DANGERS FROM INFECTED FOOD AND WATER 447 



A SIMPLE PASTEUR- 

 IZING OUTFIT 



killed but the milk itself is not made less digestible nor is 

 its taste affected. This is called pasteurization. The 

 milk should be cooled quickly after it is heated, covered with 

 absorbent cotton, and kept in a refrigerator so that fresh 

 germs cannot infect it. Pasteurized milk 

 is the only safe milk to use unless it is 

 absolutely known that great care has been 

 taken to keep the milk at all times clean 

 and cold enough to be safe from infec- 

 tion. Certain cities require that all milk 

 sold shall either come from healthy cows in 

 dairies of " certified " cleanliness or else 

 shall be pasteurized. Refrigerators and 

 places where milk and food are kept must 

 be washed and thoroughly scalded with hot water frequently 

 if they are to be kept free from bacterial infection. 



Water is also a dangerous carrier of bacteria. Water 

 from deep artesian wells is usually safe, but streams that 

 flow over the surface of the ground continually have washed 

 into them materials which contain germs. Unless great 

 care is taken to keep surface water out of springs or 

 wells and to keep the drainage from stables and out- 

 buildings from seeping into them, they become dangerous 

 as sources of water supply. Impure water is an ever active 

 source of disease and one that cannot be too carefully 

 watched. 



Many of our large cities have in recent years expended 

 vast sums of money upon their water supplies in order that 

 citizens may be protected as far as possible from disease. 

 The drainage canal which Chicago built at great expense to 

 divert its sewage from Lake Michigan greatly lowered the 

 death rate from typhoid fever in that city. Further de- 



