Adeney — Dissolved Gases and Fermentative Changes. 563 



PART I. 



Experiments with easily Fermentable Matters. 



As I have already explained when describing the method of experimenting 

 adopted, the experiments which I have now to record have for the most part been 

 carried out with sets or series of dilutions, varying in strength, of comparatively 

 strong solutions of polluted waters, such as sewage-water, or of other fermentable 

 substances, including those which ferment with ease, and those which ferment 

 with difficulty. 



The details and results of the experiments are given in full in Tables, a 

 separate Table to each set or series of experiments. Each Table, therefore, 

 furnishes a fairly comjjlete view of the nature and amount of the chief substances 

 produced by the action of the mixed organisms natural to the solution or dilution 

 during a fermentaton, carried on under conditions varying within narrow and 

 well-defined limits, as well as the quantity of oxygen consumed in the process. 



The information given in these Tables will, therefore, be found sufficiently full 

 to render them self-explanatory. 



But it will be necessary to discuss the results in some of the Tables at some 

 length in order to indicate the typical results, which the method of experimenting 

 employed can afford, and the general conclusions which can be drawn therefrom. 

 The remaining Tables will be found to furnish additional experimental results, all 

 tending to confirm those specially referred to. 



It will be convenient to discuss, in the first place, the experiments with easily 

 fermentable organic matters ; and this I now propose to do, not necessarily in 

 chronological order, but as they best illustrate the points which have to be 

 considered. 



My first definite series of experiments was commenced on November 5th, 1891, 

 and they were made with a sample of raw sewage collected from a main sewer at 

 Monkstown, a residental suburb of Dublin. The sample of sewage was filtered 

 through ordinary filter-paper to separate the matters in suspension as much as 

 possible, and aerated, and the following dilutions were made from it with 

 tap-water: — one volume of filtered sewage to 9, 19, 29, 39, 49, 59, 69, 79, 89, and 

 99 volumes of tap-water. 



In the following, and all succeeding Tables giving the details and results of 

 experiments, the dissolved gases a,re exj)ressed in c.cs., at 0° C, and 760 mm. bar , 

 and the inorganic nitrogen in fractions of a gramme, per 100 ccs., of solution. 



Under the columns headed I. and II. are given the results of analysis, before 

 and after fermentation, respectively. 



[Table I. 



TEAKS. EOT. BITB., SUC. N.S. VOL. V., PARI XI. 4 L 



