226 



Prof. Roscoe on Vanadium. 



[Dec. 19, 



Constitution of the so-called Monovanadates. — The analyses of Berzelius 

 serve to point out, when the new atomic weight is adopted, that these 

 compounds prove to be metavanadates ; thus — 



Berzelius's formulae. 

 (y=68-5. = 8.) 



Ammonia salt NH3YO3 + HO 



Barium „ BaOYOg 



New formulEe . 

 (Y=51-2. = 16. Ba=137.) 



NH 1 



Ammonium metavanadate NH^YOg or yQ ^ V 0^ 



Barium metavanadate BaY„0, 



or 



Ba \q 

 2Y0 J 



The bivanadates are anhydro-salts having the composition 2(NaYO)3 

 + Y,0^, or perhaps Na,Y,0, + 3 Y^O^ . 



Berzelius's analysis of this ammonium salt was carefully confirmed, ex- 

 periment showing that the salt yielded 7 7 '7^ per cent, of vanadium pent- 

 oxide, theory requiring 77'S2 per cent. The bivanadates analyzed by 

 Von Hauer prove to be anhydro-salts, analogous to certain chromates and 

 borates, and possessing the composition 2(NaY03)-f YgO.. 



The normal or ortho-vanadates are tribasic ; the sodium salt is NagYO^, or 



YQ I O3 ; this is shown by the fact that vanadium pentoxide (Y^O.), w^hen 



fused with sodium carbonate, displaces 3 molecules of carbon dioxide. 



It is the author's intention to investigate the composition of the vana- 

 dates at a future time. 



Y. Vanadium Oxychlorides, and Second Atomic Weight determination of 



the Metal. 



(1) Vanadium Oxytrichloride, or Vanadyl Trichloride,^ — Mole- 

 cular weight ]73"2. The fact that the lemon-coloured liquid chloride of 

 vanadium prepared by the action of chlorine upon the sesquioxide (Ber- 

 zelius) contains oxygen, contrary to the statements of previous experi- 

 menters, was ascertained (1) by obtaining carbon dioxide from the decom- 

 position of the vapour of the oxychloride passing over red-hot charcoal, (2) 

 by the production of magnesia by the action of magnesium, (3) by the for- 

 mation of caustic soda by the action of sodium, (4) by the formation of va- 

 nadium sesquioxide when the vapour of the oxychloride was passed with 

 pure hydrogen through a heated tube. 



The specific gravity of vanadyl trichloride was found to be 1'841 at 

 14°-5, audits vapour-density 88'2 (H=:l), or 6-108 (air= 1), and its boiling- 

 point 126'7 under 767'0 millims. (determined on 100 grammes of substance). 

 Yanadyl trichloride, most carefully purified, was analyzed many times with 

 every precaution, the chlorine being estimated both by Gay-Lussac's pro- 



