HOUSEHOLD BACTERIOLOGY 



Purifying 

 Water 

 Filters 



Porcelain 

 Filter! 



supply which receives any house drainage or that from 

 manured fields is in danger of contamination at any 

 time. 



Impure water may be purified from all germs by 

 boiling for half an hour. Such water, having lost 

 the air which was dissolved in it, tastes insipid. The 

 air may be restored by pouring the water a few times 

 from one clean vessel into another, and this should be 

 done in a clean place, that is, where there is little fly- 

 ing dust. 



Most filters simply strain out visible suspended mat- 

 ter or invisible but comparatively large animal or veg- 

 etable forms. A flannel bag will do this, and it can 

 and should be cleaned daily. It clears currant jelly, 

 why not water? When charcoal forms a part or the 

 whole of the straining medium, more organic matter 

 is removed and therefore more color is taken out, but 

 the charcoal soon loses its purifying power and must 

 be cleaned or renewed. None of the ordinary faucet 

 filters will remove the minute disease germs and there- 

 by make a polluted water safe for drinking. Germ 

 removal requires a very fine medium, which means 

 slow straining. Certain filters, made of very fine un- 

 glazed clay or similar substance, take out the germs 

 themselves, but cannot remove the products of their 

 life processes, which are soluble. In some cases these 

 are as dangerous as the germ plant itself. If a filter 

 does strain out the bacteria, then it is evident that 

 the straining medium will become foul with them and 



