AIR WA TEK SOILS. 



529 



Solubility of constituents of upland and lowland soils in water and in citric acid of different 



si ren ////is— Continued. 



Calcium 



oxid. 



Potas- 

 sium 

 ox id. 



Phos- 

 phoric 

 acid. 



Ferric 



aud 



aluminic 



oxids. 



Silica. 



lowland soils— continued 



In ,,'„ per cent citric acid: 



12 days 



33 days 



78 days : 



103 day s 



In water: 



2 days 



120 days 



Per cent. 



0.0110 

 . 0216 

 .0191 



.01411 



.0054 



.0170 



Per cent. 



0.0187 



.0326 



. 0245 



.0167 



.0047 

 .0168 



/'('(' Cfllt. 



0. 0005 

 .01112 

 .0011 

 . 0016 



.0030 

 .0004 



Per cent. 



Per cent. 



0.0199 

 .0144 



.0111 



0. 0043 



.0003 

 .0045 



''The most apparent result of the continued action of the dilute acid is seen in 

 the effect upon the phosphoric acid, and more notably upon the iron." 



" [In another series of experiments] the volume of water that the 

 soils could absorb was determined. That volume known, enough citric 

 acid was dissolved in it to make it exactly a -^ per cent solution, aud 

 the solution was applied to known weights of the upland aud lowland 

 soils, respectively, as follows: Three hundred and ninety grams of 

 water-free soil was put into beakers of 500 cc. capacity. . . . One-half 

 of the solvent was applied through tubes [reaching to the bottom of 

 the beakers], by which means the solution went to the bottom of the 

 soil and rose upward by capillarity, aud the other half was applied at 

 the top, somewhat later, which descended by gravity to meet the ris- 

 ing volume, thus securing the most even distribution throughout the 

 soil. The weight of each beaker was taken at the time of the first 

 application, when exactly the volume of solution was added to saturate 

 the soils. Every fourth day the weights of the beakers were retaken, 

 the volume of water that had been evaporated ascertained, and a vol- 

 ume equal to that lost by evaporation was added to each beaker, and in 

 this added water enough acid was dissolved to [restore the original 

 acidity of the solution]. This was done at intervals of 4 days aud con- 

 tinued for 120 days."' The solvents used in these experiments were 

 -^o and 1 per cent solutions of citric acid aud -^ per cent solution of 

 asparagin. 



Similar experiments, lasting 130 days, were made with a different 

 soil in galvanized iron pots holding 25 lbs. of soil. The results obtained 

 in the latter experiments are summarized iu the following table: 



Solubility of soil constituents in water and in citric acid of different strengths. 



Soluble in water: 



Natural soil 



Alter treatment with ^ per cent citric acid 

 After treatment with j£J per cent citric acid 

 After treatment with 1 per cent citric acid 

 Soluble in 1 per cent citric acid: 



Natural soil 



After treatment with ^ Tl per cent acid 



After treatment with Jj per cent acid 



After treatment with 1 per cent acid 



Calcium 

 oxid. 



Per cent. 



0. 0038 



. 0041 



.0045 



.0092 



.3410 

 .4342 

 .4544 

 .5056 



Potas- 

 sium 

 oxid. 



Per (••■at. 



0.0019 

 .0038 

 .0046 

 .0077 



. 0380 

 .0571 

 .0582 

 .0543 



Phos- 

 phoric 

 acid. 



Per cent. 

 0.0011 

 .0013 

 .0010 

 .0006 



.1270 

 .1498 

 .1408 

 .1482 



