EXPERIMENT STATION BULLETINS. 



307 



at the high temperature is that even though the rocks and minerals are 

 cooled to two or three degrees below zero centigrade the solubility product 

 still remains high, indicating that they have not j'et reached equilibrium or 

 the saturation point at the temperature of 53°C. 



EFFECT GIF HIGH TBMPEiRATUJRiE UMDiBR riRESSURE OP THE SOLUBILITY OF 



LEACHED ROCKS AND MINiERADS. 



Since the foregoing study showed very conclusively that a temperature 

 of about 53°C had a very marked increasing effect on the solubility' of nearly 

 all the rocks and minerals, a desire arose to investigate the influence on sol- 

 ubility of a greatly higher temperature but at a shorter period. According- 

 ly, into a second series of freezing point tubes were placed equal amounts of 

 leached powder of rocks and minerals and distilled water as were employed 

 in the previous temperature series, and each tube carefully weighed. All 

 the tubes then were set in an autoclave and heated for 8 hours at about 26 

 pounds steam pressure. This steam pressure is equivalent to a temperature 

 of 117°C. The tubes were then taken out after cooled, brought back to 

 the original weight by the addition of distilled water, and the freezing point 

 depression of their contents determined. In table 13 and 14 are presented 

 the data obtained. For convenient and immediate comparison the depress- 

 ion before heating and that at the temperature of 53°C are given in the same 

 tables. 



TABLE 13. — Effect of heating under pressure on the solubility of leached powdered minerals when the ratio 

 of minerals to distilled water was about 1 to 0.75 and mixture maintained under a pressure of about 

 26 pounds for about 8 hours. Figures represent freezing point depression. 



Apatite 



Amphibole 



Apophyllite 



Calcite 



Epidote 



Gypsum 



Hematite (micaceous) 



KaoUnite 



Limonite 



Oligoclase 



Orthoclase 



Prochlorite 



Serpentine 



Siderite 



Stilblte 



Talc 



Zircon 



Before 

 heating. 



C°. 

 .010 



Heated under 



pressure 



for 8 hours. 



C°. 

 .042 



At 53° 

 temperature 

 for 95 days. 



C°. 



.077 



.124 

 .055 

 .060 



.069 



.014 

 .045 

 .114 

 .073 

 .030 

 .340 



.038 

 .048 



