The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Water. H20=i8. The purity of water is a matter of im-portance in relation to many photographic operations, and the purest water which occurs in nature is rain water; but rain water collected in towns contains ammonia and organic impurities dis-solved from the atmosphere, to say nothing of the solid matters washed from the roofs of the houses. Those desiring to obtain a cheap and fairly satisfactory substitute for distilled water, can often do so by collecting rain water during the course of a heavy storm, but after both atmosphere and housetops have been well washed, and it is very easy to arrange a shifting gutter, so that the cleaner water is collected in a separate cistern. Spring water, river water, and all municipal or public supplies contain mineral and organic impurities; those most affecting photo-
Fig. 127.                                             Fig. 128.            Fig 129.
graphic work being soluble chlorides (sodium and sometimes magnesium) which give a white precipitate with silver nitrate; also lime salts which curdle soap. Distillation is the most satis-factory method of removing such impurities, and a convenient form of still for the photographer is one, the making of which is thus described in The Amateur Photographer of January 1st, 1897: - "Obtain a sheet of zinc about 24 by 15 ins., and make a hole about ^ in. in diameter in the middle of this sheet, 6 ins. from the side, as shown in fig. 127, then solder the narrow ends of your piece of zinc together so as to form a cylinder 15 ins. high and nearly 8 ins. in diameter. A short tube should be fixed in the hole to act as a kind of spout. Then out of a piece of tin or thin zinc make a funnel about 2 ins. deep such as fig. 128 (or this can be purchased if desired), and a tube 6 ins. or 8 ins. long, £ in. in diameter, or so as to fit the hole in the side; fix this on to the