BUTTER. 225 



ful and complete washing the greater part may be 

 removed. Salt is generally added, as its presence 

 greatly checks the tendency of the caseine to change, 

 and consequently helps to keep the butter sweet. 



576. In making butter there are two distinct meth- 

 ods employed. The one consists in churning the 

 entire milk, the other in churning the cream alone ; 

 the latter is said to give the richest and finest butter, 

 though^' the former is considered to give a larger 

 yield. In either case a certain amount of incipient 

 fermentation appears to be essential to the process of 

 churning, and a moderate degree of warmth, as well 

 as the contact of atmospheric air, are necessary. 



577. The milk or cream intended to make into 

 butter, is not used perfectly fresh, but is always 

 allowed to stand some little time, in order that it may 

 pass into this state of incipient fermentation, and a 

 small quantity of lactic acid may be formed. The 

 same state may be immediately brought on by the 

 addition of a little sour cream, which acts on the 

 rest as a ferment. There is some danger in doing 

 this, however, that the whole may pass into the pu- 

 trid fermentation (380). 



578. In consequence of the extreme facility with 

 which caseine undergoes decomposition, and the rapi- 

 dity with which it passes into the state of putrid fer- 

 mentation, the utmost care and attention must always 

 be paid to insure complete cleanliness in the dairy. 

 The least taint of impurity in the vessels employed, 



