538 The Storage of Farmuard 3fanure 



This had not sufficed to keep the conditions aerobic and at the end 

 the whole of the oxygen had been used up and 203 c.c. of combustible 

 gas produced. There had, however, been a notable evolution of 

 nitrogen gas, amounting to no less than 121 c.c. Thus the experiment 

 shows that evolution of nitrogen occurred under the mixed aerobic 

 and anaerobic conditions obtaining in the experiment. 



Although the experiment is quantitative in form it is not quantitative 

 in result. The loss of nitrogen in the manure and the gain of nitrogen 

 in the apparatus do not correspond. It could hardly be expected that 

 they should: both are small differences between large figures all of 

 which are liable to some error. 



It will be shown later that the initial and final volumes of nitrogen 

 agreed to within 20 c.c. when analysis of the manure proved that there 

 had been no loss and therefore no evolution of nitrogen : in the 

 experiment now under discussion there had been an increase of 121 c.c, 

 which is therefore far above the experimental error. We may therefore 

 take it that nitrogen is evolved in the gaseous form in the aerobic 

 decomposition of farmyard manure. 



The conditions of aeration were probably not unlike those of the 

 experiments described on p. 533 : and there is a general similarity in 

 the result. But this form of apparatus allows the attainment of much 



