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PHYSICAL CHARACTERS OF THE SOIL. 169 
is absorbed by porous bodies in the largest quantity. 
This not only displaces other gases from their adhesion to 
solid surfaces, but by its own attractions modifies these 
adhesions. 
Reichardt and Blumtritt take no account of water-gas, 
except in the few experiments where the substances were 
purposely moistened. In all their trials, however, moist-_ 
ure was present, and had its quantity been estimated, 
doubtless its influence on the extent and kind of absorp- 
tion would have been strikingly evident throughout. 
Ammonia and carbonate of ammonia in the gaseous 
form are absorbed from the air by the dry soil, to a less 
degree than by a soil that is moist, as will be noticed fully 
hereafter. 
Chemical Action induced by Adhesion.—This physical 
property often leads to remarkable chemical effects; in 
other words, adhesion exalts or brings into play the force 
of affinity. When charcoal absorbs those emanations 
from putrefying animal matters which we scarcely know, 
save by their intolerable odor and poisonous influence, it 
causes at the same time their rapid and complete oxida- 
tion; and hence a piece of tainted meat is sweetened by 
covering it with a thin layer of powdered charcoal. As 
Stenhouse has shown, the carcass of a small animal may 
be kept in a living-room during the hottest weather with- 
out giving off any putrid odor, provided it be surrounded 
on all sides by a layer of powdered charcoal an inch or 
more thick. Thus circumstanced, it simply smells of am- 
monia, and its destructible parts are resolved directly in- 
to water, carbonic acid, free nitrogen, and ammonia, pre- 
cisely as if they were burned in a furnace, and without 
the appearance of any of the effuvium that ordinarily 
arises from decaying flesh. 
The metal platinum exhibits a remarkable condensing 
power, which is manifest even with the polished surface of 
foil or wire; but is most striking when the metal is 
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