Adeney — Dissolved Gases and Fermentative Changes. 583 



so as to render them comparable to the volume of the same gas evolved by the 

 undilute solution A, are practically equal to one another, and also to the volume 

 evolved during fermentation in the undiluted solution. They are respectively 

 equal to 77, 75, and 75 c.cs. 



With reference to the oxygen absorbed during fermentation, it will be seen 

 that, in experiment 2a, the second stage was complete ; and the total volume of 

 oxygen absorbed during both the two stages, when multiplied by 10 for the purpose 

 already explained, amounts to 85 "3 c.cs. 



In experiment 4ffl the oxidation of the nitrogen was not quite complete. 



If, however, we add to the volume of oxygen given in the above Table, viz. 

 77*2 c.cs., the volume of oxygen theoretically required to oxidize the nitrous acid 

 formed in this experiment to nitric acid, viz. 7'68 c.cs., we get a total volume 

 84 "88 CCS., which approximates to that given for the less dilute solution. 



The experiments with solution A do not, unfortunately, give the means of 

 estimating the oxygen absorbed during the second stage fermentation. 



The carbon, both in the asparagine and tartrate employed in these 

 experiments, was carefully determined by combustion in the ordinary way 

 before commencing these experiments. The total organic nitrogen in solution A 

 was also determined by Kjeldahl's method. 



From these determinations it was found that the organic carbon per litre of 

 solution was as follows : — 



0-066 grammes asparagine = 0'0225 grammes carbon, 1 



> equivalent to 85'37 c.cs. COj. 

 0-141 „ tartrate = 0-0234 „ „ t 



Organic nitrogen =0-0139 ,, per litre of solution. 



As already shown, the volume of carbon dioxide formed by the complete 

 fermentation of these quantities of asparagine and tartrate may be taken as equal 

 to 75 c.cs. 



This volume approximates sufficiently close to 85*37 c.cs., the volume which 

 would be formed by the complete oxidation of similar quantities of the same 

 substances, to warrant us in regarding it for purposes of water analyses, as a 

 quantitative expression of the amount of substances originally present in the 

 water. 



The solutions experimented with contained minute quantities of peaty colouring 

 matters, besides the substances added. These matters, however, probably under- 

 went little, if any, change. 



I may here note that the volume of carbon dioxide formed by the fermentation 

 of the peaty matters in the tap-water employed for making up the dilutions may 

 be taken as about 1 c.c. per litre (see p. 561). 



