330 
PROFESSOR ROSCOE’S RESEARCHES ON VANADIUM. 
Silver Vanadates. 
1. Silver Orthovanadate, or Tribasic Silver Vanadate, Ag 3 Y0 4 , is precipitated as a 
deep orange-coloured powder when a freshly prepared solution of tribasic sodium salt is 
mixed with a perfectly neutral solution of silver nitrate. If the precaution of neutralizing 
the silver solution with carbonate of soda, filtering, and boiling be not adopted, a salt is 
precipitated which consists of a mixture of tribasic and tetrabasic silver salt. The colour 
of this mixed salt is lighter than that of the tribasic compound, and it gives on analysis 
a percentage of silver and vanadium intermediate between the two salts. 
Silver orthovanadate is easily soluble in nitric acid and ammonia. For analysis it was 
dissolved in nitric acid, the silver being precipitated as chloride, and the vanadium esti- 
mated in the filtrate. 
(1) 0-385 substance gave 0-369 AgCl and 0-0076 Ag, or 74-12 per cent, of silver, 
and 0*0795 V 2 0 5 , or 1T59 per cent, of vanadium. 
(2) 0-522 substance, of another preparation, gave 0-508 Ag Cl and 0-0016 Ag, or 73-54 
per cent, of silver, and 0-111 V 2 0 5 , or 11-94 per cent, of vanadium. 
Hence we have : — 
Calculated. Found. 
A gs • 
. 324-0 
73-75 
(A 
74-12 
(2) 
73-54 
Mean. 
73-83 
Y . , 
. 51-3 
11-67 
11-59 
11-94 
11-86 
0 4 . , 
. 64-0 
439-3 
14-58 
100-00 
2. Tetrabasic Silver Vanadate=A.g i Y 2 O r — This salt is prepared by precipitating a 
solution of pure tetrasodium salt with a neutral solution of silver nitrate. It is a dense 
yellow precipitate, settling very easily when the liquid is warmed, and resembling in its 
appearance ordinary tribasic phosphate of silver. 
(1) 0-4725 substance gave 0-4105 AgCl and 0-0051 Ag, or 66-45 percent, of silver, 
and 0-1345 V 2 0 5 , corresponding to 15-99 percent, vanadium. 
Hence we have : — 
Calculated. 

Found. 
A §1 ’ 
. 432-0 
66-81 
66-45 
Y, . 
. 102-6 
15-87 
15-99 
O; • 
. 112-0 
17-32 
646-6 
100-00 
From the foregoing experiments on the vanadates it appears : 
(1) That the soluble tribasic salts are less stable at the ordinary temperature than the 
tetrabasic compounds, Na 3 Y0 4 , splitting up in solution into free caustic soda and the 
pyro-salt. 
(2) That at a high temperature, on the other hand, the tribasic form is the most 
