PREPARATION OF CULTURE MEDIA 



21 



fastened by means of thumbscrews (Fig. 12, d-d). The 

 heat is produced by two circular sets of Bunsen burners 

 in a hollow cylinder at the bottom (Fig. 12, e). 



Other forms based on the same principles are also 

 in use. 



Before using the autoclav the inside should be exam- 



Pic. 12 

 Autoclav 



a. Steam-valve 



b. Safety-valve 



c. Gauge 



d-d. Thumbscrews 



e. Bunsen burner and 

 opening 



ined. It must be clean, and there must be enough clean 

 water in it to reach nearly to the bottom of the basket. 

 Water containing large amounts of impurities is liable to 

 foam when boiling, and thus wet the plugs and ruin the 



