THE AMMONIA OF THE SOIL. 241 
in fertile soils substances which combine chemically with 
ammonia. 
That the soil does contain a certain quantity of ammo- 
nia adhering to the surface of its particles, or, more prob- 
ably, dissolved in the hygroscopic water, is demonstrated 
“by the experiments of Boussingault and Lewy just alluded 
to, in all of which ammonia was detected in the air in- 
cluded in the cavities of the soil. In case ammonia were 
physically condensed or absorbed, a portion of it would 
be carried off in a current of air in the conditions of 
Boussingault and Lewy’s experiments,—nay, all of it 
would be removed by such treatment sufficiently prolonged. 
Brustlein (Boussingault’s Agronomie, etc., 1, p. 152) 
records that 100 parts of moist earth placed in a vessel of 
about 24 quarts capacity containing 0.9 parts of (free) 
ammonia, absorbed during 3 hours a little more than 0.4 
parts of the latter. In another trial. 100 parts of the same 
earth dried, placed under the same circumstances, absorb- 
ed 0.28 parts of ammonia and 2.6 parts of water. 
Brustlein found that soil placed in a confined atmos- 
phere containing very limited quantities of ammonia can- 
not condense the latter completely. In an experiment 
similar to those just described, 100 parts of earth (tena- 
cious calcareous clay) and 0.019 parts of ammonia were 
left together 5 days. At the conclusion of this period 
0.016 parts of the latter had been taken up by the earth. 
The remainder was found to be dissolved in the water 
that had evaporated from the soil, and that formed a dew 
on the interior of the glass vessel. 
Brustlein proved further that while air may be almost 
entirely deprived of its ammonia by traversing a long 
column of soil, so the soil that has absorbed ammonia 
readily gives up a large share of it to a stream of pure air. 
He caused air, charged with ammonia gas by being made 
to bubble through water of ammonia, to traverse a tube 1 
ft. long filled with small fragments of moist soil. The 
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