356 HOW CROPS FEED, 
and on the “ Changes which Liquid Manure undergoes in 
contact with different Soils of Known Composition” (idem 
XX., 184-57), he found, in seven experiments, that dung 
liquor, after contact with various soils, lost or gained acid 
ingredients, as exhibited by the following figures, in grains 
per gallon: (loss is indicated by —, gain by +): 
1 2. 8 .4. (53900 
Chloride of Potassium —8.81 +9.17 —2.74 +2.14 —2.74 +2.55 —1.10 
Chloride of Sodium...—3.95 —2.43 —7.04 —1.12 —1.10 —1.24 +3.66 —1.89 +19.05 
Sulphuric Acid........ $2.32 —4.21 —1.06 —1.21 —0.27 +1.24 +3.44 +2.26 —0.42 
Bilicie Acid: ob. vs. +1.63 +10.83 —1.64 +0.72 +2.76 —0.11 —0.07 undet. —1.57 
Phosphoric Acid...... — —_ —4,23 —3.09 —2.91 —3.38 —0.13 —8.76 —%.71 
We notice that chlorine was perceptibly retained in 
three instances, while in the other four it was, on the 
whole, dissolved from the soil, Sulphuric acid was re. 
moved from the solution in four instances, and taken up 
by it in three others. In four cases silica was absorbed, 
and in three was dissolved. In his first paper, Professor 
Way recorded similar experiments, one with flax-steep 
liquor and a second with sewage. The results, as regards 
acid ingredients, are included in the above table, A and B, 
where we see that in one case a slight absorption of chlo. 
rine, and in the other of sulphuric acid, occurred. Way, 
however, regards these differences as due to the unavoid. 
able errors of experiment, and it is certain that in Veelck- 
er’s results similar allowance must be made. Neverthe: 
less, these errors can hardly account for the large loss of 
chlorine observed in 1 and 3, or of sulphuric acid in 2. 
Liebig found in his experiments “that a clay or lime- 
soil, poor in organic matter, withdrew from solutiox of 
silicate of potash, both silicic acid and potash, whereas 
one rich in humus extracted the potash, but left the silicic 
acid in solution.” (Compare pp. 171-5.) : 
As regards nitric acid, Knop observed in a single in- 
stance that this body could not be wholly removed by 
water from a soil to which it had been added in known 
quantity. He regards it probable that it was actually 
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