PROFESSOR ROSCOE’S RESEARCHES ON VANADIUM. 
319 
Vanadium 
Oxybromide Silver bromide pentoxide 
taken. found. found. 
f 0-7173 0-2110 
1 '1 0-8022 1-5013 
9 f 0-9150 0-2748 
"'l 0-5580 1-038 
0 f 0-4850 0-1435 
d ‘l 0-3745 0-7085 
Percentages 
of bromine. 
of vanadium. 
16-52 
79-62 
16-87 
79-10 
16-62 
80-48 
Hence we have as the composition of the oxytribromide : 
Calculated. 
51-3 16-69 
Found. 
a . 
r 
I. 
16-52 
II. 
16-87 
\ 
III. 
16-62 
Mean. 
16-67 
240-0 78-10 
79-62 
79-10 
80-48 
79-36 
16-0 5-21 
307-3 100-00 
The colour of the oxytribromide is somewhat redder than that of bromine, and it is 
more transparent in thin films, and much more translucent than bromine. 
The oxytribromide slowly decomposes at the ordinary atmospheric temperature into 
bromine and oxydibromide ; it is very deliquescent and hydroscopic, and cannot be 
formed in presence of moisture. The specific gravity of the oxytribromide at 0° is 
2-9673, and at 14°-5 it is 2-9325. 
2. Vanadium Oxydibromide or Vanadyl Bromide , VOBr 2 , molec. wt. =227-3. — This 
substance forms suddenly when the oxytribromide is heated to temperatures above 
180°, and it is slowly produced by the same decomposition at lower temperatures. The 
oxydibromide is a yellowish-brown solid body, in appearance resembling ochre ; it is very 
deliquescent, and on heating in the air it loses all its bromine and is converted into 
the pentoxide. Thrown into water it dissolves, furnishing a blue solution of hypo-vana- 
dic (V 2 0 4 ) salt. 
The following analyses were made from oxydibromide prepared on different occasions. 
( 1 ) 
( 2 ) 
Oxydibromide 
taken. 
Vanadium 
pentoxide 
found. 
Silver 
bromide 
found. 
Percentages 
a 
t \ 
of vanadium. of bromine. 
0-7260 
0-3025 
1-2245 
23-40 71-75 
0- 5910 
1- 1259 
0-4308 
0-9738 
70-11 
21-50 
Hence we have 
Calculated. 
V . 
. 51-3 
22-57 
Br 2 . 
. 160-0 
70-39 
O . 
. 16-0 
7-04 
227-3 
100-00 
Found. 
( A 
(1). (2). Mean. 
23-40 21-50 22-45 
71-75 70-11 70-93 
2 u 2 
