J. F. Tocher 



129 



IV. EXPERIMENTS WHERE THE QUANTITIES OF MINERAL PHOSPHATE 

 AND CITRIC ACID USED WERE CONSTANT AND THE DILUTION 

 WAS VARIED. 



In order to determine the variability in citric solubility of mineral 

 phosphate with varying dilutions of citric acid, a series of experiments 

 was conducted with different dilutions shaking for half an hour, the time 

 prescribed in the official test. The quantities of citric acid and of mineral 

 phosphate used are indicated in the following table (Table III). Let 

 m-^ = amount of citric acid used, itio ^ amount of mineral phosphate 

 used, and ni^ = volume of fluid used. In tliis series the ratio rn^jm^ was 

 made constant (and equal to 2) in order to secure that the effect of the 

 presence of Ca(0H)2 and of CaCOj and other hydrates and carbonates, 

 on the citric acid concentration was of a constant character. Throughout 

 this series of experiments 10 grams citric acid and 5 grams mineral 

 phosphate were used, the volume being varied as shown in Table III. 



Table III. Quantities of ininend phosphate and citric acid used are 

 constant — dilution, i.e. degree of concentration, varies. 



5 grams mineral phospliate 

 10 grams citric acid 



60 i 



oo 



gp;' 



a a 

 §■3 



20 



in (.'iihio ("'clitimetrcs 



500 1500 2500 



Diagram 1. See columns 8 and 9, Table III. 



sag 



S^-2 24 

 Sfea 22 



"So- 



Voiunic in ('nl>ic Centimetres 



500 1500 



Diagram 2. See column 5, 



2500 

 Table III. 



