E. J. Russell and E. H. Richards 497 



amino-acids, followed by a splitting off of ammonia from the amino- 

 acids. But in the manure heaps, as already stated, ammonia does 

 not accumulate, and there is nothing to show whether the decomposition 

 proceeds in the same manner as in these cases, or on wholly different 

 lines; 



As a manure heap is rather a cumbersome subject the experiments 

 designed to elucidate this point were made in the laboratory under 

 conditions as nearly as possible similar to those obtaining in the heap. 

 It was found that the decomposition proceeded normally, and ammonia 

 accumulated just as in putrefaction, in sewage decompositions, etc. 



It appears, therefore, that the decomposition of nitrogen compounds 

 in manure follows the ordinary course, giving rise to ammonia, with 

 amino-acids presumably as the intermediate product, but that the 

 decomposition in the heap is masked by two actions : the non-accumula- 

 tion of ammonia, and the loss of nitrogen. 



Experiments showed that ammonia might be lost by direct volati- 

 lisation, by conversion under certain definite conditions into nitrate, 

 or to a small extent by reconversion into complex nitrogen compounds. 

 Of these the two former are known to proceed in sewage decompositions, 

 but the latter has, so far as we know, only been studied in connection 

 with the manure heap. 



The loss of nitrogen cannot be wholly explained by the volatilisation 

 of ammonia. Under laboratory conditions only little volatilisation 

 takes place, and in any cas€ the ammonia is caught in acid traps. Yet 

 there still remains a substantial loss,— 15 %, or more, of the total 

 nitrogen, — which cannot be accounted for. We have been able to show 

 that there is an evolution of gaseous nitrogen during the decomposition, 

 which thus completes the account of the loss. This loss does not go 

 on under anaerobic conditions ; the complex compounds break down, 

 yielding an equivalent amount of ammonia. A similar result has been 

 obtained in sewage decompositions. The loss, therefore, is not caused 

 by a simple reduction of some compound in the manure ; e.g. it is not 

 a simple denitrification. 



Nor does it go on under wholly aerobic conditions ; here again the 

 yield of ammonia phis nitrate is quantitatively equivalent to that of the 

 complex nitrogen compounds broken down. Even when nitrification 

 proceeded vigorously there was still no loss of nitrogen. The loss, 

 therefore, does not arise from a simple oxidation. 



The loss goes on only under the mixed aerobic and anaerobic con- 

 ditions which arise when actual manure, trampled, mixed and compacted 



