210 Gooch and Gilbert — Ammonmm Vanadate, 



These results, representing determinations of the vanadium 

 pentoxide in the ammonium metavanadate after separation by 

 the same method used in determining the amount of pentoxide 

 in the vanadate taken, abundantly confirm the conclusions 

 reached by a consideration of the results of Table I. 



So it appears that the criticism of Rosenheim, obviously 

 made under a misapprehension of the details of the Gibbs 

 method, to which Milch, Liebert and Euler give their acqui- 

 escence, is unfounded. The process of Gibbs gives a practically 

 complete precipitation of ammonium vanadate, when to the 

 solution of the soluble vanadate such an excess of ammonium 

 chloride, with a little ammonia, is added, that the solution, after 

 concentration and cooling, deposits ammonium chloride, and 

 the mixture is allowed to stand twenty -four hours. Should 

 too much ammonium chloride for convenient handling crystal- 

 lize out on cooling, this is to be redissolved by the careful 

 addition of ammonia ; but care should be taken that after 

 standing, a little solid ammonium chloride and free ammonia 

 should still remain in the mixture. The precipitated ammo- 

 nium vanadate is to be washed with a cold saturated solution 

 of pure ammonium chloride, and the vanadium in the vanadate 

 determined by any appropriate means. Volumetric processes 

 are to be preferred to the slow ignition. We do not recom- 

 mend as a suitable procedure for ordinary use the complicated 

 modification of the Holverscheit method, which was employed 

 in this investigation in order that the same method of determi- 

 nation of vanadium might be used before and after the separa- 

 tion process. Reduction as suggested by Gibbs, and titration 

 by permanganate or the iodimetric estimation of Browning,* 

 should be of service in ordinary cases. 



* Zeitsclir. Anorg. Chem., vii, 158. 



