156 



BACTERIOLOGY. 



When ready for use the cylinder e is filled with mer- 

 cury up to about the level shown in the figure. It is 

 then allowed to stand, or is suspended, in the bath the 

 temperature of which it is to regulate. The rubber 

 tubing coming from the gas-supply is attached to the 



FIG. 31. 



Mercurial thermo-regulator. 



outer end of the glass tube a, and the tube going to the 

 burner is slipped over the branch tube 6. The gas is 

 turned on and the burner lighted and placed under the 

 bath. The gas now streams through the tube a into the 

 cylinder e and out at b to the burner ; but as the tern- 



