140 On the Combinations of Chromium. 



Carbonate of Chromium., is a black shining powder, so- 

 luble with effervescence in hot nitric acid. When heated to 

 redness it is decomposed, the oxide becomes ignited, and re- 

 mains of a dark green color. Obtained in the state of an hy- 

 drate, its color is light blue ; — in this state it is slightly soluble 

 in a solution of carbonic acid. It is obtained by adding 

 carbonate of ammonia, to a solution of nitrate or muriate of 

 chromium. 



Ferroprussiate of Chromium, is a light blue, insoluble 

 powder ; procured by adding ferroprussiate of potash, to mu- 

 riate of chromium. 



Borate of Chromium, is a light green insoluble powder, 

 which falls when we add borate of ammonia, to muriate of 

 chromium. Borate of ammonia, forms a precipitate in very 

 dilute solutions of chromium. 



Oxalate of Chromium, is obtained by adding oxalate of 

 ammonia, to a solution of protoxide of chromium ; it is a 

 pale green insoluble powder. In the proximate analysis of 

 vegetables, — muriate of chromium is a valuable reagent, for 

 separating the oxalic, from the tartaric, and citric acids. 



Succinate of Chromium, is a pale green powder, soluble in 

 dilute acetic acid, insoluble in water. 



Acetate of Chromium. — Oxide of chromium dissolves in 

 acetic acid and forms a salt possessing in general the char- 

 acter of the nitrate, except, that it is less readily decomposed 

 by precipitants. 



Tartrate of Chromium. — Tartaric acid dissolves moist ox- 

 ide of chromium, and forms a neutral green solution ; when 

 evaporated in a hemispherical capsule, it dries on the sides 

 like varnish ; before the water is entirely dissipated, the dry 

 portion splits into small prisms, exhibiting a pectinated ap- 

 pearance ; these prisms are usually kept in motion by the 

 vapor. When dry this salt is greenish and black ; it is de- 

 composed at a red heat. It may be employed to furnish ox- 

 ide of chromium. 



Citrate of Chromium. — Moist oxide of chromium is solu- 

 ble in citric acid, the solution when concentrated is plum 



