122 PROCEEDINGS OF THE AMERICAN ACADEMY 



1.3460 gr. lost on ignition 0.1405 gr. H 2 -f- NIT, = 10.44% 

 1.6407 gr. lost on ignition 0.1707 gr. H.,0 + NH, = 10.40% 

 1.2038 gr. gave 0.0430 gr. P 2 O r Mg 2 ="2.27% P 2 6 (twice precip.) 

 1.3960 gr. gave 0.0504 gr. P 2 7 Mg 2 = 2.31 % " 

 1.4890 gr. gave 0.0720 gr. NH 4 Q. = 2.35% (XH 4 ) a O 



These analyses lead to the formula 



24 WO, . P 2 5 . 3 (NH 4 ) 2 . 3 H 2 -f 26 aq. 



It will be observed that in this case the 24-atom salt was obtained 

 under conditions which a priori should have yielded a 20-atom salt. I 

 have already stated that salts of urea are precipitated from their solu- 

 tions by acid sodic phospho-tungstate 24 W0 3 . P 2 O s . 2 Na 2 . 4 H 2 0. 

 The precipitation is, however, not complete, and the process does not 

 appear to be available as a method of analysis. 



"When phosphate of aniline and 10 : 4 sodic tungstate are dissolved 

 together, and the solution is boiled for a short time, chlorhydric acid 

 gives an abundant yellowish-white precipitate. On re-solution the 

 precipitate yields pale sulphur-yellow crystals, which are readily solu- 

 ble in alcohol. Phosphate of para-toluidin behaves in a similar man- 

 ner; the phospho-tungstate formed is readily soluble, and crystallizes 

 in long yellow silky needles. 



I did not succeed in making the insolubility of the acid ammonic 

 phospho-tungstate available in analysis, either for the determination 

 of ammonia or for that of phosphoric acid. For the last-named esti- 

 mation the phospho-molybdates appear to be far better adapted. 



24 : 3 Acid Barium Salt. — When 10:4 sodic tungstate is dissolved 

 and a small quantity of phosphoric acid is added, the hot solution gives 

 with baric chloride a heavy white flocky precipitate, which readily dis- 

 solves in hot dilute chlorhydric acid. The solution, after filtration from 

 a small quantity of flocky matter, is pale yellow, and after some time 

 deposits splendid nearly colorless crystals, which appear to be octahe- 

 dra. These are readily soluble in hot water without decomposition, 

 and may be repeatedly recrystallized without difficulty. Of these 

 crystals. — 



