EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 7 



obtained b}^ the latter investigator in determining the solubility of 

 the calcium phosphate (Ca3(P04)2,H,0) in carbonated waters and 

 in water containing both calcium carbonate and carbon dioxide are 

 given in Table I. 



Table I.- — SoluMlity of lime phosphate in water containing carbon dioxide and 



calcium carbonate. 



Solvent. 



Phosphoric 

 acid (PsOa) 

 per liter. 



Lime 



(CaO) per 



liter. 





Mg. 

 0.74 



6.9 



48.5 

 91.9 

 .38 

 1.1 

 .80 

 1.77 

 1.30 



Mg. 



1,200 cubic centimeters distilled water and 50 cubic centimeters water saturated 

 witliCO» 





1,000 cubic centimeters distUled water and 250 cubic centimeters water satu- 

 rated with CO" 





1,250 cubic centimeters water saturated with CO" 





Water containing 174 milUgrams CaCOa and 82 milligrams CO2 per liter 



Water containing 290 miUigrams CaCOa and 171 milligrams CO2 per liter 



Water containing 389 milligrams CaCOj and 270 milligrams CO2 per liter 



Water containing 488 milligrams CaCOa and 415 milligrams CO2 per liter 



Water containing 558 milligrams CaCOa and 541 milligrams CO2 per liter 



100.0 

 162.3 

 218.8 

 273.3 

 312.7 



It will be seen that the presence of carbon dioxide in water increases 

 greatly the solubility of tricalcium phosphate, but that the addition 

 of calcium carbonate depresses the solubility of the phosphate. This 

 experiment was apparently conducted with samples of relatively 

 pure materials, and no doubt the lime phosphate was in a precipi- 

 tated form. Under such conditions a greater quantity of phosphoric 

 acid (PoOs) would be dissolved than from the same quantity of 

 natural rock phosphate. 



An experiment to test the solvent power of carbonated waters on 

 various phosphatic materials was conducted by Williams^ many 

 years before the one just cited. The results of this experiment are 

 given in Table II. 



Table II. — Solubility in water of various phosphatic materials used as fer- 

 tilizers. 



Source of phosphate. 



Water re- 

 quired to 

 dissolve one 

 part of the 

 phosphate. 



Apatite from Perth, Canada, containing 89.27 per cent Ca3(P04)2 



Same, levigated 



Finely ground bone containiag 56.78 per cent Ca3(P0<)2 



Same, calcined to bum out organic matter, 92.88 per cent Ca3(P04)2 



Adulterated commercial bone dust containing 24.32 per cent organic and volatile matters 



and 35 per cent Ca3('P04)2 



South Carolina phosphate containing 57. S9 per cent Ca3(P04)2 



Same, levigated 



Guano containing 49.67 per cent Ca3(P04)2 



Parts. 



222,000 



140,000 



5,698 



8,029- 



4,122 

 6,983 

 6,544 

 ?,009 



»Chem. News, 24, 306 (1871). 



