308 



STATE BOARD OF AGRICULTURE. 



TABLE 14. — Effect of heating under pressure on the solubility of powdered rocks when the ratio of rocks to 

 distilled water was about 1 to 0.75 and mixture maintained under a pressure of about 23 pounds for 

 about 8 hours. Figures represent freezing point depression. 



Biotlte granite 



Compact lithographic limestone. 



Crumbled mica schist 



Dlorite 



Hornblend gabbro 



Marble (dolomitic) 



Peridotlte 



Red roofing slate 



Siliceous dolomite 



Shale 



Syenite 



Quartzlte (baraboo) 



at 53° C 

 temperature 

 for 95 days. 



C°. 



.060 

 .048 

 .047 

 .082 

 .071 



* 



.034 



.278 



*Tubes broke. 



A comparison between the first two columns to the left in the above tables 

 reveals at once the fact that heating the rocks and minerals under a steam 

 pressure of 26 pounds, which is equivalent to a temperature of 117°C, for 

 8 hours, markedly increased their solubility product, and this increase was 

 greater in some rocks and minerals than in others. The increase varies from 

 in kaohnite to 0.032° in apatite, to 0.069 in marble to 0.095 in serpentine. 



By comparing the last two columns to the right, however, it is immediately 

 seen that the increase of solubility under the steam pressure was not any- 

 where as great, especially in some rocks and minerals, as that at the tem- 

 perature of 53°C at the end of 95 days. Under steam pressure, for instance, 

 the depression of the amphibole was only 0.032,° and serpentine 0.115°C, 

 while at the temperature of 53°C at the end of 95 days it was 0.124° and 

 0.340°C respectively. Evidently, therefore, the steam pressure of 26 pounds 

 for 8 hours did not produce the same amount of solubility as the temperature of 

 53°C for 95 days. 



Under steam pressure the solubility was affected not only by the tempera- 

 ture but probably also by pressure. To what extent the latter influences it 

 cannot be stated. 



RATE AND EXTENT OP SOLUBILITY OF UNLBAOHED ROCKS AND MINERALS 

 WHEN THE RATIO OF iSOLHD TO LIQUID WAS 1 TO 5, AND MIXTURE MAIN- 

 TAINED AT ROOCM TE3HPEEATURE AND AIjSO AT A TEMPERATURE OF 53°C. 



Definite compounds, at any given temperature have a definite solubility 

 which is independent of the relative masses of solid and liquid. In the case 

 of soils it was found that their solubility product depended upon the relative 

 masses of sohd liquid. In order to ascertain more definitely than is indicated 

 by the foregoing results, if the solubility of minerals and rocks is also inde- 

 pendent of the relative masses of solid and liquid a series of experiments 

 were performed. The procedure consisted of adding 25 cc of distilled water 



