Preservation of Milk. 135 



ilar to cream, and previous to the passage of the pure 

 food law, it was sold as evaporated cream. 



Condensed milk is not wholly free from bacteria, but 

 is sufficiently thick, by reason of its treatment so that 

 the contained bacteria cannot grow. They remain dor- 

 mant in the milk, but as soon as it is diluted to a nor- 

 mal consistency, growth takes place, and the milk rap- 

 idly spoils. Condensed milk is prepared by adding cane 

 sugar to fresh sweet milk, then evaporating the mix- 

 ture to one-third the original volume, forming a semi- 

 solid product. Syrups owe their keeping qualities to 

 the same factor, as condensed milk, i. e., the high consis- 

 tency. 



Milk is also preserved by wholly evaporating the wa- 

 ter, thus leaving a dry powder, which on being mixed 

 with water again will have much the same properties as 

 the original milk. Various methods have been devised 

 for the preparation of these milk powders, all of which 

 have been patented by the inventors. If the powder is 

 to be kept for long periods, skim milk must be used, 

 since the fat slowly undergoes changes which cause it to 

 have a rancid odor. These dry preparations are largely 

 used by bakers in place of fresh milk. 



