The Dictionary Of Photography

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

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Aluminium Sulphate                                                Amidol
hygroscopic. It is soluble in water, alcohol, and ether. It has been suggested as a toning agent for gelatino-chloride prints.
Aluminium Sulphate (Ger., Aluminiumsulfat; Fr., Sulfate d'aluminium; Ital., Solfato di aluminid). A12(S04)3, i8H20 is formed by dissolving aluminium hydroxide Al2(OH)6 in sulphuric acid. It has been suggested as a substitute for the ordinary and chrome alums, for hardening gelatino-chloride prints, and in emulsion making.
Amber (Ger., Grauer Amber, Bernstein; Fr., Ambre ; Ital., Ambra). A fossil resin from an extinct species of pine. It is used for preparing a Varnish (q.v.).
Ambrotype. An American synonym for a collodion positive. (See Alabastrine Process.)
Amidol (Ger., Fr., Ital., Amidol). C6H3OH(NH2)2 = 124. Synonym: Diamidophenol. The peculiar characteristic of this substance is that it will develop without the addition of alkali. It is a white crystalline powder readily soluble in water. The aqueous solution does not keep well, not even with sulphite, but soon loses its developing power; it is preferable therefore to keep it dry and dissolve as required. It is advisable to keep a stock solution of
To accelerate the development the strong solution of sodium sulphite may be added by degrees. Another form of developer has been proposed, which is as follows : -
Solution A.
Water ...............    20 ozs.
Potassium metabisulphite.........      2 ,,
Amidol ...............      1 ..
This solution will keep for a very long time if well corked.