Mr. J. Prideaux's Expetimeyifs oti Vanadiate of Ammonia. 209 



but he is wrong in supposing that a percarbonate is not pro- 

 cured by adding the carbonate to a solution of pernitrate : 

 I mixed sokitions of these salts and obtained a precipitate, 

 which had an ochre yellow colour ; it was dried by exposure 

 to the air, lost 4*4 per cent, by dissolving in dilute nitric acid, 

 and the solution when decomposed by soda gave 98*1 of per- 

 oxide; this salt is therefore a dipercarbonate, consisting of 



Two atoms of peroxide of mercury (216X2) = 432 or 95*2 

 One atom of carbonic acid = 22 4*8 



454 100-0 



XXVIII. Experiments on Vanadiate of Ammonia, and on 

 some other Comjmiinds of Vanadium. By Mr. John Pri- 

 de a ux, Meynber of the Plymouth Institution. 



To the Editors of the Philosophical Magazine and Annals. 

 Gentlemen, 

 TN the absence of detailed information on vanadium, a sum- 

 ■"- mary of experiments on the minute scale, on a portion of 

 vanadiate of ammonia, with which I was favoured in a letter 

 from Professor Berzelius, about a month since, may be not 

 unacceptable to your chemical readers. It was accompanied 

 by the information, that the atomic weight of vanadium is 

 855*87 : that it combines with 1, 2 and 3 atoms of oxygen, 

 with the latter quantity forming vanadic acid ; that by driving 

 off the ammonia, in an open vessel, the acid would be ob- 

 tained ; and that by the same process, out of access of air, the 

 oxide would be produced. 



The acid was the first subject of experiment. It is a dull 

 orange red powder, as described in your last Number, p. 152 ; 

 and the neutral salts it forms with alkaline and earthy bases 

 are white; which would hardly have been expected, consider- 

 ing the analogies of vanadium with chrome. With excess of 

 acid, however, they are yellow. 



1. Vanadiate of potash is very soluble, and showed no dis- 

 position to crystallize, although evaporated slowly to dryness, 

 with frequent intervals of cooling, and afterwards redissolved 

 and left to spontaneous evaporation. 



2. Vanadiate of soda is scarcely so soluble, but not more 

 disposed to crystallize. 



3. The (juantities employed amounting to only about 2 grains 

 of each salt, and the indisposition to crystallize being perliaps 

 due to the smallness of the tjuantity, the two solutions were 

 mixed and al)and<)ned to spontaneous evaporation ; the glass 



N.H. Vol. 10. No. 57. Sept. 1831. 2 E being 



