106 Milk and Its Products. 
is concerned, in diluting it with 25 per cent of warm 
water, this dilution cannot be regarded as a sub- 
stitute for setting without dilution in ice water, and 
it has the further disadvantage of requiring in- 
creased tank capacity. 
Centrifugal separation.—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 gravity 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 particles of fat is much more 
rapid and much more complete. The force, how- 
ever, acts ina horizontal instead of a vertical direc- 
tion. In 1877, a patent was granted to Le Feldt & 
Lentsch for a machine to separate milk by centrif- 
ugal 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 horizontally from 
the arms. The milk was placed in these buckets, 
the machine set in motion until the cream was sepa- 
rated 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 re- 
moved 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 
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