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AQUEOUS SOLUTION OF THE SOIL. 321 
solution was diminished either by reducing the proportion 
of solid matters below 0.5, or increasing it to 2 parts in 
1,000 of water. The proper dilution of the food of plants 
for most vigorous growth and most perfect development 
is thus approximately indicated. 
_We notice, however, considerable latitude as regards 
the proportions of some of the most important ingredients 
which are usually present in least quantity in the aqueous 
solution of the soil. Thus, phosphoric acid in one case is 
thrice as abundant as in the other. We infer, therefore, 
that the minimum limit of the individual ingredients is 
not fixed by the above experiments, especially not for or- 
dinary growth. 
Birner and Lucanus communicate other results ( Vs. S¢., 
VIIL, p. 154), which throw much light on the question un- 
der discussion. They compared the growth of the oat plant, 
when nourished respectively by a rich garden soil, by 
ordinary cultivated land, by a solution the composition 
of which is given above, and lastly by a natural aqueous 
solution of soil, viz., a well-water. Below is a statement 
of the weight in grams of an average plant, produced in 
these various media, as well as that of the grain yielded 
by it. 
Dry crops compared 
Weight of aver- Weight of with seed, the latter 
age plant, dry. dry Grain. taken as unity. 
Carmen. ov. 5. 3. 5.27 1.23 193 
Vl: ae 1.75 0.63 64 
Este) | 3.75 1.53 137 
Well-water....... 2.91 1.25 106 
We gather from the above figures that well-water, in 
quantities of one quart for each plant, renewed weekly, 
gave a considerably heavier plant, straw, and grain, than 
a field under ordinary culture ; the yield in grain being 
double that of the latter, and equal to that obtained in a 
rich garden soil. 
14* 
