat thi's, until the plate begins to develop. The opera tion may be carried out, once the plate is fixed, in weak gas-light or lamp-light. The negative should have received a liberal exposure. for the results to be satisfactory. The method is not recommended.
ently dense. For ordinary work, aim at obtaining softness and detail, rather than