70 PROCEEDINGS OF THE AMERICAN ACADEMY 



1.0728 gr. gave 0.8133 gr. Mo0 3 + P 2 5 = 75.81% 

 1.4520 gr. " 0.4719 gr. P 2 0. = 2.96% 



This corresponds to 72.85% Mo0 3 by difference, and 24.19% of 

 CcO and water by the loss. The analyses agree very closely with 

 the formula 



24 Mo0 3 . P 2 0. . CcO . 2 H 2 -f 21 aq, 



which 



Under the microscope this salt is seen to consist of fine yellow felted 

 needles. It is very slightly soluble in cold water, but is soluble in a 

 rather large quantity of boiling water, giving an orange-yellow solution, 

 with a strongly acid reaction. The solution gives with argentic nitrate 

 a very insoluble sulphur-yellow flocky precipitate, which after a time 

 becomes crystalline, and a pale yellow flocky precipitate with mercu- 

 rous nitrate. No precipitate is formed with cupric sulphate or baric 

 chloride. The salt could not be recrystallized ; it is interesting as a 

 particularly well-defined soluble acid salt of the 24 : 1 atom series. 



24 : 2 Acid Potassium Salt. — This salt was prepared by boiling 

 together solutions of potassic molybdate and phosphate, adding an ex- 

 cess of nitric acid, and boiling the whole for some time. As in the 

 case of the ammonium salts, the precipitation is greatly facilitated by 

 this process, taking place very slowly in the cold. The salt obtained 

 was in very minute crystals, bright yellow, and but slightly soluble in 

 cold water. Of this salt, — 



0.7772 gr. lost on ignition 0.0128 gr. = 1.64% water 



0.7962 gr. " " 0.0130 gr. = 1.66% " 



1.1703 gr. gave 1.0895 gr. MoO s + P 2 0. = 93.10% 

 1.3263 gr. " 0.0779 gr. P 2 7 Mg 2 ' = 3.76% P 2 5 

 1.3033 gr. " 0.0778 gr. « = 3.82% « 



The phosphoric oxide was twice precipitated as ammonio-magnesic 

 phosphate. The analyses correspond with the formula 



24 M0O3 . P 2 5 . 2 K 2 . H 2 + 3 aq, 



which requires : — 



