247] THE MANUFACTURE OF BUTTER 23 



THE EVOLUTION OF THE CREAM SEPARATOR 



The principle upon which the mechanical separation of 

 cream is based is the subjection of substances having dif- 

 ferent specific gravities to centrifugal force. The butter 

 fat in milk has a specific gravity of 0.93, while that of 

 skim milk is 1.035. CH these two substances, therefore, fat 

 is considerably lighter than skim milk. It follows, for this 

 reason, that when milk is placed in a vessel made to re- 

 volve rapidly that the skim milk, which is the heavier con- 

 stituent, is drawn to the outer edges of the mass, while the 

 fat is forced toward the center. In order to separate the 

 fat from the skim milk it is only necessary to tap the 

 cream at the center and the skim milk at the periphery of 

 the vessel. 



Probably the first mechanical device used to separate 

 cream from milk was constructed in Germany by Prof. C. 

 J. Fuchs in 1859. 1 The milk was placed in a glass tube 

 which was made to revolve rapidly. Prof. Fuchs' object 

 does not seem to have been to invent a machine that could 

 be used in dairying and that would eliminate cream-setting, 

 but to construct a device by which the richness of the milk 

 could be tested. 



In 1870 Rev. H. F. Bond, of Massachusetts, separated 

 cream in two glass jars attached to a spindle making 200 

 revolutions a minute. 2 



At the same time this problem was studied in America 

 experiments were tried in Europe, where the names of 

 Lefeldt, Lentsch, Weston, and De Laval are associated 

 with the development and perfection of the centrifugal 



1 First Annual Report of the New York State Dairy Commissioner, 

 p. 96. 



a For the successive steps in the evolution of the separator, see Van 

 Norman, First Lessons in Dairying, pp. 86-7; and H. H. Wing, Milk 

 and its Products, p. 112. 



