PROFESSOR ROSCOE’S EESEAECHES ON VANADIUM. 
5 
more than from 0‘5 to 2 '5 per cent. ; it is dissolved out by hydrochloric acid, and the 
metal precipitated from the solution by scrap iron. The lead is contained in small 
crystals throughout the mass, and is separated from the sand by maceration and washing ; 
some of the rock contains as much as from 30 to 40 per cent, of the ore. 
The sandstone from which the vanadium precipitate was prepared possesses a light 
colour, and contains from 0 1 to O' 3 per cent, of the oxides of cobalt, nickel, and copper 
disseminated as small black, green, and red specks throughout the mass. After crushing, 
the metals were dissolved out by hydrochloric acid ; bleaching liquor and milk of lime 
were then added to alkaline reaction ; a portion of the copper, together with the whole 
of the nickel and cobalt, remained in solution, whilst the lead, iron, arsenic (partly derived 
from the acid used), a little copper, and the vanadium were precipitated. As the Mottram 
mine is now closed I have been unable to obtain a sample of the above-mentioned sand- 
stone for examination, and therefore I cannot state positively whether the vanadium 
occurs as vanadinite, although for other reasons I am inclined to think that it does. 
The above-mentioned lime precipitate was believed by the manager of the mines to 
contain about 10 per cent, of copper ; but when it was dissolved in acid and the copper 
thrown down by zinc, the solution still retained a bright blue colour, which I soon recog- 
nized as being due to vanadium. A rough analysis of the crude lime precipitate shows 
that it contains about 2 per cent, of vanadium, together with lead, arsenic, iron, lime, and 
sulphuric and phosphoric acids. 
In order to prepare pure vanadium compounds in quantity from this material, I w r as 
glad to avail myself of the kindness of my friends Messrs. Roberts, Dale, and Co., who 
were good enough to place their works at my disposal for this purpose. Three cwt. 
of the crude material was dried, and then finely ground with four times its weight of 
coal, and the mixture well furnaced with closed doors for several days until the greatest 
part of the arsenic had been driven off. The coal having been thus burnt off, the mass 
was then ground up with one quarter of its weight of soda-ash, and well roasted in a rever- 
beratory furnace with open doors for two days, to oxidize the vanadium to a soluble 
vanadate ; the mass was next lixiviated, and the solution drawn off from insoluble mat- 
ters: the liquid was acidified with hydrochloric acid, and sulphurous acid was then 
passed into the solution to reduce the arsenates, when the remaining arsenic was preci- 
pitated by sulphuretted hydrogen. 
The deep-blue solution thus obtained was carefully neutralized by ammonia (an excess 
causes much of the vanadium to pass into solution), the precipitated vanadium oxide 
washed on cloth filters, oxidized by nitric acid, and evaporated to dryness. The well-dried 
crude vanadic acid was then boiled out with a saturated solution of ammonium carbonate, 
which left iron oxide and calcium sulphate, alumina, &c. insoluble, and the filtrate eva- 
porated until the insoluble ammonium vanadate separated out. This crude vanadate was 
then washed with sal-ammoniac solution to free it from soda-salt, and recrystallized. In 
order to prepare from this salt pure vanadic acid, it was roasted in the air and the powdery 
acid obtained was suspended in water, into which ammonia gas was passed ; the dissolved 
