LESSON IV 



Examination of Water (continued) II. Qualitative Examination 

 Examination of Water for the Bacillus of Typhoid Fever and the 

 Bacterium Coli Commune. 



II. Qualitative Examination of Water 



A. EXAMINATION OF WATER FOR THE BACILLUS OF 

 TYPHOID FEVER AND THE BACTERIUM COLI COMMUNE. 



Two samples of water are supplied (A) and (B), of which 

 (A) contains typhoid bacilli, and (B) a mixture of typhoid 

 bacilli and the Bacterium coli commune. 



(1) Take 500 to 1000 cc. of each sample and filter through 

 sterile Berkefeld filters into sterilised flasks (vide Fig. 5), 

 which are connected with an air-pump. 



The filters should be previously sterilised in the auto- 

 clave, the flasks in the hot-air steriliser. 



(2) Pour 10 to 20 cc. of the filtered water, which is sterile, 

 into a small sterilised beaker, protected with a sterile 

 cotton- wool plug. 



(3) Now unscrew the " candle " of the filter. 



(4) With a soft sterilised tooth-brush gently scrape the 



