COMPOSITION OF BUTTER. 3 



decomposition of the fatty and the albuminous portion, this 

 change being retarded by the addition of salt ; hence butters 

 are commercially distinguished as fresh and salt butters. 



Its constituents are in all cases the same as those which 

 enter into the composition of milk and cream, namely, 

 fat, water, casein, sugar of milk, and mineral matters, con- 

 sisting for the most part of alkaline phosphates. To these is 

 to be added the salt used in its preparation and for its preser- 

 vation. The proportion of sugar of milk, which in some cases 

 is for the most part changed into lactic acid, is always very 

 small, it never amounting to more than a few hundredths of a 

 percentage. Hence it may in all cases be safely disregarded. 



I. The Fat of Butter. Butter-fat is a highly complex 

 substance, including a greater variety of glycerides than any 

 other fat known. It has long been regarded as a mechanical 

 mixture of different glycerides, but the latest researches, 

 which will be found in another chapter, go far to prove it to 

 be not a mixture of tri-glycerides, but a mixed ether, a tri- 

 glyceride containing different acid radicles. 



The acids, which are said to occur in butter-fat, in combi- 

 nation with glycerin, are palmitic, stearic, and oleic, butyric, 

 caproic, caprylic, and capric. Besides these (the occurrence of 

 at least one of which is doubtful), there have been alleged to 

 be present margaric and butyroleic acids, which, however, are 

 now no longer recognised as distinct compounds naturally 

 occurring. 



As a great part of the methods of butter analysis detailed 

 in this book cannot be properly understood without a know- 

 ledge of the properties of the acids enumerated and of their 

 tri-glycerides, we shortly append their physical and chemical 

 characteristics. 



Palmitin, CgjHggOg or C 3 H 5 (C 16 H 31 2 ) 3 is a white solid 

 substance, sparingly soluble in cold, far more so in hot 



