i8 LABORATORY GUIDE IN BACTERIOLOGY 



filtered rapidly by the use of suitable apparatus, as illus- 

 trated in Fig. 10. At the connection with the vacuum 

 pump a valve should be inserted or a flask with a rub- 



FIG. 10 

 Filtering Media by Means of Vacuum Pump 



a. Liquid medium e. Reflex flask 



b. Absorbent cotton /. Rubber stopper with two holes 



c. Rubber stopper g. Connection with aspirator 



d. Filtered medium 



ber cork with two holes may take its place to prevent 

 the water from entering the flask. 



Whichever method is employed, the filter must always 

 first be soaked in hot water, or, better, kept in steam 

 until used. 



