The solutions for developments, both by the neutral oxalate and the
alkaline pyro processes, should be kept in air-tight glass-stoppered
bottles; in fact, rubber stoppers are superior to glass for keeping
out the air, and when they can be had should be preferred.
Glass funnels and filtering paper for filtering the various
solutions should always be kept handy for use.
Glass graduates are quite indispensable in preparing and mixing the
developing solutions.
A balance scale is equally necessary for the same purpose.
The chemical constituents of the developing outfit are:
Neutral oxalate of potash,
Protosulphate of iron, for oxalate development,
Sulphite of soda,
Sal-soda or carbonate of soda,