354: 



THE EEGOLITH 



E. H. Loughbridge has shown^ that the percentage of solnble 

 material in a soil rapidly increases with the degree of commi- 

 nution; i. e., the finer the material the larger the proportional 

 amount of soluble matter, and hence of matter available as 

 plant food. This is well brought out in the following table 

 abridged from the one given in Mr. Loughbridge's original 

 paper, the figures in the upper space of each column indicating 

 the size of the particles, and the percentage amount of each as 

 determined by fractional separations. 



Percentages of Soluble Matter in Soils 



Conventional Name: 



DlAMETBR OF PaRTIOIES : 



Constituents 



Insoluble residue 

 Soluble silica . 

 Potash (K2O) . 

 Soda (NaaO) . 

 Lime (CaO) 

 Magnesia (MgO) 

 Manganese (MnOg) . . 

 Iron sesquioxide (FeaOg) 

 Alumina (AI2O8) . . . 

 Phospboiic acid (P2O5) . 

 Sulphuric acid (SOs) . . 

 Volatile matter . . , 



Totals 



Total soluble constituents 



Clay 



2164% 



% 



15.96 



33.10 



1.47 



1.702 



0.09 



1.33 



0.30 



18.76 



18.19 



0.18 



0.06 



9.00 



100.14 

 75.18 



Fm:a!ST Silt 



2S.56 % 



mm. 

 .005-.011 



% 



73.17 

 9.95 

 0.53 

 0.24 

 0.13 

 0.46 

 0.00 

 4.76 

 4.32 

 0.11 

 0.02 

 5,61 



99.30 

 20.52 



Fink Silt 



12 54% 



mm, 

 .018-.016 



% 



87.96 

 4.27 

 0.29 



0.18 

 0.26 

 0.00 

 2.34 

 2.64 

 0.03 

 0.03 

 1.72 



100.00 

 10.32 



Mbdium 

 Silt 



18.6t% 

 .022-.02T 



% 



94.13 

 2.35 

 0.12 

 0.21 

 0.09 

 0.10 

 0.00 

 1.03 

 1.21 

 0.02 

 0.03 

 0.92 



100.21 

 6.16 



Ooabsb 



Silt 



18.11% 



mm. 

 ,088-.088 



% 



96.52 



96.52 



That the soluble constituents are, however, more available in 

 these more finely comminuted soils is perhaps an open question, 

 since, as pointed out by Van Hise,' the rapid solution of the finer 

 particles could very likely be more than counterbalanced by 

 the slower circulation of the underground waters. 



^On the Distribution of Soil Ingredients among the Sediments obtained 

 in Silt Analysis, Am. Jour, of Science, Vol. VII, 1874, p. 17. 



2 An excess of original amount, due to the addition of sodium chloride to* 

 produce fLocculation of clay in suspension. 



3 Treatise on Metamorphism, p. 155. 



