E. J. Russell and E. H. Richards 535 



In one important respect these results differ from ours : Sjollema 

 and de Wildt found no more ammouia accumulating at 35° C. than at 

 15° C, while we found notably more at 26° than at 15°. 



The results outlined in the preceding paragraphs are precisely 

 similar to those obtained for sewage, and we have already seen that 

 the same statement holds good for the anaerobic decompositions. 

 There is, therefore, a complete parallel between the decompositions of 

 sewage and of manure. Further, there is a close resemblance between 

 these and the laboratory decomposition of protein. We therefore 

 conclude that the decompositions in all cases start in the same way: 

 under strictly anaerobic conditions they remain the same, but under 

 aerobic conditions further reactions, notably formation of nitrate and 

 loss of nitrogen, set in both in sewage and in manure heaps, which mask 

 the general similarity with the degradation of protein as it has been 

 studied in the laboratory. 



The proof that the missing nitrogen is evolved as gas. 



In all discussions hitherto it has been assumed that the missing 

 nitrogen is evolved as gas, but no definite evidence so far as we know 

 has been adduced in proof. In any experiment on the subject it is 

 obviously necessary that the decomposition should proceed under con- 

 ditions as nearly as possible like those obtaining in nature, and at the 

 same time so rigidly under control that any change in the volume of 

 gaseous nitrogen can be detected. We have succeeded in carrying out 

 the experiment by keeping farmyard manure in a hermetically sealed 

 apparatus so arranged that the air was kept in constant circulation, 

 fresh oxygen introduced whenever necessary, and CO2 removed soon 

 after it was formed. 



The disposition of the apparatus is shown in Fig. 9. A weighed 

 quantity of farmyard manure of known composition was placed in the 

 flask A, connected to an acid bulb B (to absorb ammonia), an alkali 

 bulb C (to absorb QO^)^ and a soda hme tube D, and to the mercury 

 pump E, whereby a stream of air could be drawn through. The pump 

 was so arranged that the whole of the air was delivered back into the 

 flask. The system was closed and it was made rigidly airtight and 

 absolutely beyond any possibility of leakage by building the apparatus 

 up with the aid of the blowpipe and making all the joints of blown 

 glass, and further by having mercury seals on the tap and the flask. 

 A manometer F was attached so that changes in pressure could be read : 

 1 The glass spiral between B and C is to relieve the strain on the apparatus. 



