AQUEOUS SOLUTION OF THE SOIL. 323 
Mode whereby dilute solutions may nourish Crops.— 
There are other considerations which may enable us to 
reconcile extreme dilution of the nutritive liquid of the 
soil, with the conveyance by it into the plant of the req- 
uisite quantity of its appropriate food. It is certain 
that the amount of matters found in solution at any 
given moment in the water of the soil by no means repre- 
sents its power of supplying nourishment to vegetation, 
If the water which has saturated itself with the solu- 
ble matters of the soil be deprived of a portion or all of 
these matters, as it might be by the absorptive action of 
the roots of a plant, the water would immediately act 
anew upon the soil, and in time would dissolve another 
similar quantity of the same substance or substances, and 
these being taken up by plants, it would again dissolve 
more, and so on as long and to such an extent as the soil 
itself would admit. In other words, the same water may 
act over and over again in the soil, to transfer from it to 
the crop the needful soluble matters. It has been shown 
that the substances dissolved in water may diffuse through 
animal and vegetable tissues independently of each other, 
and independently of the water itself. (H.C. G., p. 340.) 
Deportment of the Soil to renewed portions of Water. 
—It remains to satisfy ourselves that the soil is capable 
of yielding soluble matters continuously to renewed por- 
tions of water. The only observations on this point that 
the writer is acquainted with are those made by Schulze 
and Ulbricht. Schulze experimented on a rich soil from 
Goldberg, in Mecklenburg ( Vs. S¢., VI., 411). This soil, 
in a quantity of 1,000 grams (= 2.2 lbs.) was slowly 
leached with pure water, so that one liter (= 1.056 quart) 
of liquid passed it in 24 hours. The extraction was con- 
tinued during six successive days, and each portion was 
separately examined for total matters dissolved, and for 
~ phosphoric acid, which is, in general, the least soluble of 
the soil-ingredients. 
