HSTOEGANIC COMPOSITION OP SOME AMEEICAN SOILS. 27 



case. But in both these cases the other potash mineral, i. e., feldspar 



or mica, was present, and in large amounts. Therefore the potash 



in any of these soils was not only that held by physical or indefinite 



chemical absorption, but that contained in original minerals which 



will slowly yield their potash to the soil solution by decomposition 



extending through a long period of time. 



It is interesting to note that zeolites and rare earth minerals were 



not recognized. 



CONCLUSIONS. 



(1) The rarer elements, chromium, vanadium, rare earths, zirconium, 

 barium, strontium, lithium, and rubidium, were present in all soils ex- 

 amined. Chromium ranged from a trace to 0.025 per cent; vanadium, 

 from 0.01 per cent to 0.08 per cent; rare earths, from 0.01 per cent to 

 0.08 percent; zirconium, from 0.003 per cent to 0.08 per cent; barium, 

 from 0.004 per cent to 0.360 per cent; strontium, from 0.01 per cent 

 to 0.11 per cent. Lithium was found in spectroscopic traces only. 

 Boron is indicated in 18 soils by the presence of tourmaline and 

 fluorine in 24 soils by the presence of micas. 



(2) Molybdenum was found in only two samples, the surface soils 

 of the Durham sandy loam and the York silt loam. 



(3) Caesium was found in only one soil. 



(4) While it seems likely that copper, nickel, and cobalt are 

 present in soils, neither the amounts nor even the presence of these 

 elements has been established with certainty. 



(5) Silica is higher in the surface soil than in the subsoil, and 

 aluminum, iron, and, generally, titanium, are higher in the subsoil. 

 Potash and magnesium are higher in the subsoil. Manganese and 

 phosphorous concentrate in the surface soil. 



(6) The sulphur content is low, ranging from 0.03 per cent S0 3 

 to 0.39 per cent S0 3 with an average of 0.13 per cent. 



(7) The evidence that soils contain the more important rock- 

 forming minerals is strengthened by the mineralogical examinations 

 described. 



(8) There is an abundance of potash minerals in the soil. Samples 

 Nos. 2 and 3, Decatur clay loam, do not contain potash mica in 

 determinable amounts, though there are large quantities of potash 

 feldspars present. Samples Nos. 21 and 22, York silt loam, do not 

 contain determinable amounts of potash feldspars, but to offset this 

 there are large quantities of potash mica. Taken to a depth of 3 

 feet the potash mineral content of the soil varied from 43 to 2,000 

 tons to the acre. 



WASHINGTON : GOVERNMENT PRINTING OFFICE : 1914 



