1884 



Journal of Applied Microscopy 



Fermentation Tube for Analysis of Gas Generated by Bacteria. 



The following device has been found convenient for collecting gas in quanti- 

 ties large enough for an exhaustive analysis (Fig. 1). The fermentation-tube A 

 is sterilized in live steam and filled with the medium while the stop-cock is open, 

 the object being to fill the opening of the stop-cock with fluid. The stop-cock 

 is then closed and the medium inoculated. At the end of 24 or 48 hours, when 

 a sufficient quantity of gas has generated, the end c is filled with water and con- 

 nected by means of a rubber tube with an eudiometer. By opening the stop-cock 

 while gently blowing through the tube a the gas is expelled. The fermentation- 

 tube can then be washed with sterile water and again filled with the medium plus 

 the organism, and another quantity of gas obtained. This may be repeated 

 several times until a sufficient amount of gas is secured. A convenient method 



B A 



Fig. 1. — Fermentation Tubes for Collecting Gas for Analysis. 



of analysis by absorption is to use the tube B. This is filled with the absorbing 

 fluid, while the outlet h is held closed by the index finger. When filled to the 

 mark d the open end is closed with a stopper, so as to prevent the fluid from 

 running out through the side-tube. The latter is then connected with c and the 

 gas expelled into B, while passing through the absorbing fluid. The non-absorbed 

 gas may then be collected in similar manner for future analysis. The fermentation 

 tube can also be utilized for making cultures from the growth in the closed arm. 

 By means of a fine capillary pipette, fine enough to pass through the opening in the 

 stop-cock, a sufficient amount of the culture may be obtained for further inocu- 

 lation. 



The tubes are manufactured by Arthur H. Thomas Co., Philadelphia, Pa. 

 Delaware State Board of Health Laboratory. A. ROBIN. 



