SILVER. 673 
§ 858. Preparations of Silver used in Medicine and the Arts. 
1. Medicinal Preparations:— 
Nitrate of Silver, AgN0 3 ; Ag, 63*51 per cent. ; N 2 0 5 , 36*49 per 
cent.—This salt is either sold crystallised in colourless rhombic prisms, 
or in the form of small white pencils or sticks. It gives the reactions for 
silver and nitric acid, and stains the skin black. 100 parts, dissolved in 
distilled water, should give, with hydrochloric acid, a precipitate which, 
when washed and dried, weighs 84*3 parts. The silver is, however, far 
more quickly estimated by the blowpipe than in the wet way. One grm. 
fused in a cavity on charcoal should give a little globule of metallic 
silver, weighing about *6351 grm. The chief adulterations of this sub¬ 
stance are copper, lead, and nitrate of potash. If all the silver is pre¬ 
cipitated by hydrochloric acid, carefully filtered off, and the filtrate 
evaporated to dryness, any residue will denote adulteration or impurity. 
Argenti Oxidum, Oxide of Silver, Ag 2 0 = 232 ; Ag, 93*19 per cent. 
—A dark olive-brown powder, soluble in ammonia and nitric acid. By 
ignition it readily yields metallic silver. The B.P. directs that 29 grains 
of the oxide should yield 27 of metallic silver. 
Nitrate of Silver and Potash. —This preparation is in most of the 
pharmacopoeias—Austrian, German, Danish, Swedish, Russian, Swiss, 
and the British. A “ toughened caustic ” is made by fusing together 
potassic nitrate 5, silver nitrate 95. A mitigated caustic is made by 
fusing 1 of silver nitrate with 2, 3, 3J, and 4 parts of potassic nitrate. 
2. Silver in the Arts. —The uses of the metal in coinage, articles for 
domestic purposes, for ornament, etc., are too well known to require 
enumeration. The only forms in which silver is likely to give rise to 
accident are the salts used in medicine, photography, in the dyeing of 
hair, and in the manufacture of marking-inks. 
Hair-Dyes. —About one-half of the hair-dyes in use are made with 
nitrate of silver. The following are only a few of the recipes :— 
Aqua Orientalis. —Grain silver 2 drms., nitric acid 1 oz., steel filings 
4 drms., distilled water 1J oz.—the whole finally made up to 3J fluid 
oz., and filtered. 
Argentan Tincture. —Nitrate of silver 1 drachm, rose water 1 fluid 
oz., sufficient nitrate of copper to impart a greenish tint. 
Eau d’Afrique. —Two solutions—one of nitrate of silver, the other 
of potash, containing ammonium sulphide. 
The photographer uses various salts of silver, the chief of which are 
—the nitrate, iodide, bromide, cyanide, and chloride of silver. 
Marking-Inks. —Some of the more important recipes for marking- 
ink are as follows :— 
Nitrate of silver, 1*0 part ; hot distilled water, 3*6 parts ; mucilage, 
previously rubbed with sap-green, 1*0 part. With this is sold a 
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