112 Milk and Its Products. 



been the chief factor iu revolutionizing methods of 

 butter- making. By its greater efficiency it has pre- 

 vented otherwise unavoidable losses, and b}' its greater 

 economy of labor it has rendered possible the devel- 

 opment of a profitable industry in many localities 

 Tvhere it would have been otherwise impossible. 



In separating cream in a centrifugal machine, the 

 centrifugal force generated in a rapidly revolving 

 bowl is made to take the place of the force of grav- 

 ity acting upon the milk at rest in a vessel. The 

 amount of force generated is so much greater than 

 the force of gravity that the separation of the par- 

 ticles of fat is much more rapid and much more 

 complete. The force, however, acts in a horizontal 

 instead of a vertical direction. In 1877, a patent was 

 granted to Le Feldt & Lentsch for a machine to sepa- 

 rate milk by centrifugal force. This first centrifugal 

 separator consisted merely of a series of buckets hung 

 upon arms swinging from a central axis. When the 

 machine was at rest the buckets assumed a vertical 

 position, but in motion they were thrown out horizon- 

 tally from the arms. The milk was placed in these 

 buckets, the machine set in motion until the cream 

 was separated from the skimmed milk, and when the 

 machine was allowed to come to a stand- still the 

 buckets assumed a vertical position, and the cream 

 was removed from the top in the same way that it 

 was skimmed from any other vessel. From this was 

 evolved a machine consisting of a revolving bowl 

 or drum in which the separation takes place, with 

 arrangements for removing the skimmed milk and 



