552 



cases, to more than 1 2 per cent, of the original nitrogen of the sub- 

 stance. 



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, arid 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 

 pure 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, no free nitrogen was 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 

 question of assimilation, however, but a very small proportion of the 

 total organic matter is submitted to decomposing actions apart from 

 those associated with growth, and this for a comparatively short 

 period of time, at the termination of which the organic form is 

 retained, and therefore but very little carbon is lost. It would 



