298 The SoluUlity of Calcium P7ios2)hates in Citric Acid 



only when the figure for free hme present is assumed or is known. 

 Assuming that (CaO)oH20P205 . 4H2O is the dicalcic phosphate present 

 and that the tricalcic phosphate is CaaPaOg and the hme present as 

 hydrate CaOHaO the following mixtures will contain 54-95CaO associ- 

 ated with 45-05P2O.r.. 



100-00 100-00 100-00 100-00 



and the ratio of hme to phosphoric acid would still be 



54-95CaO : 45-05P2O5. 



{(l) 54-93CaO and 45-O7P2O5. To produce Ca3P208, 45-07 grams 

 P2O5 would require 53-32CaO, whereas 54-93CaO is found present. 



The remarks under (c) hold here also. 



Since tricalcic phosphate has apparently not been obtained, the 

 conclusions drawn by Warington are not justified. 



The formula (3Ca3P208 . CaOH20) for the resulting product of boiling 

 the above phosphates with water is deduced not from an analysis of the 

 product but again from the ratio of CaO to P2O5 , the water of hydration 

 or combination present appears to be more or less problematical. 



However, assuming that the above formula approximates the com- 

 position of the resulting basic product it appears to be equally possible 

 that this is still a mixture of di- and tricalcic phosphate with lime for 

 2Ca3P208 .2CaHP04 . CaO or 2 (CaO)3P205 . (CaO)2P205 . CaOH20 would 

 agree equally well with the numbers found. 



Further investigations on this matter are therefore desirable. 



{Received Ajml llih, 191G.) 



