2QO METHODS OF IDENTIFICATION AND STUDY 



(glucose, lactose, etc.). The medium should be prepared from 

 inosite-free bouillon (vide page 183). 

 Reagent Required: 



- caustic soda. 



2 



METHOD. 



1. Inoculate the surface of the medium in the bulb 

 of a fermentation tube and incubate. 



2. Mark the level of the fluid in the closed branch of 

 the fermentation tube, at intervals of twenty-four hours, 

 and when the evolution of gas has ceased, measure the 

 length of the column of gas with the millimetre scale. 



Express this column of gas as a percentage of the 

 entire length of the closed branch. 



3. To analyse the gas and to determine roughly the 

 relative proportions of C0 2 and H 2 , proceed as follows : 



Fill the bulb of the fermentation tube with caustic 

 soda solution. 



Close the mouth of the bulb with a rubber stopper. 



Alternately invert and revert the tube six or eight 

 times, to bring the soda solution into intimate contact 

 with the gas. 



Return the residual gas to the end of the closed 

 branch, and measure. 



The loss in volume of gas = carbon dioxide. 



The residual gas = hydrogen. 



Transfer gas to the bulb of the tube, and explode it 

 by applying a lighted taper. 



(B) Sulphuretted Hydrogen. 



Media Required: 



Iron peptone solution (vide page 185). 

 Lead peptone solution. 



1. Inoculate tubes of media, and incubate together 

 with control tubes. 



2. Examine from day to day, at intervals of twenty- 

 four hours. 



The liberation of the H 2 S will cause the yellowish- 



