138 
Liquid Manure. 
The preceding analytical results suggest the following re- 
marks : — 
1. It will be noticed that liquid manure in contact with soil 
parts with a considerable quantity of ammonia, which, in some 
form or the other, is taken up by the soil. In this experiment 
soil and liquid manure were employed in the proportion of 2 
of soil to 7 of liquid. A gallon of liquid manure in this experi- 
ment yielded to 20,000 grains of soil 14*77 grains of ammonia ; 
accordingly, 1000 grains of soil absorbed 738 grains of ammonia. 
Whether this is the maximum proportion of ammonia which 
this soil is capable of absorbing, or whether it would have taken 
up more or less ammonia when mixed with liquid manure in a 
different proportion than in the experiment, I am unable to tell 
for the present. It appears to me, however, probable that the con- 
centration of the liquid in some measure determines the amount 
of ammonia which is retained by the soil. 
Referring to a previous experiment with drainings of dung- 
heaps. I find that 11,000 grains of a similar soil to the one from 
field Xo. 19 absorbed only "365 grains of ammonia, or about 
half the quantity. These drainings of a dungheap originally con- 
tained 19 68 grains of ammonia to the gallon, and after filtration 
through soil 6 91 grains. 
Further experiments with different descriptions of ammo- 
niacal manuring matters and the same kind of soil are necessary 
before it can be decided whether the quantity of ammonia ab- 
sorbed by a particular soil is constant, or whether it is influenced 
by the concentration or chemical composition of the manuring 
liquids with which the soil is brought into contact. 
2. The amount of organic matter in the liquid manure em- 
ployed in the experiment was less before than after filtration 
through the soil. Pure distilled water left in contact with 
arable land, I have shown before, extracts a considerable propor- 
tion of organic matter from the latter ; and as the liquid manure 
originally contained but little, it need not cause surprise that it 
dissolved more when brought into contact with a soil containing 
a fair proportion of decomposed vegetable remains. The in- 
crease in organic matter accounts for tlie somewhat larger pro- 
portion of nitrogen in the organic portion of the filtered liquid. 
3. On the other hand, the total quantity of mineral matter in 
the liquid manure after digestion with the soil has diminished in 
about the same proportion in which that of organic matter has 
increased. 
4. It is worthy of notice that the liquid manure originally con- 
tained no oxide of iron. Left in contact with soil it dissolved 
2 55 grains per gallon. The liquid analysed was ]>erfect 1 1/ dear, 
and the oxide of iron found cannot, therefore, arise from any 
suspended particles of soil. 1 have, moreover, repeated the 
