THE SOURCES OF THE NITROGEN OF VEGETATION, ETC. 511 
Taste X.—Showing the products of the action of the reducing forces exercised in the 
decomposition of Nitrogenous organic matter, as exhibited by the composition of 
the gases evolved. 
Composition of the Gas, Per Cent. 
Description of Organic matter subjected ae pe 
to Dechmpostaan: eoe™ "Carbonic acid. Hydrogen. Nitrogen. 
cub. cent. 6 
4°87 34°83 0:30 
a. Wheat, Barley, and Bean seed ...| 400 6454 35°46 traces. 
6. Turnip plant; root with leaves ...| 166-2 76°23 22-91 0-87 
e. Turnip plant; root with leaves ...| 162*2 68-83 23:93 7°24 
er : 68-06 25°63 6°31 
d. Turnip plant; root with leaves ...| 123°6 67-52 25-43 7605 
e. Turnip plant; root with leaves ...} 41-2 64:95 14-66 20°39 
The first experiment (a) is that which has been considered above. In all the other 
cases about two ounces of young Turnip Plant, the root and leaves together, were 
operated upon. They were exposed in similar vessels to those used in the other expe- 
riments, from August 29 to October 5. At the termination of this period the structure 
of the plant was almost entirely destroyed; and there remained only a mass of decom- 
posed matter deposited at the bottom of the vessels. The evolution of gas had entirely 
ceased. 
The Turnip plant (6) was exhausted of its gas before exposure; and, as will be seen, 
there was, under these circumstances, a very small quantity of free Nitrogen found at 
the termination of the experiment. 
All the other Turnip plants were submitted to decomposition without previous 
exhaustion; and hence the amount of Nitrogen eventually found. In the last experi- 
ment (¢) there is a much larger percentage of Nitrogen than in the other cases. But 
the total quantity of gas was much less; and the comparison of this result with the 
others shows that there was an almost constant actual quantity of Nitrogen in the 
several cases, doubtless due to that existing within the plant at the commencement of 
the experiment. Hence it appears that, in the absence of free oxygen, no free Nitrogen 
is evolved from the nitrogenous compounds of the plant. 
At all events the entire cessation of the evolution of gas after the decomposition has 
gone on for a few days, shows that the presence of free oxygen is essential to the evolu- 
tion of Nitrogen, as it is conducive to that of carbonic acid. The loss of Nitrogen 
indicated in Tables VII. and IX. must be considered, therefore, to be the result of an 
oxidizing process. 
We shall have to allude again to the results given in Table X. when we come to dis- 
cuss the question of the formation of ammonia from the free Nitrogen of the air, and 
the nascent hydrogen evolved during the decomposition of organic matter. 
In order to examine the character of the decomposition of organic matter in oxygen 
gas, an investigation was undertaken, which, owing to the difficulty of getting the requi- 
MDCCCLXI. 4a 
