Power of Soils to Absorb Moisture. 71 
moisture are considered: — 1. Peat, or pure organic matter. 2. 
Marl — or, to be explicit and definite — fresh water and shell marL 
3. Clay, and argillaceous compounds in which this element is in 
excess. 4. Loam, or the common soils as they usually occur. 
5. Sandy loam. 6. Sand. Each of these kinds of earth is influ- 
enced in its power of absorbing and retaining moisture, by the 
amount of peaty matter which it contains, subject to modification 
by its fineness." 
The quantity of water soils are susceptible of taking up. — Now 
we will endeavor to show that the absorbing and retaining powers 
of soils are as the quantity of water which they are susceptible of 
taking up. The experiments to prove this were conducted in the 
following manner : — A quantity of each soil to be examined was 
taken, and water added as long as it would be absorbed; then a 
portion of each, saturated with moisture, was weighed. Those 
which were suspected to contain water chemically combined were 
dried at 212°; others, as the sands, were dried on a sand bath at 
a higher temperature. After drying, they were weighed, and the 
loss set down as the amount of water they were susceptible of 
taking up. 
"We do not offer these as strictly accurate results; yet they are 
sufficiently so for the purpose in this place, and more accurate, 
perhaps, than would be supposed from the manner in which they 
were made. AVe were surprised on testing the quantity of water 
several times in succession, which the same soil would take up, to 
find so slight a variation in the results. After a soil is saturated, 
it requires but a very slight quantity more of water to render 
sensible the free moisture. Hence, by using care, we think that 
results may be arrived at, which if not strictly accurate, may be 
of great practical value. It is no trifling matter to determine 
with any degree of accuracy the absorbing and retaining power 
of soils directly, by evaporation, so that the results of observations 
on the same soil made at different times, shall agree, since the 
quantity of moisture in the atmosphere has to be determined at 
aecb observation. Even if it was not very diflScult, those who 
