DECAY OF NITROGENOUS BODIES. 291 
in absence of free oxygen may remove this element from 
reducible bodies (Traube, Fermentwirkungen, pp. 63-78). 
In a mixture of cellulose, sugar, and albuminoids, ere- 
mecausis, fermentation, and putrefaction, may all proceed 
simultaneously. 
When the albuminoids decay in the soil associated with 
carbohydrates and humus, the final results of their altera- 
tion may be summed up as follows: 
1. Carbon unites mainly with oxygen, forming carbonic 
acid gas, which escapes into the atmosphere. With im- 
perfect supplies of oxygen, as when submerged in water, 
carbonic oxide (CO) and marsh gas (CH,) are formed. A 
portion of carbon remains as humus. 
2. Hydrogen, for the most part, combines with oxygen, 
yielding water. In deficiency of oxygen, some hydrogen 
escapes as 1 carbon compound (marsh-gas), or in the free 
state. If humus remains, hydrogen is one of its con- 
stituents. 
3. a. Nitrogen always unites to a large extent with 
hydrogen, giving ammonia, which escapes as gaseous car- 
pbonate in considerable quantity, unless from presence of 
carbohydrates much humus is formed, in which case it 
may be nearly or entirely retained by the latter. Lawes, 
Gilbert, and Pugh, (Pz. Trans. 1861, IL, p. 501) made 
observations on the decay of wheat, barley, and bean 
seeds, either entire or in form of meal, mixed with a large 
quantity of soil or powdered pumice, and exposed in vari- 
ous conditions of moisture to a current of air for six 
months, They found in nine experiments that from 11 to 
58°|, of the nitrogen was converted into ammonia, al- 
though but a trifling proportion of this (on the average 
but 0.4°|,) escaped in the gaseous form. 
b. In presence of excess of oxygen, a portion of nitro- 
gen usually escapes in the free state. Reiset proved the 
escape of free nitrogen from fermenting dung. Boussin- 
