COXDITIOX OF FAT 11 



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

 combination, or whether the\' exist as glyceride of but\Tin, 

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

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

 tion of the diftcrent fats must be as follows : 



BuUrin. Olein, Stearin, 



[ C4H7O2 [ CHsaOo [ C1SH30O2 



CsH.- • C4H7O2 C:,H., ' C1SH33O2 C3H, C]sHo.,02.etc. 



I C4H7O2 1 C,sH3302 I C,sH3.-,02 



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

 the remainder of the fats in butter-fat. 



Richmonrl and other authors belie\X' that fat pirobably exists 

 in milk chemically, as first menticjned and illustrated; because. 

 if the fat were a mixture of ghxerine tributATate with other 

 gh-cerides of fat, but\Tin or gl_\"cerol tributXTate could Ije dis- 

 sohx-d out by the use of alcohol. But this is not the case. I\Iorc- 

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

 to distill it oil under reducerl 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 b}- direct micniscniiical obser\-ati<in 

 whether there is a membrane around each globule or not, Flei.-eh- 

 mann and Lloyd assert that, so far as the\' 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 simpl\- due t(j surface tension, 

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

 tion for themselves than the\- ha^•e for the mcdecules of the serum 

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

 arguments are advanced, 



d) The natural milk-fat may be remo^•ed 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 



