Adeney — Dissolved Gases and Fermentative Changes. 587 



together afford most valuable information, as to the character and quantity of 

 fermentable matters present originally in the respective solutions experimented 

 with. 



Thus, for each solution we have a loss of oxygen determined with great 

 accuracy. That recorded for the solution S3 gives the volume of this gas 

 requii-ed for complete fermentation, while the loss recorded for each of the other 

 two solutions is seen to cover only a partial fermentation of the matters present. 

 The volume of oxygen requu'ed for the comjDlete fermentation of these two 

 solutions could have been determined by additional experiments ; and with 

 the data which would have been thus obtained, we could have contrasted the three 

 solutions as to the total volume of oxygen required for complete fermentation, 

 or, what is of much greater importance, as we have seen already, in the 

 analysis of water polluted with such matters as sewage, we could have distin- 

 guished the volumes of oxygen required for each of the two stages of fermentation 

 in each. 



Fixation of Atmosplieric Nitrogen. 



There are other results which these experimental solutions have furnished, to 

 which the greatest interest will be attached, viz. those afforded by the atmospheric 

 nitrogen determinations. These show that very distinct quantities of that gas 

 were absorbed during fei^mentation in each solution, and they are, so far as I know, 

 the first recorded observations showing dii-ectly that atmospheric nitrogen may be 

 absorbed during bacterial fermentation.* 



On reference to the Table IX. it will be seen that the loss of nitrogen was 

 1'14, 0"94, and 0*88 c.cs., for the three solutions respectively. These numbers 

 are much too high to ascribe to experimental errors, and in proof of this I have 

 appended to the results obtained with the experimental solutions those afforded by 

 samples of the tap-water employed for making the dilutions, which were bottled 

 and kept under exactly similar conditions. 



In reference to these experiments with the tap- water, I may note that they 

 afford additional evidence to that already given, that the minute quantity of peaty 

 matters contained therein really undergo slow fermentation to a degree, which 

 begins to be indicated by the method of observation which I have employed in 

 these experiments, after about four months' keeping. 



* Siace the above was written, M. Winogradsky has published a paper describing the isolation and 

 properties of a butyric ferment, which has the power of fixing free nitrogen. — Arch. Sciences Biol. 1895, 

 3, 297-352 ; also Chem. Soc. Jour. Abstr. 68, 283. 



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



