739 



living at similar temperatures. Analysis of tlie gaseous products 

 obtained in tliese^3xperinients showed no combustible gas(CH4and H). 



(2) Anaerobic fermentation. — In this series of experiments the method 

 of procedure Avas the same as in those described above, except that a 

 current of nitrogen was substituted for air. Tlie gaseous i^oducts were 

 analyzed eudiometrically. Horse manure containing 00 per cent of 

 moisture was used. Temperatures of 52"^ and 60^ C. were maintained, 

 and the experiment lasted 17 days. At 52^ marsh gas was evolved by 

 the inoculated lot, but this evolution ceased at 00°. At 52° the pro- 

 duction of carbonic acid and consequently the decomposition of the 

 organic matter were much greater in the presence of microbes than in 

 their absence, w^hile in their absence decomposition was much greater 

 at 06° than at 52°. In no case did the evolution of carbonic acid equal 

 that in the aerobic fermentation. 



Other experiments were made to determine wliether gaseous nitro- 

 gen is set free when manure ferments without access of air. One hun- 

 dred grams of finely divided manure was put into a 200 c. c. flask, which 

 was immersed in a water bath at 45° C. The flask was connected with 

 an apparatus for measuring the gas evolved. In 2 months there was 

 obtained 850 c. c. of gas containing carbonic acid 713.6 c. c, hydrogen 

 38.8 c. c, and marsh gas 97,6 c. c. Xo nitrogen was present. In a 

 similar experiment at 76.5^ C. the evolution of gas was verj^ lively. The 

 manure did not change in color or odor, but simply became more friable. 

 Ko nitrogen was found in this case. Hydrogen was generated in con- 

 siderable quantity at the beginning of the experiment, but afterward^ 

 this ceased, and only carbonic acid and marsh gas were produced. 

 In 2 months the following results were obtained : 



Analysis of the maniu-e before and after fermentation gave the fol- 

 io win c' results : 



The amount of carbon lost (4.75 grams) agrees with that found in the 

 gasometer (4.72 grams) 5 this is equal to 37.5 jjcr cent of the carbon in 

 the original materiah 



