612 Adeney — Dissolved Gases and Fermentative Changes. 



We have unmistakable evidence in the above results, especially those afforded 

 by the solutions U' and U'/o, that nitrons acid is formed in decided quantity simulta- 

 neously with ammonia, from the very commencement of the fermentation of urea, under 

 aerobic conditions, and in the presence of the mixed organisms of a natural water. 



The results recorded for the solution U' are particularly instructive, because 

 since a small quantity of dissolved oxygen was found in the solution at the 

 conclusion of the experiment, it may be taken for granted that the fermenta- 

 tion therein proceeded throughout its course, so far as it went, under aerobic 

 conditions. 



Under these conditions we find that the nitrous nitrogen formed was 

 practically one-fourth the quantity of ammoniacal nitrogen produced at the 

 same time, the former amounting to O'OOIG grammes, and the latter to 0'006 

 grammes. 



The volume of carbon dioxide, viz. 9 '48 c.cs., equal to O'OOd grammes carbon, 

 which was simultaneously formed with these quantities of nitrous and ammoniacal 

 nitrogen, is not in atomic proportion therewith, but is equivalent, it will be found, 

 to a quantity of carbon much greater than such proportion would allow. It must, 

 therefore, have been derived, in part at least, from some intermolecular changes 

 set ujD in the portion of the urea fermented. If the composition of these bodies, 

 or body, were known, we should then have, with the results recorded in the above 

 Table, all the factors required for the precise formulation of the changes which 

 urea undergoes during fermentation under the conditions given. 



The study of this fermentation of jDure urea by the method here employed 

 became, in fact, of very great interest. To what, for instance, is this formation of 

 the nitrous acid during the first-stage fermentation of urea analogous ? 



Is it analogous to the formation of the same body during true nitrifica- 

 tion ? I am inclined to think not. It is rather, I should say, to be classed 

 with the oxidized organic bodies which we know are formed during the first- 

 stage fermentation of more highly carbonated compounds, the nitrogen in the 

 said nitrous acid substituting carbon, and this being possibly owing to the very 

 small quantity of carbon contained in the urea, and to the chemical characters 

 thereof. Before, however, this and other points suggested by the above experi- 

 ments can be decided, a much more extended investigation will be necessary, and 

 this, I hope, to commence shortly. 



The fermentation in the solution U'/S appears from the results recorded for it, 

 to have proceeded further than in the solution just considered. A larger volume 

 of oxygen was consumed, and a relatively larger quantity of nitrous nitrogen was 

 formed. The carbon dioxide and ammonia were also increased, and in such large 

 proi^ortion that an anaerobic fermentation must, no doubt, have partially set in 

 during tlie experiment. 



