CONDITION OF FAT 11 



Condition of Fat. Whether the fats in milk exist in chemical 

 combination, or whether they exist as glyceride of butyrin, 

 stearin, olein, etc., in the form of a mechanical mixture, is & 

 question in dispute. If they exist in the latter form, the composi- 

 tion of the different fats must be as follows : 



Butyrin. Olein. Stearin. 



' C 4 H 7 2 



Ci8HssC)2 



Ci 8 H 3 5O 2 ,etc. 



C 4 H 7 2 



and the total fat made up of a mechanical mixture of these and 

 the remainder of the fats in butter-fat. 



Richmond and other authors believe that fat probably exists 

 in milk chemically, as first mentioned and illustrated; because, 

 if the fat were a mixture of glycerine tributyrate with other 

 glycerides of fat, butyrin or glycerol tributyrate could be dis- 

 solved out by the use of alcohol. But this is not the case. More- 

 over, if butyrin existed separately in milk, it would be possible 

 to distill it off under reduced pressure. This cannot be done. 



Theory in Regard to Films Enveloping Fat-globules. The 

 extreme minuteness of the fat-globules in milk renders it almost 

 impossible to determine by direct microscopical observation 

 whether there is a membrane around each globule or not. Fleisch- 

 mann and Lloyd assert that, so far as they were able to detect, 

 there is no real membrane surrounding each globule. 



The theory generally accepted in the past was that the film 

 surrounding the fat-globules was simply due to surface tension, 

 or to the fact that the molecules of the fat have a greater attrac- 

 tion for themselves than they nave for the molecules of the serum 

 in which they are held in suspension. In support of this two 

 arguments are advanced. 



(1) The natural milk-fat may be removed from milk and 

 artificial fat substituted in its place. The resultant milk has 

 characteristics similar to milk containing normal fat, that is, the 

 emulsion which milk forms with the artificial fat is apparently 

 like that formed with the natural fat. 



(2) If there were a special albuminous membrane around 



