598 Adeney — Dissolved Gases and Fermentative Changes. 



Eeferring to Table XIV. we find, from the first experiment, that the first 

 stage fermentation of solution P was not complete at the time of commencing the 

 experiments ; the remaining portions of solution P were in consequence diluted, as 

 described in the Table, with twice their bulk of distilled water, and exposed to the 

 air for a week to allow of its completion. 



From the fact that nitrification had commenced in experiment 2, we may take 

 it that the first-stage fermentation in the solution had been completed. The points 

 most markedly exhibited by experiments 2 and 3 are a formation of carbon dioxide 

 and a loss of oxygen and ammonia. As for the indications of nitrification, they are 

 decided in the former experiment ; but the nitric acid formed was equivalent to 

 only about half the quantity of ammonia absorbed, while in the latter experiment 

 no nitric acid appears to have been formed, although a very decided quantity 

 of ammonia was absorbed. It appears then from these experiments that a 

 fermentation of small quantities of ammonia in the presence of considerable quantities of 

 peaty colouring matters may take place, in such a manner that the ammonia is absorbed, 

 and carbon dioxide is formed, while oxygen is consumed in relatively considerable volumes, 

 but that little or no nitric (no nitrous) acid may be produced. 



In experiment 4 the nitric acid formed is about equivalent to the ammonia 

 absorbed. It is important, however, to note that this last product is the least 

 marked result of the fermentation ; the volume of carbon dioxide formed and 

 oxygen consumed being relatively both very much larger in quantity. 



Experiments 5 and 6 were made with a diluted portion of solution P/3 prepared 

 for experiment 2, and the former of these two experiments was commenced on 

 the same day as the last mentioned. It is possible and interesting, therefore, 

 to compare the results obtained with the less and more dilute solutions P/3 

 and P/9. 



The first result of fermentation shown with bottle I, on June 12th, less than a 

 month afterwards, was the complete fixation of the ammonia, and the formation 

 of a quantity of nitric acid practically equivalent to the ammonia lost, 

 accompanied by the formation of carbon dioxide. 



The results obtained on keeping the other portions of the same solution (in 

 bottles II. and III.) for a further period of about six weeks, were, a further 

 formation of a decided quantity of carbon dioxide and a consumption of oxygen, 

 but no additional formation of nitric acid. On re-aerating, however, a portion of the 

 solution in bottle II., remaining from the experiment, and keeping it in two 

 bottles for further periods, one of four, and another of six months, we find a 

 formation of carbon dioxide and a consumption of oxygen, accompanied by a 

 formation of a decided quantity of nitric acid. 



The carbon dioxide and nitric acid formed during this last fermentation must 

 have been derived solely from the peaty matters present in the solution. They 



