266 



THE CHEMICAL CONTROL OP THE DAIRY. 



In cream No. 1 the proteins were also calculated, and found 

 to be 2"60 per cent., while the figure calculated on the assumption 

 that they are 37 '8 per cent, of the solids not fat, as in milk, is 

 2 "58 per cent. 



The statement that cream contains a higher proportion of 

 solids not fat to water than milk, though to some extent due 

 to the evaporation of water which takes place, is probably also 

 due to the methods of analysis employed. Thus it is known 

 that when butter fat is heated in contact with air for some hours 

 an increase of weight is noticed. As cream contains from 25 to 

 50 per cent, of fat, an apparent increment in the total solids 

 of from 0"1 to 0'3 per cent, may be noticed. If the fat be esti- 

 mated by a method which avoids a long heating, and the solids 

 not fat deduced by difference, the increment will swell the amount 

 of solids not fat. Many analyses of the fat in cream have been 

 made by methods which do not completely extract the fat ; 

 the solids not fat are thus still further increased. 



The following analyses show the composition of creams : — 



Water, 

 Fat, . 

 Sugar, . 

 Protein, 



Ash, 



99-70 



100-00 



The following table will show the proportion of milk-sugar, 

 protein, and ash to 100 parts of water contained in cream com- 

 pared with those contained in milk and separated milk (see 

 Mean Comfosition on pp. 150 and 260) : — 



Milk-sugar, 



Protein, 



Ash, 



Cream. 



Per cent. 

 5-55 

 4-05 

 0-88 



Milk. 



Per cent. 

 5-45 

 3-90 

 0-86 



Separated Millr. 



Per cent. 

 5-39 

 4-02 

 0-86 



It is impossible to give an average composition of cre.am, as 

 the variation of the fat is enormous ; the author has obtained 

 cream containing 9 per cent, of fat as a minimum, and 68 per 

 cent., and even slightly more, as a maximum. As milk has 

 been known to contain as much as 12 per cent, of fat (from 

 Jersey cows), it follows that no sharp distinction between milk 

 and cream can be drawn. Attempts have been made to fix a 



