M. Berzelius on Vanadium. 831 



sweetish, like those of h'on. Tlie greater number of them are 

 soluble in water ; the caustic alkalies occasion a precipitate, 

 which is at first of a grayish white colour, and which after- 

 wards becomes of a liver brown; an excess of alkali dissolves 

 the precipitate, producing a solution of a brown colour. Am- 

 monia added in excess gives a brown precipitate, and the li- 

 quid becomes colourless. The carbonates occasion grayish- 

 white precipitates : sulphuretted hydrogen does not render 

 them turbid, but the hydrosulphurets occasion a black preci- 

 pitate, and when added in excess they redissolve it, occasion- 

 ing a fine purple colour; ferrocyanate of potash occasions a 

 lemon-yellow pi'ecipitate, which becomes green in the air. 

 Infusion of galls gives a precipitate of so deep a blue colour 

 that it appears black. 



Chloride of Vanadium. — This salt has not been obtained in an 

 anhydrous state : it can only be formed by passing the vapour 

 of chloride of vanadium over a mixture of suboxide of vana- 

 dium and charcoal heated to redness: when sulphate of vana- 

 dium, dried as much as possible, is mixed with chloride of 

 potassium and fused, the mass contains nearly the whole of 

 the vanadium. It appears that the vanadium is converted into 

 acid at the expense of the sulphuric acid. 



Chloride of vanadium (muriate?) is very easily obtained in 

 combination with water. If vanadic acid is dissolved in con- 

 centrated muriatic acid and heated, chlorine is evolved ; but 

 when it is digested with suboxide of vanadium or with vana- 

 dium, chloride is obtained free from chlorine. The same effect 

 is produced by adding to the solution a little sugar, sulphu- 

 retted hydrogen, or alcohol. The solution has a fine blue co- 

 lour. If, on the contrary, concentrated muriatic acid be poured 

 upon oxide of vanadium prepared by calcining vanadate of 

 ammonia in close vessels, a brownish black solution is obtained, 

 and a little chlorine is disengaged, owing to the decomposition 

 of a little vanadic acid. The brown liquid, saturated as per- 

 fectly as possible with oxide, suffered to evaporate spon- 

 taneously, becomes concentrated to a certain point, but is not 

 rendered dry. Diluted with water, it retains its brown colour; 

 but when evaporated with heat, it becomes gradually completely 

 blue. This change takes place inuncdiately when sulphuric 

 acid is added, even to the concentrated liquid ; and in this 

 case neither ])recipitation nor the evolution of any gas occurs. 

 It appears that the brown chloride diflers only from the blue, 

 in being in a different isomeric state, which the sul))huric acid 

 instantly changes. The blue chloride gradually concentrates, 

 and in thin layers it dries, leaving a brown varnish, which is 

 no longer perfectly soluble in water. Evaporated at a modc- 

 2 U 2 rate 



