CHANGES PRODUCED BY A SAPROPHYTIC ANAEROBE 383 



A series of cultures was prepared in exactly the same way and 

 an analysis made at intervals as indicated in table 4. 



METHODS OF ANALYSIS 



Gas analysis. {Total volume.) The amount of gas could be 

 calculated from the manometer readings and reduced to normal 

 temperature and pressure by using the following formula : 



273 F(P-r) 

 ~ 760 (273 + t) 



in which V = volume, P = barometric pressure in mm. Hg., 

 T = vapor tension of watcr,= 760 = normal pressure, 273 = abso- 

 lute temperature. 



Determinations of the total volume of gas were recorded upon 

 the bottle which remained in the incubator for the longest time. 

 Manometer readings were taken on all the cultures at each 

 interval but not all of these are included in the tables, since they 

 would give no additional information as to the course of the 

 fermentation. 



Method for collection and analysis of gas. To obtain samples of 

 gas, uncontaminated with air, the mercury pump was attached to 

 the slender sealed tip (D) shown in figure 1. A tight fitting 

 rubber stopper was first placed over the sealed tip and the rubber 

 connection forced carefully over the tip until the metal tube came 

 well down over the tip. This was wired firmly in place. Next 

 the large rubber tube, which served as a receptacle for mercury, 

 was drawn down and fitted over the stopper and wired in place. 

 This large tube was filled with mercury to cover the connections 

 completely. 



The mercury pump was filled with mercury as completely as 

 possible and the tube leading from the mercury pump to the con- 

 nection with the culture container was exhausted with the Geryk 

 pump. When the entire apparatus was exhausted, the connec- 



' The vapor tension of water was used in all cases. This probably varied to 

 some extent as the fermentation proceeded and new volatile products were 

 formed. From the fact, however, that these were of unknown value, it was pos- 

 sible to use only the vapor tension of water in our calculations. 



