62 PROCEEDINGS OF THE AMERICAN ACADEMY 



but we have at present no data for deciding the question. The solu- 

 tion in cold water gives brown flocky precipitates with salts of silver 

 and thallium and with mercurous nitrate, none with baric chloride at 

 first, but after a short time the mixture becomes turbid and then 

 deposits distinct orange crystals mixed with a brown flocky matter. 

 The salt is therefore probably decomposed by solution. 



4:5:1 Phospho-vanadico-vanadate of Sodium. — A boiling solu- 

 tion of sodic orthophosjjhate dissolves the mixture of vanadic oxides 

 obtained by igniting amnionic metavanadate, and gives a greenish 

 liquid which on cooling deposits green crystalline scales with a talcose 

 lustre. The same salt is formed by fusing together the mixed oxides 

 and sodic phosphate, but is in this way more difficult to obtain in a 

 state of purity. The comjiound is insoluble in water, and cannot 

 therefore be purified by recrystallization. Of this salt, 



1.4264 gr. lost on ignition 0.3904 gr. = 27.37% water 



1.2893 gr. gave 0.8136 gr. V^O^ + PA =63.10% 



1.7149 gr. " 0.5815 gr. V/)^ by titrition with KMnO^ = 33.90% 



1.4190 gr. " 33.67% and 33.75% 



The analyses correspond tolerably well with the formula 

 5 PA . 4 V2O5 . VO2 . 4 Nap -f 37 aq. 



2439 100.00 



12:12:6 Potassic Phospho-vanadlco-vanadate. — When solutions 

 of potassic divanadate and potassic orthophosphate, PO^K.^H, are 

 heated together, the phosphate being in large excess, a colorless solu- 

 tion is formed. A solution of vanadic dioxide in a large excess of 

 chlorhydric acid then often produces almost immediately a precipitate 

 of black granular crystals. In some cases, however, the black salt is 

 formed only after standing some hours. Under the microscope the 

 black crystals appear to be cubes, though this is rather uncertain. 

 The true color is deep green. The salt is insoluble in water contain- 



