PURIFICATION OF WATER FOR DRINKING PURPOSES 171 



water. These materials, coke and vegetable charcoal, 

 are also especially well fitted for use in breweries and 

 distilleries, where it is so necessary to have a water 

 which, though perfectly free from organic life, is at the 

 same time free from antiseptic substances, such as iron, 

 which militate against fermentation. 



Here also on the small scale we have the import- 

 ance of the rate of filtration emphasised, the greater 

 rate which prevailed in the second series of experi- 

 ments causing the efficiency to deteriorate more 

 rapidly. 



In the case of animal charcoal it will be seen that 

 after one month's action there was a large increase in 

 the numbers of microbes present in the filtrate, thus 

 clearly demonstrating the necessity of its frequent 

 renewal when used for filtration purposes. 



We have appended the following table giving the 

 chemical analysis of the water before and after passing 



Chemical Analysis of Water before and after Filtration, through 

 Coke and Charcoal respectively (Percy Frankland) 



Eesults of Analysis expressed in parts per 100,000 



