10 BUTTER-MAKING 



carmine, and the cream washed with water until it is free 

 from milk-sugar, a stained layer is present around each globule. 



(2) He has succeeded in isolating this gelatinous substance 

 from cream and butter. Owing to its existence in these two 

 substances, he assumes that it is also present in milk. 



(3) When ether is added to milk, the fat globules dissolve 

 with difficulty, unless some alkali is added to the milk first. 



(4) Bichamp maintains that when ether is added to milk 

 the fat-globules are enlarged due to the ether passing through 

 the supposed membrane by the process of osmosis. He con- 

 siders this fact sufficient to prove that there is a membrane 

 encircling each globule. 



(5) Butter containing 85 to 86% fat is asserted by Rich- 

 mond to have the same consistency as cream containing about 

 72% fat at the same temperature. The sofidity of butter 

 is due to the close proximity of tlie fat-globules. Now, if 

 cream with less fat has the same consistency as butter, the 

 proximity of the fat-globules must be equal to that of the 

 butter; this would indicate that there is a membrane and 

 that this membrane increases the size of the fat-globules. 



(6) The fact that cream separated by centrifugal force is 

 more easily churned than cream of same richness separated 

 by gravity methods, would also be explained if the fat glob- 

 ules in milk had such a membrane surrounding them. 



This membrane, or what is believed to be a membrane, 

 Storch has isolated and analyzed. He finds it to consist of 

 94%, of water and 6% of proteid. 



The reasons deduced by Storch are strong; and the behavior 

 of cream and butter renders it probable that there is such a 

 membrane enveloping each globule of fat. 



Classes of Fats. 



There are two great classes or groups of fats present in the 

 butter, namely: 



(1) Volatile and Soluble, 



(2) Non-volatile and Insoluble. 



