MECHANICAL PARADOXES. 



on which we depend to bring the cream to the 

 top. But this is so small a force to separate 

 so intimate a mixture that it takes many hours 

 before even a partial separation has taken 

 place. 



If we could make the eighteen ounces of 

 cream weigh eighteen pounds, and so with the 

 twenty ounces of water, the floating power 





FlQ. 23.-ACTION OF CREAM SEPARATORS. 



of the former would be equal to the pressure of 

 two pounds, and its small particles would 

 quickly rise to the surface. 



Practically this is what is done by the 

 centrifugal separator, of which a simple form 

 as arranged for laboratory work is shown in 

 Fig. 23. A frame, with about six or ten arms, 

 is arranged to be made to rotate horizontally 

 with great rapidity by a simple hand-wheel 



9 6 



