318 



Prof, Roscoe on Vanadium. 



[Apr. 7, 



distilled almost without decomposition. Vanadium oxytribromide dissolves 

 in water, yielding a yellow-coloured solution, in which both vanadium and 

 bromine were determined, after reduction with sulphurous acid : — 



Calculated. Mean of several analyses. 



V = 51-3 16-69 16-75 



Br 3 =2-10-0 78*10 79-20 



O = 16-0 5-21 



307*3 100-00 

 The specific gravity of the oxytribromide at 0° is 2-9G7. 

 3. Vanadium Oxydibromide, or Vanadyl Dibromide, VOBr 2 , molec. 

 wt. = 227*3. — This is a solid substance, of a yellowish-brown colour, 

 obtained by the sudden decomposition of the foregoing compound at tem- 

 peratures above 100°, or by its slow decomposition at the ordinary tem- 

 perature. 



The oxydibromide is very deliquescent, dissolving in water, with forma- 

 tion of a blue solution of a vanadious salt. When heated in the air it loses 

 all its bromine, and is converted into V„ O.. 



Analysis gave : — 



Calculated. Mean of several analyses. 



V ss 51-3 22-57 22-45 



Br 3 =160-0 70-39 70*93 



O ,.= 16-0 7*104 



227-3 100-00 



III. Vanadium and Iodine. 

 Iodine-vapour does not attack either the trioxide or the nitride at 

 red heat ; both these substances remain unchanged, and no trace of vana- 

 dium can be detected in the iodine which has passed over them. 



IV. The Metallic Vanadates. 



In the first part of these Researches (Phil. Trans. 1868) it was pointed 

 out (1) that the salts analyzed by Berzelius must be considered as meta- or 

 monobasic vanadates, (2) that the so-called bivanadates analyzed by Von 

 Hauer are anhydro-salts, and (3) that the ortho- ortribasic vanadates con- 

 tain 3 atoms of monad metal, the sodium salt being formed artificially by 

 fusing 1 molecule of vanadium pentoxide with 3 molecules of carbonate of 

 soda, when 3 molecules of carbon dioxide are expelled, whilst the ortho- 

 salts occur native in many minerals. The present communication contains 

 a description of these classes of salts, as well as of a new class of salts, the 

 tetrabasic or pyro-vanadates. 



Sodium Vanadates. 



1. Ortho- or Tri-Sodium Vanadate, Na 3 V0 4 + 16H 2 0 2 .— When a mix- 

 ture of 3 molecules of Na 2 C0 3 and I molecule of V 2 0 6 is fused until no 



