600 Adeney — Dissolved Gases and Fermentative Changes. 



formed, 0'0033 grammes; no carbon dioxide was formed dui-ing this stage of 

 fermentation, but, on the contrary, 0'56 c.cs. were fixed. 



The volume of oxygen theoretically equivalent to the nitric nitrogen formed, 

 viz. 0"0033 grammes is 10"53 c.cs., a volume tliis time much in excess of that 

 actually consumed. It would seem from the last observation that an interchange 

 between the jieaty matters and ammonia took place during this step of the 

 fermentation, but no doubt of a different character, notwithstanding the fact that 

 carbon dioxide was fixed rather than formed. It is perhaps right to mention that 

 all the determinations given in this Table, and in the preceeding one, were made 

 with extreme care, all being checked by duplicate analyses, and in the case of 

 many of the nitrogen determinations by triplicate analyses, and further that some 

 of the nitric nitrogen determinations were confirmed by Crum's method with 

 Lunge's nitrometer. 



Experiment 4 demonstrates another pliase of interchange between the two 

 bodies, and it must be noted of nitrous acid, during fermentation, thus the quanti- 

 ties of oxygen and ammoniacal and nitrous nitrogen taken up were, respectively, 

 6'35 c. cs., 0*0022 grammes, and 0'0016 grammes, and of carbon dioxide and 

 nitric nitrogen formed, 1*07 cc. and 0"0025 grammes. The volume of oxygen 

 theoretically equivalent to this last-mentioned quantity of nitric nitrogen, supposing 

 part of it was derived from the O'OOIG grammes of nitrous nitrogen taken up and 

 the rest from ammoniacal nitrogen, is 4 '15 c.cs., a volume less again than that 

 consumed. 



In the last experiment with PA/3, we find a still further phase of interchange 

 during fermentation demonstrated, the quantities of oxygen and ammoniacal 

 nitrogen shown by this experiment as being taken up, and of nitrous and nitric 

 nitrogen formed being, respectively, 6'55 c.cs., 0"001 grammes, 0*77 c.cs., 0*0026 

 grammes, and O'OOIS grammes. Tlie total quantity of nitrous and nitric nitrogen 

 formed was thus equal to 0*0044 grammes, a quantity largely in excess of the 

 ammoniacal nitrogen taken up. The total volume of oxygen theoretically 

 equivalent to the nitrous and nitric nitrogen formed, assuming that both were 

 derived from the ammoniacal nitrogen, is 11 "96 ccs. There can, therefore, be 

 little doubt from these results that the nitrous and nitric nitrogen formed during 

 this last step of the fermentation, represented by experiment 5, were derived from 

 compounds resulting from the interchanges which, we have seen, must have 

 occui-red between the peaty matters and ammonia present in the water during 

 the earlier steps of the fermentation. 



It must be remembered in reference to this point, that the organic nitrogen 

 actually present in combination with the peaty matters in the solution PA/3 

 at the time these experiments were commenced was only 0*00133 grammes. If 

 we sum together the quantities of ammoniacal nitrogen absorbed, and of the 



