l88 BACTERIA, YEASTS, AND MOLDS 



preserve milk in a tenement house without, the use of ice. 

 The grocer keeps the milk on ice, and the customer buys 

 it in small quantities to be consumed at once. This would 

 be a proper arrangement if it were not for the fact that 

 poorer kinds of milk find their way into these groceries, 

 and are likely to be kept until old, so that as a rule the 

 milk thus purchased is the poorest grade that reaches the 

 market. It is usually sold at a small price, but is of such 

 poor quality that the poorer classes themselves would be 

 much wiser to purchase a better grade. 



By the removal of part of its water the keeping property 

 of milk may be increased. Condensed milk is such a prod- 

 uct, which, after condensation, is commonly preserved by the 

 addition of about 40^ sugar or by sterilizing. It is a useful 

 product, but cannot exactly replace fresh milk. A type 

 sometimes called concentrated milk has three quarters of 

 its water removed by evaporation at 140°. This destroys 

 disease germs and brings the milk into a condition in 

 which it will keep for many days. When, subsequently, 

 the water is restored, the material is indistinguishable from 

 fresh milk and will be easily substituted for it. 



But our care should not cease with the scrutiny of its 

 source. Even though originally of the highest character, 

 milk will not keep in our homes unless properly treated. 

 The keeping . of milk depends upon temperature and 

 cleanliness in the pantry. 



2. Milk Vessels. Special care should be given to the 

 vessels in which milk is received and kept. A large part 

 of the trouble which the housewife experiences in keeping 

 milk is due, not to the milkman, nor to the character of 

 the milk which she purchases, but to the condition of the 



