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the liquid moves from a small soap-bubble towards a large one, in 
the same way water that surrounds the ground grains moves from 
the fine towards the coarse grains when the state of equilibrium has 
not yet been reached. So far as | know, E. Ramann was the first 
to point out this important influence of the grain-size on the moisture 
of the soil.') In the capillary spaces between the grains the height 
to which the water rises is also in inverse ratio to the cross-section 
of those interstitial spaces. 
Now it seems to me that the same influence manifests itself in 
these phenomena of freezing and thawing of the ground. 
For as soon as the frost penetrates into the ground, the ground 
grains become larger in consequence of their water-envelopes getting 
frozen, and then suck the water to them from the neighbouring, 
still unfrozen grains; this water freezes again, and thus the diameter 
of the solid grains gets greater and greater. In the same way the 
capillary spaces get narrower, so that ground water rises in them. 
The quantities of water that thus can be retained in the frozen 
parts of the ground, must be very considerable. 
This appears in thawing weather from the muddy state of the 
ground at the surface, which thaws first. When also the lower 
layers are thawed, the water that has risen during the frost, can 
sink away, and return to the ground water. 
Plants are not found uprooted through frost until it thaws. This 
may be explained in this way: when the ground thaws, differences 
of tension arise directed from below upward, through which the 
plants that have not yet firmly taken root, are ejected. 
1) In the third edition of his “Bodenkunde’’, p. 332, (Berlin 1911). 
