Adeney — Dissolved Gases and Fermentative Changes. 619 



3. That with the aid of such observations it is possible to study the various 

 chemical changes which take place progressively during the fermentation within 

 certain well-defined conditions of any fermentable substance or substances, from 

 commencement to completion, at any intermediate step desired. 



4. That it hence becomes possible to demonstrate that the fermentation of 

 substances under aerobic conditions by the organisms usually present in water, 

 takes place progressively in two distinct stages : (1) that in which the organic 

 substances are completely broken down, the carbon and nitrogen being largely 

 converted into carbon dioxide and ammonia, a little organic matter remaining as 

 such, but in an altered form ; and (2) that in which ammonia is oxidized to nitrous 

 or nitric acids, or both. 



5. That the first stage of fermentation must be complete before the second 

 stage can set in. 



6. That the organic substances which result as products of the first stage of 

 fermentation, may undergo further change during the subsequent stage, and give 

 rise to the formation of carbon dioxide, and possibly also to nitric acid. 



7. That peaty matters when present alone in a water undergo very slow 

 change, but when present with ammonium compounds, they readily undergo 

 fermentation together with the ammonium compounds, just as the organic 

 matters, which, as above stated, are formed during the first stage of fermentation 

 of animal, vegetable, or artificial organic substances, do during the after-fermenta- 

 tion of ammonium compounds which may have been also formed thereby, or 

 which may have been previously present or added. 



8. That the presence of the above-mentioned fermented organic matters, or 

 peaty matters, ajjpear to determine the nitric fermentation of ammonia, since in 

 their complete absence, similar organisms being present, only nitrous acid is 

 obtained. 



9. That during the intermediate stages of a fermentation of mixed peaty 

 matters and ammonium compounds, various interchanges between the two appear 

 to take place, the character and extent of which apparently depend upon the 

 relative quantities of peaty matters, ammonia, and dissolved oxygen present, and 

 also upon the character of the peaty matters themselves, whether they have been 

 freshly formed, or have undergone any previous fermentative changes. 



10. That in the presence of small quantities of peaty, or other fermented organic 

 matters, carbon dioxide and ammonia may become "fixed," during fermentation 

 in appreciable quantities, no doubt from Winogradsky's researches to form 

 organic matter. 



11. That the formation of one part by weight of nitrous nitrogen during the 

 fermentation of ammonia, in the complete absence of organic matter, is attended 

 by the consumption of about 4*2 parts by weight of oxygen. 



TEANS. EOT. DUB. SOC, N.S. VOL V., PAET XI. 4 8 



