196 The Story of the Bacteria 

 Impure Ice 



The use of ice in preserving food and for 

 drinking purposes has become a very impor- 

 tant factor in modern life, and a means of 

 incalculable benefit to all classes of people. 



It was formerly believed that freezing de- 

 stroyed in large measure the impurities of 

 water, and within certain limits this is true. 

 But it has been found, as the result of a long 

 series of careful experiments by numerous in- 

 vestigators, that those important contamina- 

 ting elements in polluted water, the bacteria, 

 may resist for long periods the influences of 

 cold. Good ice is so clear and beautiful that 

 it is difficult to believe that it may harbor 

 among its crystals large numbers of even such 

 tiny bodies as the bacteria, but this is never- 

 theless quite true. 



It has been found that the ordinary do- 

 mestic ice contains large numbers of bacteria. 



It has been further found that that most 

 dreaded form of bacteria, the typhoid bacillus, 

 may remain for long periods living and 

 virulent in solid ice blocks. 



