336 M. Berzelius on Vanadium. 



Chromate of Vanadium. — Chromic acid dissolves hydrate of 

 vanadium. The solution is of a brownish yellow colour, and 

 by spontaneous evaporation leaves a brown polished varnish, 

 without any trace of crystallization. This varnish does not 

 completely redissolve in water, and the fresh solution is yel- 

 low. Sulphuretted hydrogen precipitates a greenish mass, 

 and the liquid becomes colourless. 



Oxalate of Vanadium. — Oxalic acid saturated with hydrate 

 of vanadium, and evaporated, gives a blue varnish, which is 

 transparent and dissolves slowly in cold water, but more 

 readily in warm water. This salt mixed with oxalic acid gives 

 a blue crystalline salt, which is very soluble in water. It re- 

 mains to be determined whether the first is a neutral or sub- 

 salt, and whether the second is, as it appears to be, a super- 

 salt. 



Tartrate of Vanadium. — This salt is of a light blue colour, 

 the remarkable beauty of wliich is dei'ived from its not be- 

 coming green by contact with the air. In the dry state it 

 Ibrms a transparent splintery mass, which requires many hours 

 for solution in cold water, but hot water dissolves it more 

 readily. Ammonia dissolves it; the solution has a fine purple 

 colour, which it loses by the acidification of the oxide of vana- 

 dium when it is exposed to the air. 



Oxalate of Vanadium and Potash. — This salt gives a blue 

 mass, which does not crystallize. Oxalic acid and the bin- 

 oxalates decompose vanadic acid, and form blue salts of vana- 

 dium. 



Tartrate of Vafiadium and Potash. — This salt has the ap- 

 pearance of a splintery extractive mass ; its colour is blue with 

 a strong shade of violet. It may be obtained also by dissolv- 

 ing vanadic acid by means of bitartrate of potash : in this case 

 part of the tartaric acid is decomposed. Ammonia does not 

 precipitate the double tartrate, but it imparts to it a magni- 

 ficent purple colour, which is destroyed by the action of the 

 air. 



Citrate of Vanadium. — This salt is uncrystallizable, and 

 gives a splintery mass of a very deep blue colour. It redissolves 

 slowly in cold water ; the solution is of a pure blue colour. 

 Ammonia dissolves it, and assumes a yellowish brown colour, 

 which gradually disappears by oxidation when exposed to 

 the air. 



Acetate of Vanadium. — Dilute acetic acid dissolves very 

 little hydrate of vanadium. The li(|uid is of a pale blue colour, 

 and yields a deposit when suflered to evaporate spontaneously; 

 this is a white powder, whilst the excess of acid eva))orates. 

 When evaporated in a stove it becomes green, and the resi- 

 duum 



