316 



STATE BOARD OF AGRICULTURE. 



TABLE 22. — Rate and extent of solubility of prochlorite in presence of salts. Ratio of solid to liquid 1 to 

 0.75 and mixture maintained at room temperature. 



The above experimental data reveal at least five very interesting points: 

 (1) that the reaction between the salt solutions and rocks and minerals is 

 very rapid if not almost instantaneous; (2) in all of the rocks and minerals 

 and in all of the salt solutions, the freezing point depression of the mixture 

 was slightly smaller than in the solutions alone, indicating that there was 

 a reaction between the solvent and the solute or solid ; (3) with the exception 

 of the CaH4(P04)2 and KH2PO4 mixtures, the depression in all of the other 

 mixtures remained almost constant, with a very slight tendency to increase; 

 (4) the depression of all the CaH4(P04) and KH2PO4 treated rocks and min- 

 erals decreased very greatl}^ indicating that the phosphate was being ab- 

 stracted by the powdered rocks and minerals; (5) salts had very little, if any, 

 increasing effect on the solubility of the various rocks and minerals. 



It will be of interest to mention here that the treatment of rocks and min- 

 erals with salts yielded exactly the same type of results as soils similarly 

 treated (4). 



SUMMARY 



In the present paper there are presented the results of an investigation 

 on the rate and extent of solubility of the most common soil-forming rocks 

 and minerals at different moisture contents, under different salt treatments, 

 and at various temperatures. 



The method employed in measuring the rate and extent of solubility was 

 the freezing point method. This method proved quite appropriate for the 

 purpose. 



It was found that when very fine powder of rocks and minerals in the un- 

 leached condition was mixed with clistilled water in the ratio of 1 of solid 

 to 0.75 of water, the amount of material that went into solution immediately 

 was quite appreciable in all the rocks and minerals and in some rocks and 

 minerals more than in others. The freezing point depression for instance, 

 varied from 0.008C° in quartz to 0.057° in ferrugineous sandstone, to 0.069° 

 in apophyllite. Expressing these depressions in p. p.m. of solution then the 

 concentration varies from 100 p.p.m. in quartz to 711 in ferrugineous sand- 

 stone, to 975 in apophyllite. 



