14, M. Berzelius on Vanadium. 



only by spontaneous evaporation. I have also observed it with 

 the salt of soda. 



Bivanadate of Potash. — This salt may be obtained by com- 

 bining the preceding with vanadic acid, either in the dry or 

 moist way; but I have preferred to prepare it in the following 

 manner : — Dissolve the vanadate, which may contain an ex- 

 cess of potash without inconvenience, and add to the solution a 

 greater quantity of acetic acid than is required to saturate half 

 the alkali; after having well stirred the mixture, it is to be 

 evaporated if too dilute, and the bivanadate is to be precipi- 

 tated by alcohol. The precipitate is to be washed with alco- 

 hol, re-dissolved in boiling water, and the solution is to be 

 slowly cooled. The salt crystallizes in large plates of a very 

 brilliant orange colour. If the crystallization be disturbed, it 

 is deposited in small yellow crystalline scales, with a lustre 

 which is almost metallic, which is retained when they are dry; 

 it is slightly soluble in cold water, but very soluble in hot 

 water, so that the greater part of the salt crystallizes on cool- 

 ing. It contains 10*42 per cent, of water of crystallization, 

 the oxygen of which is to that of the base as 3 to 1. After 

 having lost its water, it is tarnished and of a brick-red colour. 

 It is insoluble in alcohol, which precipitates it from water in 

 the state of a lemon-yellow-coloured powder. 



Vanadate of Soda. — What has been stated with respect to 

 vanadate of potash is entirely applicable to vanadate of soda. 



Bivanadate of Soda differs from bivanadate of potash, in 

 being more soluble, and crystallizes readily by spontaneous 

 evaporation. The crystals are lai-ge, transparent, and of a 

 superb orange-red colour. They effloresce in dry air, be- 

 coming yellow and opake, without losing their form. Alcohol 

 precipitates this salt completely from its solution. 



Vanadate of Lithia. — This salt is very soluble in water. 

 The solution when concentrated to the consistence of a syrup, 

 forms rounded groups of acicular crystals, diverging from a 

 common centre. 



Bivanadate of Lithia crystallizes from a syrupy solution 

 in large crystals, which perfectly resemble bichromate of pot- 

 ash. In warm dry air it loses water and becomes opake. 

 This bisalt is insoluble in concentrated alcohol ; but it dis- 

 solves in alcohol slightly diluted, so that it imperfectly preci- 

 pitates this salt from water. 



Vanadate of Ammonia. — Of all the vanadates, this deserves 

 to be best known, because it supplies the means of obtaining 

 vanadium and its oxides in a pure state*. It is prepared by 

 putting fragments of muriate of ammonia into a neutral solu- 



* Phil. Mag. and Annals, N.S., vol, x. p. 209. 



tion 



