and on some other Compounds of Vanadium. 213 



yellow by transmitted light, which dissolved green in muriatic 

 acid without neutralizing it. None of these on being dissolved 

 in alkali and neutralized, produced precipitates in the metallic 

 solutions, similar to those with vanadiate of ammonia, and 

 therefore none appeared to contain vanadic acid ; nor did I 

 succeed in obtaining a solution of the brown precipitate in an 

 acid, either neutral or which could be neutralized with am- 

 monia, without precipitation; a difficulty which I attribute to 

 its absorption of oxygen in washing. Attempts to obtain more 

 of it by boiling the other oxides with de-oxydating substances 

 were also frustrated by the difficulty of separating it after- 

 wards. 



The solutions and precipitates were then mixed with nitric 

 acid in excess, and boiled together to dryness; redissolved in 

 solution of potash and boiled until colourless; slightly acidu- 

 lated with muriatic acid ; precipitated with muriate of barytes ; 

 and reconverted into vanadiate of ammonia, as above. A small 

 bulb was then blown on a bit of glass tube, which was drawn 

 out at half an inch from the bulb, and cut off, in the con- 

 tracted part, so as just to allow the vanadiate of ammonia to 

 enter. This salt was mixed with about half as much carbo- 

 nate of ammonia, and put into the bulb, which it filled. The 

 orifice was then nearly closed, at a spirit lamp ; the neck 

 thrust into the end of a quill, which was stuffed up with tow 

 from the other end, so as very much to impede the access of 

 air. The bulb was then heated over a spirit lamp, till am- 

 monia ceased to pass off: yet the oxide thus prepared did 

 not yield either a neutral solution, or one disposed to crystal- 

 lize, with sulphuric acid; and contained itself a large propor- 

 tion of acid. Nor did it, after various experiments, give re- 

 sults which could elucidate those above related. 



Vanadium gives, particularly in the reducing flame, a green 

 bead with borax, of a tint rather yellower than that from 

 chrome. 



Upon the whole the brown powder appears to me to be 

 hydrate of the protoxide; the purple, a combination of that 

 substance with the deutoxide ; and die crystals, the same com- 

 bination, but with the protoxide in larger proportion. The 

 deutoxide seems to possess acid properties; to be soluble in 

 acids as well as alkalies; and to yield, with metallic solutions, 

 precipitates different from those witli vanadic acid. 'I'he oxide, 

 both Ijrown and mixed, dissolves blue in acids; but the so- 

 lution becomes green by the addition of alkali, though still 

 liighly acidulous. The square crystals dissolve green in acids, 

 and the water becomes green when lying upon the surface of 

 the oxide, as it changes to purple. J lencc the solution of 



protoxide, 



