A. A. Ramsay 279 



The calculations involved are based upon the following considera- 

 tions: dicalcic phosphate contains 1 part CaO -1607 parts water of 

 crystalhsation^ 1-26786 parts P2O5; tricalcic phosphate contains 1 part 

 CaO with -84524 parts P2O5 ; calcium hydrate contains 1 part CaO with 

 •3214 parts water. 



In mixtures containing di- and tricalcic phosphates, when the total 

 CaO and total P2O5 are determined the amounts of di- and triphosphate 

 is calculated as follows : 



liCt X = CaO existing as dicalcic phosphate, 



and y = CaO existing as tricalcic phosphate ; 



then X X 1-26786 = Pjj05 existing as dicalcic phosphate, 



and y x -84524 ^PjjOj existing as tricalcic phosphate. 



l-26786a; + -84524?/ = total phosphoric acid found (1), 



x+ y = total lime found (2). 



Solving these equations the values of x and y are obtained. 



In mixtures containing dicalcic phosphate (CaHP042H20), tricalcic 

 phosphate (CaaPaOg) and calcium hydrate (CaOHgO), having determined 

 the total CaO, total P2O5 and water, the following is the method adopted : 



Let .T = CaO as dicalcic phosphate, 2/ = CaO as tricalcic phosphate, 



2 = CaO as calcium hydrate. 



■1607a;+ -6428;/ + -3214; =-- total water detcrmine^l (1), 



x+ y+ 2 = total lime determined (2), 



1-26786X + -84524?/ :=total P.Oj determined (3). 



From (1) obtain value of z in terms of x and substitute in (2), equate 

 this with (3) and obtain value of x. y and z are then found. 



The following three samples, Nos. 1, 2, and 3, of phosphate of lime 

 were obtained by purchase. 



No. 1. Phosphate of lime in a 1 lb. bottle and of English manu- 

 facture. 



This sample was found by analysis to contain : 



Lime (CaO) 48-26 



Phosphoric a. 'id (PoOj) 43-26 



Water 8-48 



100-00 



Per cent. 

 Loss in weight on drying in desiccator over sulphuric acid in 16 hours ... 1-036 

 Loss in weight on drying in desiccator over sulphuric acid in 112 hours ... 1-620 

 Loss on drying at 100° C. in 2 hours, 2-37 % in 4 hours ... ... ... 2-37 



Loss on ignition 8-47 



19—2 



