v] CHANGES WHICH MILK UNDERGOES 61 



so that all further consideration of the subject may 

 be postponed till then. 



Preserved Milk. The sterilisation of milk by 

 submitting it to a high temperature, while not always 

 necessarily effective, is accompanied by the objection 

 that it imparts to the milk a flavour peculiarly dis- 

 agreeable to many persons. On the other hand, 

 sterilisation by " intermittent sterilisation " is an 

 extremely inconvenient method, and is utterly un- 

 suited for practical work. Many attempts have 

 been consequently made in the past to convert milk 

 into some form in which it will keep without under- 

 going decomposition. These attempts have all taken 

 the form of preparing milk in a condensed form. At 

 first preserved milk was sought to be prepared by 

 evaporating milk to dry ness. The solids thus left 

 behind, after being mixed with a small quantity of 

 bicarbonate of soda, were then pressed into the form 

 of cakes. This method, however, did not meet with 

 success. In the first place, the cakes were found 

 not to keep well, since the fat soon acquired a rancid 

 flavour. It was also found that such cakes did not 

 dissolve properly in water, the drying process having 

 destroyed the colloidal condition of the caseous 

 matter. It was subsequently discovered that, by 

 simply condensing the milk to about one-half or one- 

 third of its volume, a condensed milk which kept 

 fairly well could be prepared, and that the addition 



