PROFESSOR EOSCOE’S RESEARCHES ON YANADIITM. 
11 
The fact that these older determinations all give a higher number than the above 
experiments, shows either that the acid was not fully oxidized, or, more probably, that 
the oxide was not completely reduced. It has already been stated (1) that the presence 
of the slightest trace of phosphorus prevents the complete reduction of the pentoxide to 
trioxide in hydrogen, (2) that all the naturally occurring vanadium ores contain phos- 
phorus which can only be detected, when present in small traces, by molybdic acid, a 
test unknown in Berzelius’s time, and (3) that the complete separation of phosphorus 
from vanadium is attended with great difficulty. Hence we may fairly conclude that 
the difference of 1T5 in the atomic weight between the above experiments and those of 
Berzelius is due to the presence of small traces of phosphorus in the vanadic acid used 
by the great Swede. 
IY. THE VANADIUM OXIDES. 
The oxides of vanadium of which Berzelius determined the composition were three 
in number : — 
1. The suboxide, or lowest oxide, obtained by reducing vanadic acid in hydrogen. 
This oxide Berzelius supposed to contain one atom of oxygen, and gave to it the formula 
VO=76-5. 
2. Vanadic oxide, to which Berzelius gave the formula V0 2 =84'5, founding his view 
upon the analysis of a hydrated sulphate as well as on that of the precipitated oxide 
dried in vacuo. 
3. Vanadic acid, V0 3 =92 5, was shown to contain three times as much oxygen as the 
suboxide. 
Berzelius describes several other intermediate oxides, but he did not isolate or analyze 
any of them. 
All these three oxides exist and possess in the main the properties which Berzelius 
assigns to them; they all, however, contain for every one atom of Berzelius’s vanadium 
(68*5) one additional atom of oxygen (0 = 16), with the existence of which he was unac- 
quainted. Besides these oxides, a still lower one has been found containing one atom 
less oxygen than Berzelius’s suboxide, and therefore having the atomic weight of Ber- 
zelius’s metal ; this oxide acts as a radical ; it may be termed vanadyl, VO, and may be 
supposed to exist in the higher oxides. 
Thus we have (V=5T3): — 
1. Vanadium dioxide, or vanadyl, V 2 0 2 . 
2. Vanadium trioxide (Berzelius’s suboxide), V 2 0 3 , or V 2 0 2 + 0. 
3. Vanadium tetroxide (Berzelius’s vanadic oxide), V 2 0 4 , or V 2 0 2 +0 2 . 
4. Vanadium pentoxide (vanadic acid), V 2 0 5 , or V 2 0 2 + 0 3 . 
1. Vanadium Dioxide (or Vanadyl ), V 2 0 2 =134 - 6. — In its power of uniting with 
oxygen vanadium surpasses even uranium, as observed by Peligot*. Like uranium, the 
* 
* Ann. de Ch. et de Phys. 3 ser. tomes v. xii. 
C 2 
