ANAEROBIC GROWTH IN HYDROGEN 



117 



be placed in a wide -necked flask or bottle, arranged as 

 shown in Fig. 12. 



(2) Connect the flask with a hydrogen apparatus, and 

 allow hydrogen to pass through it for one hour. 



The hydrogen should be sent through three wash 

 bottles, containing respectively lead nitrate (1 : 10), 

 nitrate of silver (1:10), and pyrogallic acid (added 

 to 1 per cent caustic potash) solutions, in order to 



FIG. 12. 

 I. II. III. Wash bottles ; s, sand ; p, pyrogallic acid and caustic potash. 



remove impurities, such as arseniuretted or sul- 

 phuretted hydrogen (Fig. 12, I. II III.) 



(3) When the air has been replaced by the hydrogen 

 which is best tested by applying a light to the tube a 

 fuse off at a first, and then also at 6, and place the flask 

 in the cool incubator. 



Examine the tubes from day to day, and work them 

 up as already described, i.e. make subcultures in 

 grape-sugar gelatine (stab cultures). 



These must be placed in a wide-necked bottle, through 

 which hydrogen is again passed as before. 



