834' M. Berzelius on Vcmadium. 



and a soluble subsalt is obtained, which dries by spontaneous 

 evaporation into a blue transparent varnish, which becomes 

 brown and loses water when heated to 2 1 2° Fahrenheit. The 

 water redissolves it; but the solution exposed for a long time 

 to the influence of the air becomes gi'een, and the salt is 

 eventually converted into vanadate of vanadium, which is de- 

 posited, and leaves the neutral blue salt in the state of a con- 

 centrated solution. 



Sulphate of Vanadhim and Potash. — This is obtained by 

 mixing, in proper proportions, the solutions of the two neutral 

 salts. The double salt does not crystallize, but dries into a 

 gummy mass, of a light blue colour, which contains no trace 

 of crystallization. 



Nitrate of Vatiadmrn. — Nitric acid dissolves vanadium, its 

 oxide and suboxide ; the solution has a blue colour, which is 

 not altered by boiling: but when hydrate of vanadium is dis- 

 solved to saturation in nitric acid, and the solution is suffered 

 to crystallize spontaneouslj^, it becomes green when it has ac- 

 quired a certain degree of concentration, and at the instant of 

 complete desiccation the acid decomposes and leaves vanadic 

 acid, which retains a small quantity of combined nitric acid. 



Phosphate of Vanadium. — The neutral salt gives a blue 

 syrup, which does not crystallize, and which, when dried with 

 heat, becomes white and swells like alum dried in the fire. 

 At a white heat it becomes round and agglomerates, but it 

 does not fuse. It is then of a deep colour, and completely 

 insoluble in water. The phosphate may be obtained in very 

 small blue crystals by mixing it with a certain excess of 

 phosphoric acid, and evaporating the solution at the tempera- 

 ture of 123° Fahrenheit. After some time the neutral salt is 

 found crystallized in the midst of a colourless mother-water, 

 which is merely concentrated phosphoric acid ; it may be 

 afterwards removed by alcohol. In the air these crystals ra- 

 pidly deliquesce; when a concentrated solution of phosphate of 

 vanadium is mixed with absolute alcohol, a grayish blue gela- 

 tinous precipitate is formed, which when washed with alcohol 

 and dried is almost white, and does not alter in the air. It does 

 not completely dissolve in water, and appears to be a subsalt. 



Arseniate of Vanadium. — A solution of this salt containing 

 an excess of arsenic acid gives by evaporation a crust com- 

 posed of small crystalline grains of a light blue colour, which 

 may be deprived readily of the excess of acid by washing 

 with water. It dissolves so very slowly even in hot water 

 acidulated with arsenic acid, that it might be thought inso- 

 luble; water, nevertheless, is capable of holding much of it in 

 solution. Muriatic acid dissolves the crystals readily. If arsenic 



acid 



