82 CULTIVATION OF ANAEROBIC BACTERIA. 
50, and this is connected with a hydrogen apparatus by a rubber 
tube, The hydrogen is allowed to bubble through the culture 
liquid in a full stream for ten to fifteen minutes, in order that all of 
the oxygen in the flask may be removed by displacement. Then, 
while the gas is still flowing, the flask is sealed at a with a blow- 
pipe flame, the hydrogen tube being left in position and melted fast 
to the flask. Some little skill is required in the successful perform- 
ance of the last step in this procedure, and it will be easier for those 
A 
Fie. 49, Fia. 50. Fic. 51. 
who are not skilful in the use of the blowpipe to use Salomongon’s 
tube, shown in Fig. 51. In this, hydrogen is admitted through the 
arm b, and escapes through the cotton plug a. The vertical tube is 
sealed at c while the gas is flowing, and then the horizontal tube at b. 
Frdnkel’s Method.—Instead of these tubes specially made for 
the purpose, an ordinary test tube may be used, as recommended by 
Frankel. This is closed by a soft rubber cork through which two 
glass tubes pass—one, reaching nearly to the bottom of the test tube, 
