FERMENTATION OF CELLULOSE 165 



case of the hydrogen bacillus the following products were 

 obtained from the original weight of 3' 3471 grams of paper : — 



Fatty acid . . . . 2-2402 



COg -9722 



H 0138 



3'2262 grams 



The marsh-gas fermentation yielded the following products 

 from 2'0065 grams of paper : — 



2-0073 



The fatty acids consisted mainly of acetic acid, together 

 with smaller quantities of butyric acid. 



3. The fermentation of cellulose above described takes 

 place in absence of air. It is obvious, however, that much of 

 the natural destruction of cellulose, e.g., the mass of dead 

 leaves which fall each autumn, must take place in presence 

 of air. 



Researches by Van Iterson have indicated various methods 

 by which this breaking up can take place. He found that in 

 presence of nitrates certain organisms are capable of oxidising 

 cellulose, utilising the oxygen of the nitrate which is simul- 

 taneously reduced. The following experiment will illustrate 

 this action : — 



100 c.c. of tap water are placed in a 200 c.c. flask together 

 with 2 grams of Swedish filter paper, 0-25 gram potassium 

 nitrate, 0-05 gram potassium hydrogen phosphate (K2HPO4), 

 a few c.c. of sewage and a Kttle leaf mould. The flask is then 

 filled to the neck, plugged with cotton wool and placed in an 



