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XVIII. Researches on Vanadium . — Part III. 
By Henry E. Roscoe, B.A . , Ph.D., F.B.S. 
Received and Read April 7, 1870. 
I. METALLIC VANADIUM. 
In the second Part of my “ Researches on Vanadium,” communicated to the Royal Society 
(Phil. Trans. 1869, p. 691), I stated that metallic vanadium absorbs hydrogen. This 
conclusion has been fully borne out by subsequent experiment ; and it appears that the 
amount of absorbed or combined hydrogen taken up by the metal varies according to 
the state of division, first, of the chloride (VC1 2 ) from which the metal is prepared, and 
secondly, and especially, of the metallic powder itself. The metal containing absorbed 
hydrogen on exposure to dry air slowly takes up oxygen, water being formed and the 
metal undergoing oxidation to a substance which resembles the metal in its appearance, 
but possesses a darker grey colour, and has a less brilliant metallic lustre than vanadium 
itself. At this point the oxidation stops, although in moist air it proceeds still further. 
Thus a portion of pure dichloride was reduced in hydrogen ; of the reduced substance, 
free from chlorine, 0-2666 grm. yielded on complete oxidation 0-4441 of V 2 0 5 , corre- 
sponding to a percentage of 93 - 6 of pure metal. On exposure to the air for some days 
this substance absorbed oxygen, losing its brilliant metallic lustre ; and when burnt in 
a current of dry oxygen, water was given off, thus : — 
(1) 0-4232 grm. gave 0-0502 grm. of water and 0-6615 grm. V 9 CL, 
(2) 0-2695 „ „ 0-0315 „ „ 0-414 „ 
or 
(1) gives 87-8 p c. vanadium; 1*3 p. c. hydrogen; 10-9 p. c. oxygen. 
(2) „ 86’7 p. c. vanadium; T3 p. c. hydrogen; 12-0 p. c. oxygen. 
The difficulty of obtaining metallic vanadium perfectly free from admixture of oxide 
was again rendered evident. Pure tetrachloride was prepared in quantity, and from this 
the dichloride was made. On heating this dichloride to whiteness for forty-eight hours 
a substance was obtained which gained on oxidation 70-7 per cent., and therefore still 
contained a slight admixture of oxide. The reducing action of sodium on the solid 
chlorides was next examined ; in this case the reduction takes place rapidly but quietly 
in an atmosphere of hydrogen at a red heat, and may be best conducted in strong iron 
tubes proved air-tight under hydraulic pressure of 200 lbs. on the square inch. Explo- 
sions occur when the tetrachloride is heated with sodium. The substance thus obtained 
by the action of sodium was found on lixivia tion to be free from chlorine, and on washing 
it was found to separate into two parts — (1) a light and finely divided black powder 
MDCCCLXX. 2 U 
