572 



Adeney — Dissolved Gases and Fermentative Changes. 



On multiplying each set of differences, so as to make them comparable one 

 to another, and to the undiluted sample, we get : — 



Table VI. 



In the results given in these two Tables we have still further evidence that 

 the volume of oxygen absorbed is practically proportional to the quantity of 

 matters fermented ; but in them we have also a more definite indication of the 

 chemistry of at least one phase of nitrification than is observable in those of the 

 two preceding series of experiments. 



It may be taken for granted, I think, from the fact that nitrification had 

 already been well established in this sample of filtered sewage-water before the 

 commencement of my experiments, and from the general character of the results 

 obtained, that the first stage of fermentation had been completed dm-ing the 

 process of filtration to which it had been subjected at the Works from which it 

 had been collected. 



We have therefore in this series of experiments illustrations of the second 

 stage of fermentation or true nitrification only ; and it fortunately happens that the 

 dilutions made up Avere just of sufficient strength to clearly illustrate the chemical 

 changes which accompany nitric fermentation in jjolluted waters during their 

 passage through land or artificial filters. 



* The numtcrs in this column have been calculated on the assumption that N as NaOj, shown to haye 

 been lost during fennentation, was completely oxidized to N2O5 ; and the figures in the next column have 

 been calculated on the assumption that the oxidation of the N2O3 took place according to the equation 



N2O3 + 02 = N2O5. 



This gives 08 c.cs. oxygen required to oxidize 0-001 grammes N as N2O3 to K2O5. 



f The numbers in this column give the IS^O^ less the loss of N2O3 during fermentation, and it is 

 assumed that these quantities were derived from ammonia. The numbers in the next column have been 

 calculated on this assumption, as already explained. These four columns have been added simply for the 

 purpose of approximate comparison. 



It will be obseiTed that the total N as NH3 and N2O3 lost in the case of each Bolution, except 

 solution 1/4, is nearly equal in quantity to the N as NjOa formed. 



