CHAPTER V. 

 preservation bg Cooling. 



From the experiments previously noted, it will have 

 become clear what influence temperature has on the 

 propagation of bacteria, and this influence is so much 

 stronger inasmuch as the temperature can be lowered, 

 and, naturally, it was not long before attempts were 

 made to ascertain the keeping qualities of frozen milk. 

 In some cases this expedient is resorted to where milk 

 is to be preserved for long journeys. A part of the 

 milk supply of Paris, France, is brought to town in 

 this form, frozen by machinery in vessels with elastic 

 sides and then thawed out before consumption. It is 

 reported that this milk does not differ either in ap- 

 pearance or in taste from fresh milk, and that it can 

 be worked into the products of milk with good results. 

 Also on board of some of the trans-Atlantic steam- 

 ships frozen milk has been shipped for use for years. 

 This milk is first treated in a refrigerator, and then 

 frozen. The freezing of milk, however, has one seri- 

 ous disadvantage, which consists in the disintegration 

 of milk during the freezing process, which, notwith- 

 standing the previous refrigerating, consumes several 

 hours of time, and, consequently, the cream separates. 



This frozen block consists of skim milk, on which 



