CHAPTER XXIV 



CHEMICALS AS DISINFECTANTS AND PRESERVATIVES 



231. The prevention of disease epidemics is one of the most 

 striking achievements of modern science. Food, clothing, 

 furniture, and' other objects contaminated in any way by 

 disease germs may be disinfected by chemicals or by heat, 

 and widespread infection from persons suffering with a con- 

 tagious disease may be prevented. 



When disease germs are within the body, the problem is 

 far from simple, because chemicals which would effectively 

 destroy the germs would be fatal to life itself. But when 



germs are outside the 

 body, as in water or 

 milk, or on clothing, 

 dishes, or furniture, 

 they can be easily 

 killed. One of the 

 best methods of de- 

 stroying germs is to 

 subject them to in- 

 tense heat. Contam- 



FlG. 160. Pasteurizing apparatus, an arrangement mated Water IS made 

 by which milk is conveniently heated to destroy safe by boiling f or a 

 disease germs. 



few minutes, because 



the strong heat destroys the disease-producing germs. 

 Scalded or Pasteurized milk saves the lives of scores of 

 babies, because the germs of summer complaint which lurk 



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