38 



Dr. H. E. Roscoe's Researches on Vanadium. [June 17, 



employed for the preparation of large quantities of nitride, owing to the 

 violence of the action and consequent loss of material. The author, seek- 

 ing for a more economical method, found that if the ammonium meta- 

 vanadate (NH 4 Y0 3 ) be heated for a sufficiently long time at a white heat 

 in a current of dry ammonia, pure vanadium mononitride remains behind. 

 Analysis of a sample thus prepared gave 79*6 per cent, of vanadium and 

 20*2 per cent, of nitrogen, theory requiring 78*6 and 21*4 per cent, re- 

 spectively. The mononitride may likewise be directly prepared by igniting 

 vanadium trioxide (V 2 0 3 ) in a current of ammonia at a white heat in a 

 platinum tube, and also by subjecting the dichloride to the same treat- 

 ment. 



The Chlorides of Vanadium. — Three chlorides of vanadium have been 

 prepared, viz. : — 



Vanadium tetrachloride .... VC1 4 



Vanadium trichloride VC1 3 



Vanadium dichloride VC1 2 



1. Vanadium Tetrachloride VC1 4 , molec. wt. = 193'3, V.D. = 966 

 (H=l). — This chloride is formed as a dark reddish brown volatile liquid, 

 when metallic vanadium or the mononitride is burnt in excess of chlorine. 

 The first method adopted for the preparation of this chloride was to pass 

 dry chlorine over the mononitride heated to redness ; the whole of the 

 nitride volatilizes and a reddish-brown liquid comes over. In one opera- 

 tion 44 grammes of the crude tetrachloride was thus prepared ; the liquid 

 is purified by distillation first in a current of chlorine and then in a stream 

 of carbonic acid gas. On fractionatiug, the liquid was found to boil at 

 1 54° C. (corrected) under 760 mm of mercury. The second method de- 

 pends upon a fact already noticed in the preceding communication, that 

 the oxitrichloride (VO Cl 3 ), prepared, according to the directions of Berze- 

 lius, by passing dry chlorine over a mixture of the trioxide and charcoal, 

 possesses a port-wine colour instead of the canary-yellow tint of the pure 

 substance. This dark colour is due to the formation of the tetrachloride 

 of vanadium, and if the vapours of the oxitrichloride, together with excess 

 of dry chlorine, be passed several times over a column of red-hot charcoal 

 the whole of the oxygen of the oxichloride can be removed, and at last 

 perfectly pure tetrachloride, boiling constantly at 154° is obtained. This 

 reaction, it will be remembered, served first to demonstrate the existence of 

 oxygen in the oxitrichloride. In each distillation of the tetrachloride a 

 peach-blossom-coloured solid residue remained in the bulbs ; this sub- 

 stance is vanadium trichloride, and it slowly burns away in excess of chlo- 

 rine when heated, forming tetrachloride. 



The composition of the tetrachloride was established by six well-agree- 

 ing analyses, made from several different preparations. The mean re- 

 sult is : — 



