PURIFICATION OF WATER FOR DRINKING PURPOSES 175 



short time. Freudenreich 1 points out that although 

 opinion in Germany is much divided as to the value of 

 this filter, yet in France there appears to be no hesita- 

 tion in accepting it as a thoroughly 

 reliable purifying agent. Miquel 2 

 in commenting upon the results 

 of some very carefully conducted 

 experiments says : 'Par consequent 

 le filtre en biscuit de Chamber- 

 land est capable de retenir tous 

 les organismes contenus dans les 

 liquides.' 



It is on account of the conflict- 

 ing opinions expressed concerning 

 this filter that Freudenreich 3 has 

 made a special study of its be- 

 haviour as regards micro-organ- 

 isms. He draws attention to the 

 fact that the pressure under which 

 the filter works is not able to force 

 the bacteria through the pores of 



the biscuit-porcelain, and that the FlG 15 . P ASTEUB . C HAMBEB. 

 presence of organisms in the filtrate LAND FlLTER - 



-, , , A, tap on service-pipe ; B, external 



IS due rather tO their eTOWth and metal cylinder ;c,poronspon- 



lain cylinder ; D, glazed porce- 



multiplication within the pores of 1 ^ er delivery ~ tube for mteml 

 the filter, which takes place the 



more rapidly the higher the temperature of the room 

 in which the filter is kept (Kttbler, also Nordtmeyer, 

 Zeitschrift fur Hygiene, vol. x.). To satisfy himself as 

 to this point, Freudenreich made the following series'of 

 examinations : 



1 Ueber die Durchlassigkeit der Chamberland'schen Filter f'iir 

 Bakterien,' Centralblatt fur Bakteriologie, vol. xii. 1892, p. 240. 



2 Analyse Micrographique des Eaux. 



3 Loc. cit. 



Paris, 1891, p. 174. 



