Adeney — Dissolved Gases and Fermentative Changes. 573 



It will be observed, on looking over the results given in the two foregoing 

 Tables, that a fermentation of both nitrous acid and ammonia into nitric acid took 

 place in each solution ; that the fermentation of the nitrous acid in solutions 1/2 

 and 1/4 was incomplete, but complete in the remaining solutions, and that the 

 ammonia was not completely oxidized in any of the solutions ; and finally, that a 

 decided quantity of carbon dioxide was formed during fermentation in each 

 solution. This last noted product becomes of interest, and I may say of 

 importance, when considered in relation to the recent researches of Dr. Munro, 

 Professor P. F. Frankland and Mrs. G. C. Frankland, Mr. Warrington, and 

 M. Winogradsky, already referred to, on the nitrification of ammonia in the 

 absence of organic matters. These observers have all shown that the product of 

 fermentation of ammonia in the absence of organic matter is invariably nitrous 

 acid ; and Winogradsky has supplied quantitative proof that the nitrous organism 

 produces organic matters from inorganic materials, about thirty-five parts of 

 nitrogen being oxidized for one part of carbon assimilated from ammonium 

 carbonate. In the above tables we see that the nitric fermentation therein 

 illustrated is accompanied by the formation of very distinct volumes of carbon 

 dioxide, just as was noted in refei'ence to the second experiment recorded in 

 Table III. The question arises, what was the nature of the organic matter from 

 which this gas was derived. 



From the next series of experiments, which I shall have to describe, we shall 

 find evidence which goes to show that the organic matters which undergo change 

 during a second stage fermentation of the character above illustrated, have them- 

 selves been formed during a first stage fermentation under aerobic conditions. 



The results recorded in Table V. for solution 1/4 require special reference, 

 as they appear to be exceptional when compared with those afforded by the 

 other solutions of the series. 



Thus, relatively less carbon dioxide was formed in it ; and the total inorganic 

 nitrogen found after fermentation was decidedly less than that present before 

 fermentation, the quantities being 0.00583 and 0.00670 parts per 1000 

 respectively. On the other hand, the volume of dissolved oxygen actually 

 absorbed was relatively similar to that absorbed in the other solutions. 



The exceptional results here apparent are not, I consider, due to experimental 

 errors ; they are rather to be ascribed to a difference of type, or phase, of a second 

 stage fermentation. 



In the other solutions of this series we have apparently one and the same type 

 of nitrogen fermentation taking place, viz. a fermentation of NH3 and N2O3 into 

 N2O5, accompanied by a fermentation of organic matter. In the solution under 

 discussion we have also this type of fermentation occurring, but, apparently, 

 in addition, another type, viz. the oxidation of ammonia, and possibly also of 



4 M2 



