392 Bacteria in Relation to Country Life 



within twelve hours, or should be immediately cooled 

 down to between 45 and 50. The intelligent use 

 of pasteurizing apparatus, and the intelligent treat- 

 ment of the milk subsequent to pasteurization, can 

 not but prove a decided benefit to all city populations, 

 and, particularly to those whose sources of supply are 

 distant. 



Treatment with chemicals. Substances like borax, 

 boric acid, hydrogen peroxide, salicylic acid, benzoate 

 of soda, sodium sulfite, common salt, saltpeter and 

 formalin have been used for retarding the decompo- 

 sition of foods. It was believed that, unlike the more 

 violent poisons, such as corrosive sublimate and car- 

 bolic acid, these materials could be used in small amounts 

 without marked injury to the health of the people con- 

 suming the food thus treated. The use of common 

 salt and of saltpeter for pickling vegetables, fish, or 

 meat products, is of ancient origin. These substances 

 are not generally regarded as particularly injurious, 

 even when they are consumed in comparatively large 

 quantities. 



State and federal regulations prohibit, however, 

 the use of antiseptics and preservatives in food prod- 

 ucts except under certain specified limitations. The 

 use of preservatives in milk is not allowed at all, it being 

 recognized that, whatever difference of opinion may 

 exist concerning their use in small quantities in other 

 foods, their presence in milk would be a source of grave 

 danger to children. 



Recent investigations indicate that hydrogen peroxide 

 and formaldehyde can be employed in quantities small 



