162 WORCESTER SOCIETY. 



butter, and consequently the reputation of their dairy, be in- 

 jured." 



" Batter contains two kinds of fat. If melted in water at 

 about one hundred and eighty degrees Fahrenheit, a nearly col- 

 orless oil is obtained, which becomes solid on cooling. If the 

 solid mass be subjected to pressure in a strong press at about 

 sixty degrees Fahrenheit, a pure liquid oil runs out, and there 

 remains a solid white fat. The liquid fat is called oleine, and 

 the solid fat, 7nargarine. These two bo,dies are present in 

 many other animal and vegetable oils and fats. They are both 

 nearly tasteless, and when quite pure, will keep without change 

 for a long time. In presence of certain impurities, however, 

 they do change." 



" If great care is not taken in washing and working, when 

 making butter, some butter-milk is left enclosed in it ; the but- 

 termilk, of course, contains casein, the nitrogenous body which 

 we have already described ; there is also some of the milk 

 sugar before mentioned. The casein, like all other bodies con- 

 taining much nitrogen, is very liable to decomposition. This 

 soon ensues, therefore, whenever it is contained in butter ; and 

 certain chemical transformations are by this means soon com- 

 menced, whereby the margarine and oleine are in part changed 

 to other and very disagreeable substances, those which give the 

 rancid taste and smell, to bad butter. The milk sugar is instru- 

 mental in bringing about these changes. It is decomposed into 

 an acid by the action of the casein and has a decided effect 

 upon the fatty substances of butter, causing them to become 

 rancid. This action and consequent change come on more 

 or less rapidly, as the temperature is warmer or colder." 



" No matter how well the butter is made in other respects, if 

 buttermilk is left in it, there is always, from the causes above 

 mentioned, a liability to become rancid and offensive. When 

 packed in firkins, it will be rancid next to their sides and tops ; 

 will be injured to a greater or less depth, as the air may have 

 obtained access. Salting will partially overcome the tendency 

 to spoil, but not entirely, unless the butter is made so salt as to 

 be hardly eatable. Another reason for much poor butter, which 

 is unfortunately too common, is to be found in the impure 



