20 M. Berzelius on Vanadium. 



by a strong base, such as potash or ammonia ; this how- 

 ever takes place, for an excess of either of these bases added 

 to a green salt, soon precipitates a vanadite, insoluble in the 

 alkaline litjuor, which becomes colourless. The green salts 

 appear to be uncrystallizeable ; nevertheless a solution of oxide 

 of vanadium in carbonate of ammonia exposed to the air, de- 

 posits crystals of a deep green colour, which are the green 

 vanadate of ammonia. The concentrated solutions of the 

 green salts may be evaporated to dryness, without showing 

 any appearance of oxidizement; but when they are dilute, the 

 green colour soon disappears, and the liquid becomes colour- 

 less ; that is to say, it is converted into a vanadate. 



Sulphosalts. — I have studied these salts but superficially ; 

 almost all that I can say of them is, that they exist. 



The sidphovanadates of the alkalies are soluble in water ; 

 the solutions have a fine colour, like that of porter [biere 

 anglaise]. They are obtained, either by decomposing the 

 vanadates by an hydrosulphuret, or by fusing substances which 

 contain vanadium with an alkaline carbonate and sulphur. 

 This last is a good method of extracting the last portions of 

 vanadium. The sulphovanadates are precipitated by alcohol 

 from their concentrated solutions. The precipitate, which is 

 not at all crystalline, is frequently of a very fine deep red 

 colour. The sulphovanadate of potash, dissolved in water 

 and evaporated in vacuo, does not crystallize. The residue 

 is pulverulent, brown and perfectly soluble in water. The 

 sulphovanadates of the alkaline earths are much less soluble 

 in water. They are precipitated by double decomposition, 

 when concentrated solutions are employed. The other bases 

 generally give insoluble salts. 



The sidphovanadites are remarkable for the magnificent pur- 

 ple colour of their solutions; equalling in beauty and richness 

 that of the red solutions of manganese. But to obtain them in 

 all their beauty, the presence of every other electro-positive 

 metallic oxide must be avoided, and care must be taken that 

 the hydrosulphurets from which they are prepared contain no 

 bisulphuret; for in this case, a sulphovanadate is formed at 

 the same time, the colour of which considerably diminishes 

 the beauty of that of the sulphovanadite. As far as I have 

 been able to judge from the few experiments made on these 

 salts, the sulphovanadites are to the sulphovanadates, as the 

 sulpharsenites are to the sulpharseniates. 



Hydrogen being unity, Berzelius gives 68'58as the atomic 

 weight of vanadium ; the suboxide [protoxide ?] contains one 

 atom of oxygen, the oxide [peroxide?] two atoms; and vana- 

 dic acid three atoms ol" the same principle. 



III. Re- 



