470 
SECOND REPORT — 18 32. 
general are colourless, and acid salts of a bright orange colour. 
With acids it gives, like molybdic acid, saline combinations. A 
remarkable double salt of this character was obtained by Ber¬ 
zelius in his process for purifying the acid ; it consisted of 1 atom 
phosphoric acid, 1 atom vanadic acid, 1 atom silica, and 3 atoms 
water. One circumstance for which this acid is remarkable is, 
that its neutral salts seem capable of existing in a coloured as well 
as a colourless state. If an acid salt be saturated with caustic 
potash, in the cold it retains a yellow colour which disappears 
after some time. If the saturation be effected with caustic am¬ 
monia, the yellow colour is permanent till the solution is heated 
near to the boiling point, when it disappears. If a solution of 
chloride of barium be poured into one of a neutral vanadiate, 
the salt of barytes falls of a beautiful yellow colour, which 
slowly disappears of itself, but the precipitate becomes at once 
white if heated near to 212°. The same is true in regard to 
the artificial vanadiate of lead,—except that the colour of this 
latter salt never becomes pure white. I have observed also 
that if a drop of nitric acid be mixed with a neutral solution of 
vanadiate of ammonia, a yellow colour is immediately developed. 
This might be attributed to the formation of a small quantity 
of bivanadiate, were it not that by standing the colour disap¬ 
pears, while the acidity remains. It would appear, therefore, 
that this acid is susceptible of two isomeric molecular arrange¬ 
ments, one of which being the cause of the colour exists in the 
bisalts, the other in the neutral salts. 
Sulphur ets .—Like molybdic and tungstic acids, the vanadic 
also combines with its oxide. But it unites in different pro¬ 
portions, and the compounds are all soluble in water. The sub - 
vanadiate of the oxide gives in water a purple solution ; the 
•• ••• ••• •• 
neutral V + 2 V a beautiful dark green; the acid 4 V + V also 
a green ; and a greater excess gives compounds of various 
shades of yellow. 
The atomic weight of vanadium, according to the experiments 
of Berzelius, = 855*84, and of vanadic acid 1155*84. 
Vanadium gives also two sulphurets, V and V, corresponding 
to the oxide and acid. 
Vanadiate of lead .—It has not yet been made out in what 
state this metal exists in the ore of iron, from which it has been 
extracted in Sweden. In the mineral from Wanlock Head it is 
in combination with lead, constituting the principal electro¬ 
negative ingredient, although there are present at the same time 
chlorine, arsenic acid, and phosphoric acid. This mineral was 
found at one time in a lead mine at Wanlock Head, which has 
