Composition of Cheese. 



even a fter long standing 1 , skimmed-milk is always more or 

 less opaque. We must find, therefore, in the cheese made 

 from skimmed-milk a certain amount of butter, though much 

 less than in whole-milk cheeses. On the removal of the cream 

 the milk becomes bluer and more transparent ; and hence the 

 transparent and peculiarly blue appearance of some of the London 

 milk is indicative of its poorness. On allowing milk to become 

 acid, which it does readily in warm weather, one of its con- 

 stituents, which, from its sweet taste, is called sugar- of-milk, is 

 converted, at least in part, into lactic acid. This change is 

 effected by simple transposition of the elementary particles of 

 milk-sugar, without anything being added or detracted from 

 them. This lactic acid again separates the next constituent, 

 the casein or curd of milk, which may also be separated by 

 rennet. On the removal of the casein, either artificially by 

 rennet or naturally by the lactic acid, we obtain whey ; and, 

 provided this whey is perfectly clear and free from all butter 

 and curd (which is not generally the case) in our dairies, we 

 may, by evaporating the clear liquid, obtain milk-sugar and a 

 certain quantity of matter which is incombustible, and consti- 

 tutes the ash of milk. These then are the principal constituents 

 of milk curd or casein, butter, milk-sugar, and mineral matters 

 or ash. Now, in the preparation of cheese we separate the curd 

 or casein, and, if we want to make good cheese, also the butter 

 and a small quantity of mineral matter contained in the milk. 

 In the whey remains the milk-sugar and most of the mineral 

 matter. A glance at the subjoined diagram, which gives the 

 composition of different kinds of milk lately analysed by me, will 

 show the enormous difference that exists in the relative amounts 

 of the various constituents of milk. 



Composition of New Milk. 



