The Results of X‐Ray and Microscopical Examinations of Soil Colloids

Minerals of the montmorillonite group, their origin and relation to soils and clays

“…Progress of this work has been recorded in a number of papers by Hendricks (1936,1938,1939,1941,1942), Hendricks and Alexander (1939, 1940a, 1940b, Hendricks and Fry (1930), Hendricks andJefferson (1938, 1939), Hendricks, Nelson, and Alexander (1940), Hendricks and Ross (1938), and Ross (1943).…”

“…The presence in soils of minerals related to the micas was first recognized by Hendricks and Fry (1930). Ross and Shannon (1926) gave an analysis of potash-bearing bentonites of Ordovician age and of a similar clay frorri China.…”

Reconsideration of theoretical basis of Freundlich adsorption isotherm equation

“…The study of permanent-charge soils has a long history (Sposito 1980a). In 1930s, soil chemists found that these soils contained a large amount of the layer silicate minerals (Hendricks and Fry 1930). Marshall (1935) attributed the origin of the surface charge of these minerals to the charge deficit resulting from isomorphic substitutions.…”

Role of Chemical Properties of Clays in Soil Science

“…The application of petrograpliic and X-i-ay techniques to the study of minerals in colloidal clay of soils dates back over a remarkably brief span of years to 1930, when the epoch-making-papers of Hendricks and Fry (1930) and Kelley, Dore, and Brown (1930) appeared independently and almost simultaneously, announcing that the inorganic colloidal material of soils was not an amorphous, indeterminate mixture of oxides, as had hitherto been supposed, but a definitely crystalline material. This important finding was, in effect, a confirmation of the results announced in 1927 by C. S. Ross (1927) to the effect that the clay minerals, notwithstanding their colloidal dimensions, exhibit definite crystallographie constants determinable with the petrographic microscope.…”

“…This important finding was, in effect, a confirmation of the results announced in 1927 by C. S. Ross (1927) to the effect that the clay minerals, notwithstanding their colloidal dimensions, exhibit definite crystallographie constants determinable with the petrographic microscope. Hendricks and Fry (1930), applying both petrographic and X-ray techniques, found that the colloidal clay from soils of many parts of the United States contained montmorillonite, Ordovician bentonite, and halloysite. Kelley, Dore and Brown (1930) in their extensive chemical and X-ray studies demonstrated with phenomenal clarity and rigor the close relationship between the crystalline character of the constituents of soil clays and their cation exchange properties.…”