266 BACTERIOLOGICAL EXAMINATION OF WATER. 



In 1892 Freudenreich re-investigated the possibility of the 

 passage of bacteria through the Pasteur-Chamberland filter. 

 A bougie was sterilised, and the case having been screwed on to 

 a tap, Seine water was passed through the bougie under a 

 pressure of one-third of an atmosphere ; 830 c.c. of the filtrate 

 were collected in a flask containing 500 c.c. of broth ; the flask 

 was then incubated at 30-35 C. The filter was maintained in 

 use for three days, water being allowed to pass through drop by 

 drop; 760 c.c were then collected as before. After another 

 three days 610 c.c. were again collected. All the flasks were 

 found to be free from bacteria after incubation for twelve days 

 at 35-37 C. A similar experiment was made with Ourcq water, 

 and these flasks also remained sterile. The results of the ex- 

 periments appeared to show that a sterile filtrate was delivered 

 from the filter for a period of six days. As the results were 

 quite at variance with the experiments of Kubler, Freudenreich 

 then devised an experiment to test the possibility of micro- 

 organisms going through the walls of the filtering candle. A 

 porcelain candle of known structure was taken, and a pipette, 

 with a globular enlargement above was passed through the 

 opening to the bottom of the bougie ; the mouth of the pipette 

 was plugged with cotton-wool and the whole sterilised in the 

 autoclave. After sterilisation the junction of the pipette to 

 the bougie was closed with melted paraffin ; the bougie was 

 then placed in a glass vessel filled with water and kept at a 

 known temperature. At various intervals some of the water 

 which had filtered through the bougie was aspirated into the 

 expansion on the pipette and then inoculated in broth. 



The same apparatus was next used to see if typhoid bacilli 

 were able to grow through the walls of the filtering candle. Broth 

 placed in the glass vessel was inoculated with a B. typhosus cul- 

 ture and the apparatus was kept at the room temperature. Next 

 day there was a marked growth in the broth. At various intervals, 

 up to the end of fourteen days, portions of the filtered broth 

 were aspirated through the pipette but were found quite clear. 

 On the fourteenth day 3 c.c. were drawn through the pipette- 

 and placed in 200 c.c. of sterile broth ; this, however, remained 

 quit? sterile. In three other experiments the filter was kept at 

 35 C., and portions of the filtrate examined after twelve, fifteen. 



