vn] BACTERIA IN BUTTER-MAKING 131 



in America a larger limit seems to be -supported. A 

 large number of analyses of American butter showed 

 an average of about 19 per cent of water. The ques- 

 tion is of considerable importance, since the amount 

 of water undoubtedly affects the quality. The per- 

 centage of fat may be said to vary from 82 to 85 per 

 cent, the other constituents the casein, albumin, and 

 ash forming, on an average, not much more than 

 1 per cent. For preserving purposes salt is often 

 added to butter. 



The following may be regarded as the average 

 composition of fresh and salt butter : 



Fresh Butter. Salt Butter. 



Water . . 14-00 12-50 



Fat . . . 83-50 84-50 



Protein . -80 -50 



Milk, Sugar, etc. . 1'50 -60 



Ash ... -20 -10 



Salt 1-80 



100-00 100-00 



The following diagram illustrates the appearance 

 of butter under the microscope (see Fig. 20, p. 132). 



Margarine. Before concluding this Chapter, it 

 may not be out of place to say a word or two on that 

 largely used butter substitute, oleomargarine, or, as 

 it is more commonly known, margarine. Having 

 regard to the present enormous dimensions of the 

 trade in margarine, it is striking to reflect that its 



