STUDIES IN THE REVERSIBILITY 
OF THE COLLOIDAL CONDITION OF SOILS 
a. B. BEAUMONT 
The early workers in the field of colloid chemistry considered substances 
possessing colloidal properties to be distinct chemical individuals. Those 
working with scil problems spoke of certain inorganic and organic colloids. 
The colloids found, and thought to exist, in the soil were few in number. 
Colloidal silica, alumina, and ferric oxide among the inorganic compounds, 
and the various organic substances commonly designated as humus, are 
the most frequently mentioned in the Hterature. Additions have been 
made to this list from time to time, and occasionally sharp controversies 
have arisen as to whether the substance in question exists in the soil as a 
_erystalloid or as a colloid. The contradictory results in many cases 
probably can be accounted for by the different geological conditions under 
which the soils studied have been formed. 
The modern conception, as expressed by leading writers on the subject, 
is that colloids are to be considered as a state or condition of matter, not 
as chemical individuals. It has, of course, been long recognized that 
some few substances —for example, silica — exist both as crystalloids 
and as colloids. But recent investigations of Von Weimarn and others 
have so increased the number of substances that have been prepared in 
the colloidal conditions, as to lead some to believe that nearly all sub- 
stances can exist as colloids as well as crystalloids; and Von Weimarn 
(quoted by Ostwald, 1915 :101) has gone so far as to proclaim that “the 
colloid, like the crystalloid, is a universally possible state of matter.” 
It was in accordance with this modern conception of colloidality that 
the work herein described was undertaken, and the data presented show 
that the colloidal condition of the soils worked with is dependent, in a 
degree at least, upon circumstances and environment. The object of the 
work undertaken was to throw some light on the physical changes, and 
their effects, which a soil undergoes with variations in its moisture con- 
tent, especially on being wetted and dried. As is shown later, the prob- 
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