98 PROCEEDINGS OP THE AMERICAN ACADEMY 



was thrown upon a filter, washed on the filter-pump thoroughly with 

 cold water, and finally dried for analysis upon woollen paper. Of this 

 preparation, 



In the analyses the hypophosphorous acid was determined by oxida- 

 tion with bromine, after adding an excess of sodic carbonate. The 

 total phosphoric acid was then determined as ammonio-magnesic phos- 

 phate. In another portion of the salt the pliosphoric acid proper was 

 precipitated directly by magnesia-mixture in the usual manner. Cor- 

 rections are of course made for the loss of hydrogen in ignition, 

 according to the equation 



2 PO2H3 + HoO = P2O5 + 8 H, 



and also for the retention of one atom of oxygen by the mixed oxides, 

 as shown by the same equation. 



The analyses correspond to the formula 



4 PoO, . 9 KoO . NaoO + 43 aq, 

 PO . Oil} . 4 P2O, . 9 K.O . NaoO + 43 aq, 



8418 100.00 



It cannot be doubted that similar compounds containing molyb- 

 denum in place of tungsten remain to be discovered. I did not, how- 



