PURIFICATION OF WATER FOR DRINKING PURPOSES 199 



"f V 



Finely Sifted and Sterilised Aluminium Oxide 

 Temperature at which vessels were kept = 9 C 



1 Still slightly turbid after 20 hours. 



2 Still slightly turbid after 30 hours. 



Pulverised and Sterilised Brick 

 Temperature at which vessels were kept = 7 C. 



1 Liquid was clear after 2i hours. 



Liquid was almost clear after 7 hours. 



Pulverised and Finely Sifted Sterilised Vegetable Charcoal 

 Temperature at whfch vessels were kept= 7 C. 



1 Sli-htly turbid after 20 hours. 



Slightly turbid after 30 hom>. 



