EMULSIONS 



135 



The effects of supersonic waves extend into the Kving world; 

 bacteria and other one-celled organisms are killed by them. 

 This fact has led to a consideration of the method as a means for 

 the sterilization of milk. Bacteria in milk would presumably be 

 killed without the milk acquiring the taste that heating gives to 

 it. Still another change is produced in the milk which is also of 

 advantage: the butterfat is more highly emulsified. The drop- 

 lets, now being smaller, are more readily digested. The process 

 is in the experimental stage as yet but has 

 commercial possibilities. 



Natural Emulsions. — It is quite obvious c^^.^''^/^^^^'-2 

 that wherever oil, fatty, or other liquid sub- ^^^ r i^^--3 

 stances insoluble in water occur m nature, -^^ J^^--4 

 there is the likelihood of their being finely 

 dispersed in their aqueous medium. Such 

 natural emulsions are found in both the 

 nonliving world (as in petroleum) and the 

 living world. Among the latter is latex, 



^ , , ,.,.., . . Fig. 89.— The latex 



the rubber-producmg liquid occurring m a (rubber) globule with 

 large variety of plants (Ficus elastica, Hevea (i) the inner kernel of 



, ., . .-r-, 1 1- cii-j j-N r\ low weight hydrocar- 



hrazthensis, Euphorbia, Sohdago, etc.). Un ^ons; (2) intermediate 



coagulating, latex forms a tough elastic mass layer of increasing poly- 

 Which is crude rubber. The latex emulsion hydrocarbon membrane 



consists of dispersed globules of a hydrocar- of maximum poiymeri- 



., 1 .1. 1 1 j_ ■ J • zation; (4) adsorbed 



bon oil, stabilized by protein and resinous ^^^^^ ^f j-ggj^ and pro- 

 matter. HaUSer has studied the latex globule tein material. {From 



by microdissection methods and finds it to ' ' 

 consist of at least four layers (Fig. 89) three of which are of 

 hydrocarbons which increase in polymerization from the inner, 

 less viscous, ether-soluble core to the outer, more viscous gel 

 which is insoluble in ether. It was formerly thought, and 

 may yet be true in part if not in whole, that when latex 

 coagulates it is the protein covering of the oil globules that 

 coagulates, causing the globules to adhere, thus forming a con- 

 tinuous, spongelike structure the elastic qualities of which reside 

 in the protein coagulum and not in the oil emulsion as such. 

 (This would be true of a protein stabilized emulsion of any 

 inelastic oil, such as those met with in daily life.) But now 

 it is believed that the elastic properties of rubber reside in the 

 oil itself, owing to the unique structure of the hydrocarbon 



