CHAPTEE XXXI 



BUTTER 



"TT^ROM milk," continued Uncle Paul, "we make 

 JT butter and cheese. I have just explained to 

 you in a few words how the ingredients composing 

 them that is, cream and casein are obtained in 

 their separate forms; but further details are now 

 called for, and I will give them to you, beginning 

 with butter. 



"The material necessary for making butter is 

 cream, a fatty substance disseminated through the 

 milk in excessively fine and almost invisible par- 

 ticles. When milk is left undisturbed in a cool place 

 and exposed to the air, these particles of fat rise to 

 the surface little by little and collect there in a layer 

 of cream. An example taken from things familiar 

 to you will explain the cause of this spontaneous 

 separation. 



"Oil, you know, cannot in any way be made to 

 dissolve in water. If a mixture of the two liquids 

 is well shaken, the oil divides into an infinity of tiny 

 globules uniformly distributed, and the whole takes 

 on a whitish tint that looks something like milk. 

 But this condition is only temporary. If you stop 

 heating or shaking the mixture, the oil, the lighter 

 part, comes to the surface, globule by globule, and 



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