416 GENERAL SCIENCE 



danger appears, however, in the fact that these preserv- 

 atives prevent food from digesting properly and, being 

 poisonous, in time work serious injury to the body. Milk 

 that has not been pasteurized or properly cooled will sour 

 in a day's time in hot weather. If it does not sour it has 

 probably been treated with formaldehyde, which is the 

 chemical commonly used for this purpose. 



Borax and boric acid will make tainted meats appear 

 fresh. Such " doctored " meats are often made into 

 sausage. Benzoate of soda is used in many canned and 

 bottled foods, such as relishes, pickles, and catsups. 



Danger from Water. Nothing is more important to 

 the health of the individual and the community than an 



FIG. 367. Interior of a Ten-foot Intake Water Tunnel. 



abundant supply of pure water. To obtain such a supply 

 and to see that it continues pure should be the serious 

 concern of city and village health boards. If water 

 from rivers or lakes must be used, all possible precaution 

 should be taken to establish efficient filtration plants, 



