On the Sources of the Nitrogen of Vegetation. 527 
Tt is not, indeed, hence inferred that nitric acid could under no 
circumstances be formed through the influence of ozone on certain 
nitrogenous compounds, on ‘nascent nitrogen, on gaseous nitrogen in 
contact with porous and alkaline substances, or even in the atmosphere. 
But, considering the negative result with large quantities of ozonous 
air, acting upon organic matter, soil, &c., in a wide range of circum: 
stances, and for so long a period, it is believed that no error will be 
introduced into the main investigation by the cause referred to. 
Numerous experiments were made to determine whether free ni- 
trogen was evolved during the decomposition of nitrogenous organic 
compounds. 
In the first series of 6 experiments, wheat, barley, and bean-meal 
were respectively mixed with ignited pumice, and ignited soil, and 
submitted for some months to decomposition in a current of air, in such 
manner that any ammonia evolved could be collected and estimated. 
The result was, that, in 5 out of the 6 cases, there was a greater or 
less evolution of free nitrogen—amounting, in two of the cases, to 
more than 12 per cent. of the original nitrogen of the substance. 
The second series consisted of 9 experiments; wheat, barley, and 
beans being again employed, and, as before, either ignited soil or 
pumice used as the matrix. In some cases the seeds were submitted 
to experiment whole, and allowed to grow, and the vegetable matter 
produced permitted to die down and decompose. In other cases, 
the ground seeds, or ‘‘ meals,’ were employed. ‘The conditions of 
moisture were also varied. The experiments were continued through 
several months, when from 60 to 70 per cent. of the carbon had 
disappeared. | 
In 8 out of the 9 experiments, a loss of nitrogen, evolved in the 
free state, was indicated. In most cases, the loss amounted to about 
one-seventh or one-eighth, but in one instance to 40 per cent. of the 
original nitrogen. In all these experiments the decomposition of 
the organic substance was very complete, and the amount of carbon 
lost was comparatively uniform. 
It thus appeared that, under rare circumstances, there might be no 
loss of nitrogen in the decomposition of nitrogenous organic matter; 
but that, under a wide range of circumstances, the loss was very 
considerable—a point, it may be observed, of practical importance in 
the management of the manures of the farm and the stable. | 
Numerous direct experiments showed, that when nitrogenous 
organic matter was submitted to decomposition in water, over mer- 
cury, in the absence of free oxygen, there was no free nitrogen 
evolved. In fact, the evolution in question appeared to be the result 
of an oxidating process. 
Direct experiments also showed, that seeds may be submitted to 
germination and growth, and that nearly the whole of the nitrogen 
may be found in the vegetable matter produced. 
It is observed that, in the cases referred to in which so large an 
evolution of free nitrogen took place, the organic substances were 
submitted to decomposition for several months, during which time 
they lost.two-thirds of-their carbon. In the experiments on the 
