PROFESSOR ROSCOE’S RESEARCHES ON VANADIUM. 
691 
black trioxide and blue tetroxide to pentoxide. The metal-powder is not magnetic, and 
it could not be pressed into a coherent form. Its specific gravity at 15° was found to be 
5*5 as a mean of three determinations. The metal is not attacked by hydrochloric acid*, 
either when hot or cold ; neither strong nor dilute sulphuric acid act on the metal in 
the cold, but when heated with the strong acid the metal slowly dissolves, giving a 
greenish-yellow solution. Hydrofluoric acid dissolves the metal slowly with evolution 
of hydrogen, and formation of a green solution, whilst nitric acid of all strengths oxidizes 
it with violence, evolving nitrous fumes and forming a blue liquid. Both hot and cold 
solutions of caustic soda are without action on the metal, but when fused with the 
hydroxide, hydrogen is evolved and a vanadate formed. 
The metallic powder obtained by reduction contains a quantity of combined or absorbed 
hydrogen, the amount of which frequently rose up to T3 per cent. The weight of 
this hydrogen must be determined by burning the metal placed in a platinum boat, in 
a glass tube through which first a stream of dry air, and afterwards of pure oxygen is 
passed. A drying-tube placed in front of the combustion-tube gives the weight of water 
formed. 
Analysis No. 1. — 0T365 grm. of substance, containing 0*0005 grm. of hydrogen, yielded 
on oxidation 0*2420 grm. of vanadium pentoxide in long clear needle-shaped crystals. 
Hence the percentage gain is 77*94, whereas that calculated from metal is 77*98. 
Analysis No. 2. — 0*2305 grm. of metal from a different preparation, containing 
0*0022 grm. of hydrogen, yielded 0*3915 "grm. V 2 0 5 . Hence the percentage gained 
was 70*8. 
Metallic vanadium burns in excess of dry chlorine, forming the tetrachloride. A por- 
tion of dark reddish-brown chloride, formed by combustion of the metal in chlorine, 
gave the following results: 0*6958 grm. chloride yielded 1*9939 grm. AgCl, and 0*3383 
grm. V 2 0 5 . Hence the chloride contained 70*8 per cent, of chlorine and 27*3 per cent, 
of vanadium; the difference between these and the theoretical numbers (73*46 and 
26*54) being explained by the fact that the metal operated upon contained a slight 
admixture of oxide. 
Heated in an atmosphere of pure nitrogen, metallic vanadium at once absorbs this gas 
and is converted into mononitride. 
Vanadium attacks all glass or porcelain in which it is heated, a compound of silicon 
and the metal being formed. This compound coats all tubes of glass or porcelain in 
which the chlorides have been heated and reduced, as a grey lustrous metallic mirror, the 
formation of which renders the tubes very brittle and liable to crack. The silicon com- 
pound is not attacked by hydrochloric, and only slightly by nitric acid, but it tarnishes 
after a time on exposure. The metal also forms an alloy with platinum. All the pla- 
tinum boats and tubes in which the reduction has been made are found after the opera- 
tion to be completely saturated with vanadium, and require to be frequently ignited in 
* Hydrochloric acid readily dissolves the trioxide. 
