682 
PROFESSOR ROSCOE’S RESEARCHES ON VANADIUM. 
Hence we have for the composition of this chloride : 
Found. 
Calculated. 
7d 
(2) 
(3) 
yv 
(4) 
(5) 
(6) ^ 
Mean of 
1,2,5&6. 
= 51-3 
26-54 
27-02 
26-52 
26-36 
26-65 
26-89 
27-05 
26-87 
= 142-0 
73-46 
72-68 
73-24 
72-14 
72-73 
72-89 
73-28 
73 02 
193-3 
100-00 
99-70 
99-76 
98-50 
99-38 
99-78 
100-33 
99-89 
Vapour-density of Vanadium Tetrachloride . — Owing to the ease with which the tetra- 
chloride decomposes into the trichloride and free chlorine, a solid residue is always left 
in the bulb when the determination is made by Dumas’s method in the ordinary way, and 
the experimental number is rather too high, as the following numbers show. 
No. 1. — Weight of bulb and air at 10° C. and under 763-7 millims. . 11-1507 grms. 
Weight of bulb and vapour at 219° and under 763-7 millims. 11-5900 grms. 
Capacity of bulb 118 cub. centims., vol. of residual air 0-0 cub. centim. 
Hence the vapour-density is found to be 99-06 (H=l) or 6-86 (air=l), the calculated 
density being 96’6 (H=l) or 6-69 (air=l). 
In order to avoid the error arising from the deposition of a solid residue, an arrange- 
ment shown in fig. 1 was used. The tetrachloride was first placed in the small bulb 
(a) ; the large bulb (h) was then submerged, and the oil heated above the boiling- 
Kg. 1. 
point of the chloride. The chloride was then boiled and the vapour passed through 
the bulb ( l >), and the tube sealed at c. The bulb was then turned round in the oil so 
as to bring the point (c) below the surface, and the temperature of the bath allowed to 
rise above 200° C. ; and when the temperature had become constant, the tube was again 
sealed at d. 
No. 2. — Weight of bulb and air at 15° C. and under 751 millims. . . 19-8945 grms. 
Weight of bulb and vapour at 205° and under 758-1 millims. 20*3015 grms. 
Capacity of bulb 112 cub. centims., residual air 2 cub. centims. No solid residue was 
left in the bulb. 
Hence the vapour-density is found to be 96-6 (H=l), or 6-69 (air =1). 
No. 3. — Another determination made at a higher temperature gave a somewhat lower 
number, indicating that a portion of the tetrachloride had been decomposed. 
