174 METALS AND THEIE COMBINATIONS. 



A heavy, amorphous, light yellowish powder, insoluble in 

 water, and but slightly soluble in ammonium hydrate. 



Antidotes. Sodium chloride, white of egg, or milk, followed 

 by an emetic. 



Analytical reactions. 



1. Add to solution of a silver salt, hydrosulphuric acid or 

 ammonium sulphide: a black precipitate of silver sulphide is 

 produced : 



2AgNO 3 + H 2 S = 2HNO 3 + Ag 2 S. 



2. Add hydrochloric acid, or any soluble chloride : a white, 

 curdy precipitate of silver chloride is produced, which is in- 

 soluble in acids, but soluble in ammonium hydrate : 



Ag]S T O 3 + NaCl = N&NO 3 -f- AgCl. 



3. Add chromate or bichromate of potassium: a red precipitate 

 of silver chromate or bichromate is formed. 



4. Add sodium phosphate: a pale yellow precipitate of silver 

 phosphate, Ag 3 P0 4 , is formed, which is soluble in ammonia and 

 nitric acid. 



5. Alkaline hydrates precipitate dark brown silver oxide. 

 (See above.) 



6. Potassium iodide or bromide gives a pale yellow precipitate. 

 (See above.) 



Mercury, Hydrargyrum, Hg = 199.7 (Quicksilver). Mercury is 

 sometimes found in small globules in the metallic state, but 

 generally as mercuric sulphide or cinnabar, a dark red mineral. 

 The chief supply was formerly obtained from Spain and Austria; 

 lately, however, large quantities have been obtained from Cali- 

 fornia; it is also imported from Peru and Japan. 



Mercury is obtained from cinnabar either by roasting it, or by 

 heating it with lime, which combines with the sulphur, while 

 the metal volatilizes, and is condensed by passing the vapors 

 through suitable coolers. 



Mercury is the only metal showing the liquid state at the 

 ordinary temperature; it solidifies at 40, and boils at 350, 



