L82 On Tribasic PhospJwric Aii</. 



1 (responding to a composition of 

 6.86 PO 

 33.23 IV < I 

 29.91 BO=16.58=50 eq. 



11.:;:; 



29.91 

 B. 



I will, in the following experiments, describe the methods 

 with tin- Mit ik' ace u racy with which they were executed, though ] 

 am well aware thai I am giving nothing new. I will here re- 

 mark, that in precipitating phosphoric acid as ammonio-phos- 

 pbate of magnesia, the fluid was always evaporated to about 

 c. c, and the dissolved pan never taken into consideration. 



Of tin- magnesia mixture which was prepared in a most 

 careful manner, 50 c. c. sufficed to precipitate 1 gr. of phos- 

 phoric acid. Tin' three analyses by the Bame method were 

 always commenced at the Bame time, continued under the 

 same circumstances, ami finished with an accuracy ami patience 

 necessary in researches of this kind. I will give the methods 

 in the order of their exactness. 



I. Method with M<>.. 



The Bubstance wae dissolved in nitric acid, diluted with 

 water, ami heated with a sufficient amount "f molybdic acid 

 solution (Vide Fresenius, Qualitative Analysis). After cool- 

 ing, the yellow precipitate was Altered off, washed from the 

 filter and dissolved in a lonia. This solution was again pre- 

 cipitated bv dilute nitric acid, with the addition of a Little 

 molybdic acid Bolution, and after washing out completely the 

 nd precipitate, and dissolving it in ammonia, the solution 

 ed when necessary, evaporated, and then precipitated 

 with magnesia mixture. This precipitate of amnion io phoa 



