The Dictionary Of Photography

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

Home | About | Photography | Contact






Ammonia                                               Ammonium Citrate
rooms is said to cause permanent irritation of the mucous membranes of the throat, nose, and eyes. The pharmaceutical chemist keeps in stock a weaker strength, known simply as liquor ammoniae (specific gravity, '959), only one-third the strength of the liq. ammon. fort. The strength of ammonia can be estimated by determining the specific gravity, and the data will be found under the heading Hydrometers and Hydrometry, in the table which gives the specific gravities of caustic alkali solutions.
Ammonia, Fuming with. See Fuming.
Ammonium Bichromate (Ger., Dichromsaures Ammoniak; Fr., Bichromate d'ammoniaque; Ital., Bici'omato d'ammoniaca). (NH4)2Cr207=252. Made by neutralising chromic acid with ammonia. It is often used in preference to the potash salt in photo-mechanical printing, and for the gum-bichromate process.
Ammonium Bromide (Ger., Bromammonium; Fr., Bromure d'ammonium; Ital., Bromuro d,a?nmonio). NH4Br = 98. Its chief use is as a Restrainer {q.v.\ but it is sometimes used in the preparation of gelatino-bromide emulsion. Solubility : 1 in E$ of cold water, 1 in 13 of alcohol.
Ammonium Carbonate (Ger., Ammoniumcarbonat, or, Kohlensaures ammoniak; Fr., Carbonate d'ammoniaque; Ital., Carbonato d'ammoniacd). The normal carbonate - which, how-ever, is very subject to change - contains (NH4)2C03. It is used occasionally for development, but is not so suitable as liquor ammoniae. Solubility: 1 in 4 of cold water, sparingly in alcohol.
Ammonium Chloride (Ger., Chlorammonium, Sahniak; Fr., Chlorure d'ammonium; Ital., Cloridrato d'ammoniacd). NH4C1 = 53-5. Synonym : Muriate of Ammonia, Hydrochlorate of Ammonia, Sal-ammoniac. It is principally used for salting albumenised paper, and for preparing chloride emulsion. Solu-bility : 1 in 3 of cold water, 1 in 55 of alcohol.
Ammonium Citrate (Ger., Am?noniumcitrat; Fr., Citrate d'am?noniaque; Ital., Citrato d'ammoniaca). NH4, H2, C6H5Or, or (NH4)2, H, C6H507. This is usually met with in the form of solution, the salt itself being so deliquescent, that it is an extremely difficult matter to keep it. It may be conveniently prepared by exactly neutralising citric acid with solution of
24