314 



STATE BOARD OF AGRICULTURE. 



TABLE 19. — Rate and extent of solubility of orthoclase which teas first treated with salt solutions and then 

 washed until all soluble salts were eliminated. Ratio of mineral to distilled water was about 1 to 0.75 

 and mixture maintained at room temperature. Figures represent freezing point depression. 



The above data show that the treatments of the rocks and minerals used 

 with the various salt solutions influenced very little if any the rate and ex- 

 tent of their solubility. It will be readily seen that the increased solubility 

 is very slight over the checks. The greatest increase generally occurred in 

 the (NH4)2S04, NaNOs, NaCl and NaC.HaOa treatments and the least in 

 CaH4(P04)2 and KH2PO4. 



The treatment of salts, therefore, did not have as marked influence on 

 the solubility of rocks and minerals as the}^ did on soils. The results with 

 rocks and minerals resemble ver}^ much those of cjuartz sand. 



THE SOLUBILITY OF ROCKS AND MINERALS IN THE PRESENCE OF SALTS 



In the preceding study only the residual effect of salt treatments on the 

 solubility of rocks and minerals could be studied. In order to ascertain 

 if the presence of salts for long periods in contact might have a greater effect 

 upon the solubility of rocks and minerals, an investigation upon this subject 

 was undertaken. It consisted of treating 20 grams of powdered rocks and 

 minerals with 15cc. of N/10 solutions of Ca(N03)2, NaNOs, KNO3, KCl, 

 (NH4)2S04, NaCl, K2SO4, CaH4(P04)2, KH2PO4 and NaC2H302, and deter- 

 mining the freezing point immediately and at various intervals thereafter 

 for long periods. The solubility effect and reaction could be ascertained frcm 

 the difference in the freezing point depression between that of the solution 

 alone and of the solution and soUd, and from the difference in the freezing 

 point depression at the various periods. Some of the typical results obtained 

 are detailed in tables 20 to 22 inclusive. 



