64 PROCEEDINGS OF THE AMERICAN ACADEMY 



0.0840 gr. gave with KMnO, 0.01778 gr. VO2 = 21.16% 

 0.1532 gr. « " 0.0659 gr. VP- =43.01% 



0.1612 gr. " " 0.0689 gr. " = 42.77% 



0.1625 gr. " " 0.0699 gr. " = 42.99% 



In the determination of the water by fusion with sodic tungstate, the 

 vanadic dioxide is oxidized to pentoxide. Hence it is necessary to 

 add to the percentage of water found — 15.06 — the 2:)ercentage of 

 oxygen required to convert 21.16% (mean) of VO^ to the equivalent 

 quantity of VgO. or 2.03%. This correction was not applied in the 

 case of the first salt described above, because after a rapid fusion the 

 vanadic dioxide appeared not to have been oxidized. In determining 

 the vanadic pentoxide in these salts the oxide is first reduced to VOg 

 by boiling with sulphurous acid and then titrated with hypermanganate. 

 From want of material the phosphoric oxide in the green salt was 

 determined by difference only. 



The analyses of the green salt correspond with the formula 



14 VO2 . 6 V2O5 . 7 K2O + 52 aq, 



Mean. 



29.65 (difF.) 



21.16 21.06 21.26 21.16 



19.73 19.82 19.80 19.58 



12.37 12.37 



17.09 17.09 



la this class of compounds I found it impossible to determine the 

 sum of the acid-forming oxides by precipitating directly with mercurous 

 nitrate and mercuric oxide. The results of many trials varied within 

 very wide limits. Both the black and green salts are oxidized when 

 heated with nitric acid and evaporated to degrees. Yellow crystalline 

 masses remain, which contain phospho-vanadates, and which deserve a 

 careful study as furnishing a new and perhaps better mode of forming 

 that class of salts. 



14: 16 : 6 Ammonic Phospho-vanadico-vanadate. — When ammo- 

 nic metavanadate or divanadate is boiled with a solution of ammonic 

 orthophosphate in large excess, a colorless liquid is formed, which 

 gives, with a solution of vanadic dioxide in chlorhydric acid, after a 

 time, beautiful black or rather intensely deep green crystals, exactly 

 resembling those of the potassic salt already described. The crystals 



