[1] “The Soil Analyses of the Geological Surveys of Kentucky and Arkansas.” S. W. Johnson in Am. Jour. Sci., Sept. 1861.
[2] U. S. Geol. Survey, Professional Paper No. 14, p. 108.
[3] A trifling amount of chlorin is found oxidized in the form of sodium perchlorate, in the nitre deposits of Chile.
[4] See Rocks, Rock-weathering, and Soils, page 246; also paper on Domes and Dome Structure, by G. K. Gilbert, in Bulletins of the Geol. Society Am., Vol. 15, pp. 29-36.
[5] Collected by Dr. W. E. Ritter of the University of California.
[6] The term “overplaced,” used for such soils in late memoirs of the U. S. Geological Survey, is at least superfluous, in view of the perfectly understood term already in general use, and does not seem to commend itself for adoption by any special or superior fitness; nor does the suggestion of Shaler (The Origin and Nature of Soils, 12th Rep. U. S. Geol. Survey) to include the colluvial soils within the alluvial class, commend itself either from a theoretical or practical point of view, since but few useful generalizations can apply to both classes.
[7] Geikie, “Text-book of Geology,” 3d ed.
[8] Owing to the universal presence of water (H₂O) in air as well as in soils, it is usual and convenient to speak of carbonic dioxid (CO₂) gas when so occurring as carbonic acid (H₂CO₃), of which it produces the effects (CO₂ + H₂O = H₂CO₃).
[9] See Chapter 18.
[10] The increase of solvent power on feldspar when carbonated instead of distilled water is used, was well exemplified in an experiment made by Headden (Bull. 65, Color. Exp’t Sta., p. 29), who allowed pure distilled and carbonated water respectively to act on fresh but finely pulverized feldspar, with frequent shaking, for five days. The distilled water dissolved .0081 gram, the carbonated water, .0723 gram of solids, or nearly nine times as much as the distilled water. Both residues gave strong reactions for potash with platinic chlorid.