408 
CERAMICS OF GUMBO SOILS 
chemistry was only beginning to reach practical application. 
Schlosing,® as a ceramic chemist, was barely known. He was yet 
too near then to be appreciated. And of course the later and more 
important investigations of Cushman,® a decade after, were not 
thought of. 
It is now a well known fact that the plasticity of lean clays is 
greatly increased by ordinary humus which is essentially an or¬ 
ganic colloid. Clays placed in cool, damp situations are known to 
increase their plasticity in the short span of a few weeks. When so 
placed under proper conditions in nature the soils are termed cold, 
sour or intractible. They are the typical gumbos. But this trans¬ 
formation also takes place often in a few weeks. Soil weathering 
itself is a colloid producing process. 
-In the ceramic industries very plastic clays, even gumbo, are 
easily produced artifically by the very simple means of working in 
small quantities of common colloids. Thus various clays have their 
plasticity raised fifty per cent by the addition of less than one per 
cent of agar-agar. In the same way gumbo may be produced in 
the laboratory in the space of a few minutes from shale, loess, 
lean clay, or almost any soil. 
Cold, plastic soils do not have to be derived from Glacial till 
alone. They do not have to be dubbed gumbotil, because such term 
is clearly indicative of false genisi. They are not measures of 
geological time; they are not time-measures at all. Instead of be¬ 
ing an index of the Glacial advances denoting millions of years, 
gumbo may form under the light of a full moon and the falling 
dews of a single midsummer night. 
With proper tiling or draining the most intractible gumbo patch 
soon loses its characteristic qualities, fails in its identity, and reverts 
again to its primitive state. Alleged weathering transformations 
of a million years vanish in a few weeks. And presto! gumbotil 
again stands forth an old till, a young till, a loess, a stratified silt, 
an alluvium, or what not; whatever the original underlying regolith 
happens to be — indistinguishable, continuous, perfectly unaltered. 
8 Fremy’s Encyc. Chimique, p. 67, 1888. 
9 Trans. American Ceramic Soc., Vol. VI, 1904. 
