312 HOW CROPS FEED. 
The foregoing analyses (all the author has access to 
that are sufficiently detailed for the purpose) indicate 
1. That the quantity of soluble matters is greatest—400 
to 1,400 in 100,000—in wet, peaty soils (X, XI, XII), 
though their aqueous solutions are not rich in some of the 
most important kinds of plant-food, as, for example, phos- 
phoric acid. 
2. That poor, sandy soils (VIII, XII) yield to water the 
least amount of soluble matters,—40 to 45 in 100,000. 
3. That very rich soils, and rich soils especially when 
recently and heavily manured as for the hop and beet 
crops (I, II, V, VI, VU, IX, XIV, XV, XVD,, yield, in 
general, to water, a larger proportion of soluble matters 
than poor soils, the quantity ranging in the instances be- 
fore us from 50 to 150 parts in 100,000. 
4, It is seen that in most cases phosphoric acid is not 
present in the aqueous extract in quantity sufficient to be 
estimated; in some instances other substances, as mag- 
nesia, chlorine, and sulphuric acid, occur in traces only. 
5. In a number of cases essential elements of plant- 
food, viz., phosphoric acid and sulphuric acid, are wanting, 
or their presence was overlooked by the analyst. 
Composition of Drain-Water.—Before further discus- 
sion of the above data, additional evidence as to the kind 
and extent of aqueous action on the soil will be adduced, 
The water of rains, falling on the soil and slowly sinking 
through it, forms solutions on the grand scale, the study 
of which must be instructive. Such solutions are easily 
gathered in their full strength from the tiles of thorough 
drained fields, when, after a period of dry weather, a rain- 
fall occurs, sufficient to saturate the ground. 
Dr. E. Wolff, at Moeckern, Saxony, made two analyses 
of the water collected in the middle of May from newly 
laid tiles, when, after a period of no flow, the tiles. had 
