328 
PROFESSOR ROSCOE’S RESEARCHES ON VANADIUM. 
Ba 9 
v/. 
O7 • 
Calculated. 
r 
_yV , 
Found. 
. 274-0 
56-08 
54-69 
. 102-6 
20-99 
21-50 
. 112-0 
22-93 
— 
488-6 
100-00 
Lead Vanadates. 
Three native lead vanadates are known. 
(a) Lead metavanadate, Pb(V0 3 ) 2 , occurs as Dechenite. 
(b) Lead pyrovanadate, Pb 2 V 2 0 7 , occurs as Descloizite. 
(c) Lead ortliovanadate and lead chloride, o(Pb 3 (V0 4 ) 2 )-fPb Cl 2 , occurs as vanadinite. 
1. Basic Pyrovanadate of Lead, 2(Pb 2 V 2 0 7 )+Pb O. — When a solution of the tetra- 
sodiurn vanadate is mixed with a solution of lead acetate, a pale yellow precipitate is 
thrown down, and the liquid acquires an acid reaction. 
The properties of this salt have already been described. 
For analysis the salt was dissolved in nitric acid, and (with the exception of No. 1) the 
lead precipitated by sulphuric acid. The sulphate of lead was found to be quite free 
from vanadium, and the vanadic acid contained no lead provided care had been taken to 
remove all nitric acid by evaporation, and if the liquid was mixed with alcohol before 
the lead sulphate was filtered. 
(1) From a tetrasodium salt which had been only once recrystallized, substance taken 
0-3935 grin. ; fused with bisulphate of potash, weight of Pb S0 4 = 0-4084 grm., corre- 
sponding to 70 '92 per cent, of lead. 
(2) 0-373 grm. of the same salt gave 0-0902 V 2 0 5 , or 13-55 per cent, of vanadium. 
(3) 0-365 grm. substance gave 0-3732 grm. Pb S0 4 , or 69-85 per cent, of lead and 
0-086 V 2 0 5 , or 12-98 per cent, of vanadium. 
(4) 0-5195 substance gave 0-5311 Pb S0 4 or 69*83 per cent, of lead, and 0-125 V Q 0 5 , 
or 13-52 per cent, of vanadium. 
(5) 0-681 substance gave 0-7036 Pb S0 4 or 70-57 per cent, of lead, and 0-158 V 2 0 5 , 
or 13-03 per cent, of vanadium. 
These numbers correspond to the formula 2(Pb 2 V 2 0 7 ) + PbO. 
Calculated. Found. Mean. 
rb 5 
. 1035-0 
69-92 
70-92 
69-85 
69-83 
70-57 
70-29 
V 4 
o 15 
. 205-2 
. 240-0 
1480-2 
13-86 
16-22 
100-00 
13-55 
12-98 
13-52 
13-03 
13-27 
2. Lead Ortliovanadate, Pb 3 (V0 4 ) 2 . — The tribasic vanadate of lead falls as an inso- 
luble nearly white powder when tribasic sodium salt is precipitated by lead acetate. 
0-7245 of the substance, when decomposed by nitric acid and precipitated by sulphuric 
