138 DISINFECTIONSTERILIZA TION— DISINFECTANTS 



and disinfecting streets, but it is very doubtful if the added 

 expense is justified by any increased benefiit. A number of 

 electric devices have been put forth for various sterilizing 

 and disinfecting purposes and doubtless will continue to be, 

 but every one should be carefully tested before money is 

 invested in it.^ 



Fig. 98. — Suction filtration. A, Berkefeld filter in glass cylinder con- 

 taining the liquid to be filtered; B, sterile flask to receive the filtrate as it is 

 drawn tlirough; C, water pump; D, manometer, convenient for detecting 

 leaks as well as showing pressure; E, bottle for reflux water. 



7. Filtration.— Filtration is a process for rendering fluids 

 sterile by passing them through some material which will 



1 The author has tested an "electric milk purifier" (Fig. 96) which was 

 as efficient as a first-class pasteurizer and left the milk in excellent condi- 

 tion both chemically and as far as "cream line" was concerned. The cost 

 of operation as compared with steam will depend on the price of electricity. 



