russell. j JEOLIAN SOILS. 137 
through a 200-mesh sieve similar vegetable fragments are present. 
Probably 3 to 4 per cent of each sample consists of vegetable debris. 
The soil represented by sample No. 1 is of a light-yellowish, nearly 
white color, and resembles the loess of the Mississippi Valley and 
other regions. The particles composing this sample, larger than those 
passing through a 200-mesh sieve, when examined with the aid of a 
microscope, are seen to consist of small grains loosely united and well 
rounded, probably on account of the slight attrition necessary to 
cause the material to pass through the sieves used. When these 
rounded grains are lightly rubbed in water, they immediately disinte- 
grate. The same result is attained by placing them in weak hydro- 
chloric acid, the spontaneous separation being accompanied by a brisk 
effervescence. The residue obtained after treating with acid, when 
examined under a microscope, is indistinguishable from the grains 
composing 82.8 per cent of the original sample, which pass through a 
20n-mesh sieve. The coarser particles are thus shown to be aggrega- 
tions of the liner grains present, loosely cemented by some carbonate, 
probably of calcium. The grains which pass through a 200-mesh 
sieve, as well as those obtained by treating the larger particles present 
in the original sample with acid, when examined under a microscope, 
are seen to be angular and subangular and mostly without color. 
From their appearance, resistance to acids, and other tests, they have 
been shown to be almost entirely grains of quartz. No shreds of 
glass, such as are characteristic of volcanic dust, were observed. 
Thus, as indicated by a mechanical analysis, the soils are composed 
essentially of exceedingly fine quartz sand, with a minor amount of 
some cementing material, probably calcium carbonate. This conclu- 
sion is sustained by a chemical analysis, the results of which are here 
presented. 
Chemical analysis of soil from near Shoshone Falls, Idaho. 
[Analyst, W. F. Hillebrand.] 
Per cent. 
Silica, Si0 2 52. 43 
Alumina, A1 2 3 7. 10 
Ferric oxide, Fe 2 3 2. 63 
Titanium dioxide, Ti0 2 38 
Manganous oxide, MnO Trace. 
Calcium oxide, CaO 14. 60 
Potassium oxide, K 2 1.7 
Sodium oxi< le, Na 2 93 
Magnesium oxide, MgO 2. !)."> 
Carbon dioxide, C0 2 12. 40 
Phosphoric oxide, P 2 5 20 
Water, H 2 4. 96 
Total „„..„. 100. 31 
