Adeney — Dissolved Gases and Fermentative Changes. 603 



safely take it they do with a fair approximation to the truth, the extent and real 

 nature of the changes which occurred during fermentation in the solution. 



The results recorded for the more dilute solution PA/20, in the first experiment 

 15, are similar in character to those just considered. The volume of carbon 

 dioxide formed, viz. 8'33 c.cs. (equivalent to 0*0045 grammes carbon), shows that 

 the peaty matters must have been nearly completely fermented, as the quantity of 

 carbon present before fermentation was 0*0055 grammes. 



It is interesting to note, further, in reference to the results from both the 

 dilute solutions, that the earlier steps of the fermentation which they underwent 

 were almost entirely nitrous. 



The second experiment, 2h, with the more dilute solution, shows a fixation of 

 carbon dioxide and of ammoniacal or nitrous nitrogen, or both. The oxygen 

 theoretically equivalent to the nitric nitrogen, assuming that it was derived partly 

 from the nitrous nitrogen lost, and the remainder from the ammoniacal nitrogen, 

 is 4 "73 c.cs., while tlie volume actually consumed was 7*2 c.cs. 



General Conclusions from Experiments with Solutions of Peaty Matters 



and Ammonium Compounds. 



On reviewing the evidence afforded by the experiments recorded in Tables 

 XIV. and XV., we may draw tlie following general conclusions as to the various 

 phases of fermentation which may occur in solutions of peaty matters and 

 ammonium compounds, in the presence of the mixed organisms natural to water, 

 under varying conditions of dilution and relative proportions : — 



1. When the proportion of peaty matters present is large, such that the 

 organic carbon amounts to 0*1336 grammes per 1000 c.cs., of solution, and that of 

 ammonium compounds very small (such as 0*0079 grammes nitrogen as ammonia 

 per 1000 CCS.), a fermentation may occur in which tlie ammonia is taken up 

 presumably to form new compounds with the peaty matters, since the nitric acid 

 formed is relatively very small, and since also because very decided volumes of 

 carbon dioxide are evolved. 



The volume of oxygen consumed is decidedly in excess of that theoretically equivalent 

 to the oxidised inorganic products formed during the fermentation. 



2. When the same solution is decreased in strength by dilution, which is equiva- 

 lent to increasing the proportion of oxygen, aU other conditions remaining similar 

 (except of course that of mass), the fermentation may take a different course; the 

 volume of carbon dioxide formed becomes decided, and the ammonia becomes 



TEANS. KOY. DUB. SOC, N.S. VOL V., PART XI. 4Q 



