96 REPORT OF THE AGRICULTURAL RESEARCH INSTITUTE 



hydrogen is liberated in addition to these two. In the 

 former case, during the factory period of fermentation,, 

 about twelve hours, nitrogen forms sometimes as much as 

 98 per cent, of the evolved gases, the remainder being carbon 

 dioxide; later these proportions are slowly reversed, but 

 this reversal is of no importance as not affecting factory 

 conditions and requiring 48 hours to 60 hours to complete. 



In the second case the evolved gases after twelve hours 

 are composed of about equal parts, some 33 per cent, each of 

 nitrogen, hydrogen, and carbon dioxide. It is remarkable 

 that no trace of methane has been found in any of the 

 numerous fermentations carried out, and it is also of great 

 interest to note that in some instances in contradistinction 

 to the high nitrogen evolution frequently found, very small 

 quantities of this gas were evolved. 



It is clear therefore that the character of the fermenta- 

 tion must be governed by that of the bacterial complex 

 fortuitously present, and that this may vary essentially and 

 profoundly even in contiguous localities. This variation 

 will have a special interest and importance in connection 

 with the decomposition of organic matter in soil under 

 varying conditions, and must be taken into careful consider- 

 ation in advancing any theories based upon observation of 

 chemical changes due to bacterial action in soils under 

 otherwise apparently similar conditions. 



Numerous species of bacteria have been isolated in the 

 course of this enquiry and their physiological activities 

 with regard to the processes of fermentation investigated. 

 It has been possible to place some of them definitely either 

 in the class of beneficial or deleterious organisms, but much 

 further work will have to be done before their true func- 

 tions in this connection are fully understood. It is of 

 interest to note that one bacterium has been identified with 

 the unfortunate condition which sometimes arises in the 

 " beating " or oxidizing process known as " green vat." 



Biological analysis of soils. Numerous samples of 

 soil from various districts were analysed by the biological 



