1869.] 



Dr. II. E. Roscoe's Researches on Vanadium. 



39 



Calculated. Found. 



V = 51-3 26 54 26-87 



Cl 4 = 142-0 73-46 73-02 



193-3 100-00 99-89 



Owing to the facility with which the tetrachloride splits up into trichlo- 

 ride and chlorine a solid residue was left in the vapour-density hulb, and 

 the density of the vapour (at 219°) was found by Dumas's method to be 

 99'06 (or 6*86) instead of 96*6 (or 6*69). By volatilising the liquid in a 

 small bulb, and allowing the vapours to pass into a large bulb already 

 heated above the boiling-point of the liquid this deposition of trichloride was 

 avoided, and the density was found to be 96-6 or 6*69 at 205°, and 93'3 

 or 6 48 at 215°, the last determination indicating that a partial decompo- 

 sition into VC1 3 and CI had occurred. The specific gravity of the liquid 

 tetrachloride at 0° is 1*8584 ; it does not solidify at —18°, nor does it at 

 this or any higher temperature undergo change of properties on treatment 

 with chlorine. It not only undergoes decomposition on boiling, but at the 

 ordinary atmospheric temperatures it splits up into VC1 3 and CI. Tubes in 

 which the liquid tetrachloride had been sealed up have burst by the pressure 

 of the evolved chlorine. Thrown into water, the tetrachloride is at once 

 decomposed, yielding a blue solution identical in colour with the liquid 

 obtained by the action of sulphurous or sulphydric acids on vanadic acid 

 in solution, and containing a vanadous salt, derived from the tetroxide V 2 0 4 . 

 In order to prove that a vanadous salt is formed when the tetrachloride is 

 thrown into water, the solution thus obtained was oxidized to vanadic 

 acid by a standard permanganate solution. The calculated percentage of 

 oxygen thus needed according to the formula 2YCl 4 + 0 + 4H 2 0==V 2 0 5 + 

 8HC1 is 4*14 ; the percentage of oxygen found by experiment was 4*11. 



The solution of the tetrachloride in water does not bleach ; but if the 

 vapour be led into water a liquid is obtained which bleaches litmus. Va- 

 nadium tetrachloride acts violently on dry alcohol and ether, forming deep- 

 coloured liquids. The author is engaged upon the examination of this 

 reaction. 



Bromine and vanadium tetrachloride, sealed up and heated together, do 

 not combine ; on the contrary, trichloride is deposited. Hence it is clear 

 that vanadium does not readily form a pentad compound with the chlorous 

 elements. 



2. Vanadium Trichloride. — VC1 3 = 157*8. The trichloride is a solid 

 body, crystallizing in splendid peach-blossom-coloured shining tables, 

 closely resembling in appearance the crystal of chromium sesquichloride. 

 It is non-volatile in hydrogen, and, when heated in the air, it decomposes, 

 glowing with absorption of oxygen, and forming the pentoxide. Heated 

 in hydrogen the trichloride first loses one atom of chlorine, forming the 

 dichloride (VC1 2 ), and afterwards, on exposure to a higher temperature, 

 loses all its chlorine, leaving metallic vanadium as a grey lustrous powder, 



