ABSORBENT POWER OF SOILS. 175 
the absorbent; and in others, as where mordants are used, 
chemical combinations supervene, which possess extraordi- 
nary stability. 
Many facts are known which show that soils, or certain 
of their ingredients, have a fixing power like that of char- 
coal and textile fibers. It is a matter of common expe- 
rience that a few feet or yards of soil intervening between 
a cess-pool or dung-pit, and a well, preserves the latter 
against contamination for a longer or shorter period. 
J. P. Bronner, of Baden, in a treatise on “‘ Grape Cul- 
ture in South Germany,” published in 1836, first mentions 
that dung liquor is deodorized, decolorized, and rendered 
nearly tasteless by filtration through garden earth. Mr. 
Huxtable, of England, made the same observation in 1848, 
and Prof. Way and others have published extended in- 
vestigations on this extremely important subject. 
Prof. Way informs us that he filled a long tube to the 
depth of 18 inches with Mr. Huxtable’s light soil, mixed 
with its own bulk of white sand. “Upon this filter-bed 
a quantity of highly offensive stinking tank water was 
poured, The liquid did not pass for several hours, but 
ultimately more than 1 ounce of it passed quite clear, free 
from smell or taste, except a peculiar earthy smell and 
taste derived from the soil.” Similar results were obtain- 
ed by acting upon putrid human urine, upon the stinking 
water in which flax had been steeped, and upon the water 
of a London sewer. 
Prof. Way found that these effects were not strikingly 
manifested by pure sand, but appeared when clay was 
used. He found that solutions of coloring matters, such 
as logwood, sandal-wood, cochineal, litmus, etce., when fil- 
tered through or siaken up with a portion of clay, are 
entirely deprived of color. (Jour. Roy. Ag. Soc. of 
Fing., XI, p. 364.) 
These effects of clay or clayey matters, like the fixing 
power of cotton and woolen stuffs upon pigments, must 
