THE SOUECES OF THE XITEOGEN OF VEGETATION, ETC. 515 



involved. On the other hand, the facts adduced afford a probable explanation of any 

 small loss of Nitrogen which may occur when seeds have not grown, or when leaves, or 

 other dead matter, have suffered partial decomposition. 



F. — The mutual relations of Gaseous Nitrogen and the Nascent Hydrogen evolved during 



the decomposition of organic matter. 



The importance attached by Mulder, and others after him, to the action of nascent 

 hydrogen, evolved in the decomposition of organic matter, upon gaseous Nitrogen, as a 

 source of ammonia, is such as to require that we should refer to the subject here, in 

 the course of the discussion of the conditions possibly affecting the supply of combined 

 Nitrogen to our experimental plants. The results given in the last sub-section (pp. 509- 

 511), leave no doubt of the evolution of hydrogen during the decomposition of organic 

 matter. They suggest, therefore, the possibility that such an evolution may take place 

 in any decomposition of organic matter involved in our experiments on the assimilation 

 of free Nitrogen by plants, and hence prove a source of ammonia to them. 



That nascent hydrogen may, under certain circumstances, combine with gaseous 

 Nitrogen, has long been admitted. But the view so prominently put forth by Mulder*, 

 and some others, that those circumstances occur in the evolution of nascent hydrogen 

 accompanying the decomposition of organic matter, requires confirmation. 



If only a very small part of the hydrogen evolved in the decomposition of organic matter 

 were to form ammonia with the Nitrogen gas which must always be in most intimate con- 

 tact with it, the amount of ammonia formed in this way would be enormous. Peat bogs, 

 cesspools, and all stagnant water pregnant with organic matter, as well as many soils, 

 would be constantly so accumulating ammonia. The extensive forests in different parts 

 of the world, which have been annually depositing a coating of leaves upon the surface 

 of the soil for thousands of years, must also have been a very fertile source of ammonia, 

 as the leaves have gradually decayed under the influence of moisture and confined air 

 beneath the succeeding layers. And when we contemplate the amount of decomposi- 

 tion that must have corresponded to the very exuberant growth of former geological 

 periods, as manifested in the remains exhibited in our coal beds and limestones, we see 

 a source of ammonia, if formed in the manner now under consideration, which would 

 be incalculable. 



The results given in the last subsection (E), upon the decomposition of nitrogenous 

 organic matter, favour the view that the hydrogen evolved in such decomposition does 

 not form ammonia with the Nitrogen of the air. The assumption that it did so, implies 

 that the nascent hydrogen was capable of uniting with free gaseous Nitrogen (forming 

 ammonia) under circumstances in which its affinities were not sufficiently powerful to 

 prevent Nitrogen compounds very similar to ammonias (and which are easily transformed 

 into them) from giving up Nitrogen in the free state. It implies also, that the nascent 

 hydrogen can act upon ordinary Nitrogen, when it cannot do so upon this nascent Nitro- 

 * Chemistry of Vegetable and Animal Physiology, pp. 111-114, 149-152, &c. 



