THE NITRIC ACID OF THE SOIL. 261 
lost during three summer montlis eight-tenths of one per 
cent of carbon. In the numerous similar experiments 
made by Boussingault with soils destitute of organic mat- 
ter, no accumulation of nitrogen occurred beyond the 
merest traces coming from condensation of atmospheric 
ammonia. 
Certain experiments executed by Mulder more than 20 
years ago (Chemistry of Animal and Vegetable Physi- 
ology, p. 673) confirm the view we have taken. Two of 
these were ‘‘made with beans which had germinated in 
an atmosphere void of ammonia, and grown, in one case, 
in ulmic acid prepared from sugar, and also free from am- 
monia; and, in the other case, in charcoal, both being 
moistened with distilled water free from ammonia, The 
ulmic acid and the charcoal were severally mixed up with 
1 per cent of wood ashes, to supply the plants with ash- 
ingredients. I determined the proportion of nitrogen in 
three beans, and also in the plants that were produced by 
three other beans. The results are as follows :— 
Whéte beans in ulmic acid. Brown beans in charcod. 
Weight. Nitrogen. Weight. Nitrogen. 
Beans, 1.465 grm. 50 cub. cent. 1.27¢7 27 cub. cent. 
Plants, 4.167, * 160.2" *f gre ae wh 
The white beans, therefore, whilst growing into plants 
in substances and an atmosphere, both of which were fiee 
of ammonia, had obtained more than thrice the quantity 
of nitrogen that originally existed in the beans; in thie 
brown beans the original quantity was doubled.” Mulder 
believed this experiment to furnish evidence that ammonia 
is produced by the union of atmospheric nitrogen with 
hydrogen set free in the decay of organic matters. To 
this notion allusion has been already made, and the con- 
viction expressed that no proof can be adduced in its 
favor (p. 239). The results of the experiments are fully 
explained by assuming that nitrogen was oxidized in nitri- 
fication, and no other explanation yet proposed accords 
with existing facts. 
