224 



Prof. Roscoe on Vanadium. 



[Dec. 19, 



The formula of vanadium pentoxide being Yfi-, and that of the oxide 

 obtained by reduction being Yg^a, the atomic weight of the metal is found 

 from the equation 



X ^ T 



a — 



where «=the weight of vanadium pentoxide taken, and 

 5= „ „ sesquioxide obtained. 



In each of the determinations a weight of not less than 5 grammes of 

 substance was operated on. 



Nos. 



1 .. 



Weight of vanadium 

 pentoxide taken. 



7-7397 ... 



Weight of vanadium 

 sesquioxide obtained. 



... 6-3827 .... 



Atomic weight 

 of vanadium. 



, 51-26 



2 , . 



65819 ... 



. . . 5-4296 . . . . 



. 51-39 



3 



■ 5-1895 . . 



... 4-2819 .... 



, 51-48 



4 . 



5-0450 . . . 



... 4-1614 



.. 51-35 



Hence the mean atomic weight from these experiments is 51-37, with a 

 mean error of + 0-066. Berzelius's number, calculated according to the 

 above equation, is 52'55. The difference is probably owing to the fact 

 that his vanadium contained a trace of phosphorus, which prevented the 

 complete reduction. 



lY. The Vanadium Oxides. 



(1) Yanadium monoxide, or vanadyl YO or Y2O2 



(2) „ sesquioxide (Berzelias's suboxide). . Y2O3 or Y2O2 + O 



(3) „ dioxide (Berzelius's vanadic oxide). . YO^ or Y^O^ + Og 



(4) „ pentoxide (vanadic acid) Y^O. or Y^O^ + Og 



(1) Vanadium Monoxide, YO = 67*2. — In its power of uniting with 

 oxygen vanadium surpasses uranium, as observed by Peligot ; and as this 

 oxide is found to enter into many of its compounds, the name Yanadyl may 

 appropriately be given to it. 



Yanadium monoxide is a grey powder possessing a metallic lustre, and 

 is obtained by passing the vapour of vanadyl trichloride, mixed with 

 excess of hydrogen, through a combustion-tube containing red-hot carbon. 



This oxide may be prepared in solution by. the action of nascent hydro- 

 gen, evolved by metallic zinc, cadmium, or sodium amalgam, upon a solu- 

 tion of vanadic acid in sulphuric acid. After passing through all shades 

 of blue and green, the liquid attains a permanent lavender tint, and con- 

 tains the vanadium in solution as monoxide. This compound absorbs 

 oxygen with such avidity as to bleach indigo and other vegetable colouring- 

 matters as quickly as chlorine, and far more powerfully than any other 

 known reducing agent. The degree of oxidation of the dissolved vanadium 

 was estimated by a standard solution of permanganate, which had been 



