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Storing Chemicals

acid, potassium, sodium and ammonium

CHEMICALS, STORING Chemicals need careful storing if they are to be kept good and in a proper working condition. Those given below are the chemicals mostly used in photography, and the remarks apply generally to the chemicals themselves, as bought, and not to made-up solutions, as developers, intensifiers, etc., for information as to which see under the heading " Solutions." Photo graphic chemicals may be divided into four classes—namely :— (I) Chemicals that keep well and need no special precautions, other than being stored in a dry place : Alum (ordinary and Potassium bichromate chrome) Potassium bromide Borax Potassium ferricyanide Boric acid Potassium oxalate Caramel Sodium acetate Citric acid Sodium carbonate Mercuric chloride Sodium hyposulphite (2) Chemicals that must be kept in bottles with tight-fitting corks (not glass stoppers) because of their deliquescent nature or oxidising properties :— Aduxol Magnesium powder Amidol Potassium carbonate Ammonium carbonat Potassium cyanide Ammonium sulpho- Potassium hydrate cyanide Potassium iodide Eikonogen Potassium metabisul Ferric chloride phite Ferrous sulphate Pyrogallic acid Formosulphite Sodium hydrate Glycin Sodium sulphate Hydroquinone Sodium sulphite Metol Uranium nitrate and all other dry developers not mentioned above, as metoquinone, pyro-catechin, etc.

(3) Corrosive and volatile substances, which should be kept in bottles having accurately ground glass stoppers, not corks : Acetic acid Collodion Acetone Ether Alcohol Formaline Ammonia (liquor) Hydrochloric acid Ammonium persul- Iodine phate Nitric acid Amyl acetate Sulphuric acid (4) Materials that should be kept in a dark cupboard, or in black bottles when not in use :— All kinds of liquid aniline dyes. Gold chloride in solution.

Potassium chloroplatinite in solution Silver nitrate, dry and in solution.

Chemicals that are poisonous, or otherwise dangerous, should be stored in a cupboard or some out-of-the-way place where they cannot be got at by persons unacquainted with their dan gerous properties. Such chemicals include : Acetic acid Sodium oxalate Hydrofluoric acid Chromic acid Nitric acid Hydrochloric acid Chrome alum Sulphuric acid Ammonium bichro- Ammonia mate Ammonium oxalate All soluble barium Bromine salts Formaline Soluble copper salts Lead acetate Lead nitrate Potassium oxalate Potassium bichromate Caustic soda Caustic potash Sodium bichromate Silver nitrate All developers These are in addition to the scheduled poisons, all of which must be kept in a safe place.