688 
PROSESSOR ROSCOE’S RESEARCHES ON VANADIUM. 
Another reaction consisted in passing the vapour of oxytrichloride mixed with hydro- 
gen over metallic sodium heated in a porcelain boat ; a black shining powder was thus 
obtained, which after lixiviation and drying was burnt to vanadium pentoxide, and 
gained only 11 per cent, in weight. 
The only methods which promised possible results were: 
1. The reduction of a vanadium chloride (free from oxygen) in hydrogen gas. 
2. The reduction of the mononitride in a current of hydrogen. 
The first of these methods has been found to be successful, the second does not appear 
to yield the metal ; for in two experiments in which the mononitride was ignited in a 
platinum-tube to whiteness in a current of hydrogen, in one case for 3| and in another 
for 2 hours, the loss of weight was only 8’8 and 8’4 per cent, respectively, whereas the 
nitride must lose 21-4 per cent, when converted into the metal. 
Reduction of the Metal from Vanadium Dichloride in Hydrogen . — The only method 
by which it has been found possible to obtain metallic vanadium is by the reduction of 
a chloride free from oxygen, in an atmosphere of perfectly pure hydrogen. Although 
this process appears simple enough, yet there is, I believe, no metal more difficult to 
obtain than vanadium. 
This arises from the circumstance that while vanadium appears to be stable at ordinary 
atmospheric temperatures, it absorbs oxygen at a red heat with the greatest avidity, and 
that therefore every trace of air or of moisture must be excluded. Another difficulty 
consists in the preparation of sufficiently large quantities of the solid chlorides free from 
oxygen or moisture, as also in the length of time necessary in order to reduce these 
chlorides in hydrogen at a red heat, during which time diffusion (which can never be 
wholly prevented) brings traces of oxygen in contact with the heated metal. 
Then, again, the destructive action of the metal on glass and porcelain prevent these 
substances being used to contain the metal, whilst tubes of platinum and wrought iron 
become so porous at a red heat as to admit sufficient oxygen to convert the whole 
vanadium into trioxide. The only means which can be adopted is to heat the chloride 
in a platinum boat placed in a porcelain tube. 
A laborious series of preliminary experiments on the reduction of the metal in this 
way proved that, in order to obtain a substance even approaching to the metal, many 
precautions must be taken, whilst they showed that, in spite of every care, it is extremely 
difficult to obtain the metal itself. Thus no less than ten experiments made by different 
modifications of this method yielded mixtures of metal with more or less oxide, of which 
the analyses showed an increase on complete oxidation varying from 60 to 67 per cent., 
that for pure metal being 78, whilst in every case in which the pure metal was prepared 
a considerable quantity of black sesquioxide was formed at the end of the boat nearest 
the inflow of hydrogen, showing that the source of error lay in the presence of diffused 
oxygen. 
The apparatus which, after many alterations, was found best adapted for the prepara- 
tion of the metal is represented on fig. 2. 
