Adeney — Dissolved Gases and Fermentative Changes. 609 



Referring now to the experiment (3) with potassium nitrite, it will be seen 

 that as in the case of experiment (2) with ammonia and a portion of the same 

 solution of peat, no carbon dioxide was either formed or fixed, so far as analysis 

 could detect. The volume of oxygen tlieoretically required to oxidize the 

 quantity of nitrous nitrogen which was converted during fermentation to nitric 

 acid, viz. 0-0139 grammes, is 11-12 c.cs., a volume much in excess of that actually 

 consumed (6-72 c.cs.) 



It is impossible to suppose that this large excess of oxygen was derived from the 

 quantity of peat present. Possibly intermediate combinations were formed during 

 fermentation between the peaty matters and the nitrous acid, and that part at least 

 of the nitric acid found after fermentation was formed from these combinations. 



Unfortunately I have not yet been able to determine the relationship between 

 the oxygen consumed and the nitrous nitrogen oxidized during this fermentation 

 of nitrites in purely inorganic solution, a fermentation which Warrington has 

 shown to be possible, by conclusively proving that nitric organisms develop in 

 solutions containing nitrites and the necessary inorganic salts only.* Winogradsk}^, 

 it should be observed, has confirmed this. I trust, however, in a future communi- 

 cation to give the results of some experiments I have already commenced with a 

 view of determining this point, together with the results of a further study on 

 the fermentation of peaty matter and ammonia, upon whicli I am at present 

 engaged, with the object of completing the work of which the experiments I have 

 given can only be regarded as forming the commencement. 



Before concluding my references to the experiments recorded in Table XVI., 

 I should like to draw attention to the results from experiment 2, as compared 

 with those afforded by experiment 1 a, and recorded in Table XV. Those of the 

 former experiment show an almost pure nitric fermentation, unaccompanied by 

 either the formation or fixation of carbon dioxide, while those of the latter 

 experiment show that the fermentation was a purely nitrous one, accompanied by 

 the formation of a large volume of carbon dioxide. And yet in both dilute 

 solutions of peat were employed, and each contained a decided excess of ammonia 

 after fermentation. There was, however, one distinct difference between the two 

 solutions. The peat solution employed for the experiment recorded in Table 

 XVI. had undergone several stages of fermentation before being employed for 

 this experiment, while the solution of peat employed for the other was a 

 comparatively fresh one. We may therefore add an additional conclusion to 

 those already drawn, viz. that the changes which peaty matters may undergo in 

 the presence of decided quantities of ammonia, during fermentation may vary 

 with their nature, i. e. whether they have themselves undergone fermentation 

 previously or not (see p. 604), 



* Warrington : " Eesearches on Nitrification, C.S.J., vol. lix., p. 519. 



