Adeney — Dissolved Gases and Fermentative Changes. 579 



renders it possible, it will be seen, to examine the intermediate steps of both the 

 first and the second stage fermentations, and to obtain important results. 



To confine attention, in the first instance, to the intermediate steps of the first- 

 stage fermentation recorded in experiments 1, 2, 3, and 4, in Table VII., we 

 notice that during the steps represented by the first three experiments much 

 larger volumes of carbon dioxide were formed than could be accounted for on the 

 assumption that the fermentation in each case consisted of a simple oxidation 

 effected through the agency of the active organisms present in the solution, upon 

 a quantity of the organic matters equivalent to the volume of dissolved oxygen 

 absorbed. Thus, the calculated ratio of carbon dioxide formed to that of the 

 oxygen absorbed by the complete oxidation of the asparagine to carbon dioxide, 

 water, and ammonia, and of potassium sodium tartrate, to its ultimate products 

 of oxidation, are, respectively, as l"33 : 1, and TG ; 1, and if equivalent proportions 

 of these two substances be oxidized at the same time, then the ratio becomes 

 I "465 : 1. On the other hand the ratios of the volumes of carbon dioxide actually 

 formed to those of oxygen absorbed, in experiments 1, 2, and 3, are as 2 : 1, r85 : 

 1, and 1"86 : 1, respectively. While for experiment 4 this ratio drops nearly to 

 1:1. 



It is quite evident, therefore, that, notwithstanding the fact that the earlier steps 

 of the first stage fermentation represented by experiments 1, 2, and 3, were 

 attended throughout with aerobic conditions, changes other than those which 

 would result from simple oxidation by the dissolved oxygen absorbed, must have 

 been set up in the organic matters present in the solution. These changes seem to 

 have been complete by the end of the step represented by experiment 3, for the 

 ratio of carbon dioxide formed to oxygen absorbed during the next stage 

 represented by experiment 4, drops suddenly to 1:1. 



This ratio is so low that we are justified in believing that the organic matters 

 which underwent fermentation during this last step were not uufermented portions 

 of the matters originally present, but were themselves the products of the changes 

 which we have seen must have been set up during the earlier steps of fermentation 

 represented by experiments 1, 2, and 3. 



In experiment 5 it appears we have illustrated the completion of the first-stage 

 fermentation, and the commencement of the second stage. Judging from the 

 quantities of carbon dioxide, ammonia, and nitrous acid formed, and oxygen 

 absorbed, it is probable that nearly the whole of the first-named product should 

 be referred to the first stage. Thus the volume of oxygen theoretically 

 required to oxidize 0'0015 grammes nitrogen as ammonia to nitrous acid equals 

 3"585 CCS. Deducting this from the volume of oxygen shown by the experiment 

 to have been absorbed, we get 3"455 c.cs., while the volume of carbon dioxide 

 formed was 3 '8 c.cs. These volumes approach sufficiently near in proportion to 



IKANS. EOY. DUB. SOC, N.S. VOL. V., PAKT XI. 4 N 



