PEOEESSOE EOSCOE’S EESEAECHES ON VANADIUM. 
683 
Weight of bulb and air 9° C. and under 762 millims. . . . 24-4722 grms. 
Weight of bulb and vapour at 215° C. and under 762 millims. 25-0102 grms. 
Capacity of bulb 169-5 cub. centims. No solid residue left in the bulb. Volume of 
mercury entering the bulb 157 cub. centims. 
Hence the vapour-density is found to be 93 - 3 (H=l) or 6-48 (air =1). 
Vanadium tetrachloride is a dark brownish-red, thickish liquid, which evolves white 
fumes when exposed to moist air. Its specific gravity was carefully determined at three 
temperatures, and found to be : 
at 0°C 1-8584 
at 8°C 1-8363 
at 32° C 1-8159. 
It does not solidify at temperatures above —18° C. ; nor does it at this, or any higher 
temperature, undergo any change of properties on treatment with chlorine. The boiling- 
point of vanadium tetrachloride is 154° C. (corrected) under a pressure of 760 millims. 
Vanadium tetrachloride not only decomposes (as has been stated) on boiling into the 
trichloride and free chlorine, but the same decomposition takes place slowly at the 
ordinary temperature of the air. The liquid tetrachloride, sealed up in glass tubes and 
exposed to the light, was found on standing for some months to be changed to a dark 
blackish powder, whilst free chlorine was liberated in such quantity as not only to 
exhibit its characteristic greenish-yellow colour, but in several cases by its pressure to 
have burst the tubes. This powder on analysis was found to consist of the trichloride 
(see analysis, p. 685) moistened with tetrachloride; on removing this latter liquid in a 
current of dry carbonic acid at 170°, the pure violet solid trichloride was left behind. 
Thrown into water the tetrachloride is at once decomposed, yielding a blue solution 
identical in colour with the liquids obtained by the action of oxalic, 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 decomposed 
by water, the quantity of oxygen which this salt absorbs in conversion into vanadic acid 
was determined with a standard permanganate solution according to the method described 
in Part I. of these researches (Phil. Trans. 1868, p. 17). 
Action of Potassium Permanganate on the aqueous solution of Vanadium Tetrachloride. 
(l) 
Weight of V Cl 4 taken 0-2375 
Cub. centim. of permanganate solution) 
required (1 cub. centim. = 0-00066 ll5-0 
grm. oxygen) J 
"Percentage gain of oxygen found . . 4-17 
(2) (3) (4) 
0-5353 0-4628 0-5687 
13-2 28-8 35-4 
4-09 4-10 4-09 
