DAIRYING INTERESTS. 189 



from the inilk in much the same way. The cream or butter 

 particles of new milk are the lightest part of the fluid, and 

 rise to the surface of their own gravity when milk is set 

 in pans. And this separation of cream 

 particles is completed, almost instantly, 

 by the machine, the revolving sepa- 

 rator of which is moving at the rate of 

 from 3000 to 5000 revolutions per minute, 

 and separating 25 to 250 gallons per 

 hour by hand, steam, or other power. 

 This contrivance is a really scientific 

 conception, long in use in laboratory 

 practice, and founded on an ac- 

 quaintance with the fat globules 

 in !nilk,andaknowledgeof their 

 different specific gravity from 

 the liquid in which they tioat, 

 and a further knowledge of 



Hand Cream Separator. what must be the behaviour 



of a mixture of such globules and such liquid when 

 subjected to centrifugal force. In operation, the milk 

 runs in a steady stream into the top of the separator, 

 and the heavier portion in reality the skimmed milk 

 is thrown to the outside of the machine, aud is discharged 

 in a steady stream. The cream meanwhile is gathering 

 in an inner layer, and is discharged from another outlet. 

 Amongst the advantages of the system, it is more 

 cleanly, everything heavier than cream is extracted 

 promptly, and very curious substances are thus seen to 

 be present in milk, whether coming from the poor con- 

 dition of the animals, from poverty of feed, from dirty 

 milking, bad water, exposure to excessive cold or rain, or 

 other causes, need not be followed at this stage. The 

 evils of contact from flies, dust, &c., that can scarcely be 

 avoided when milk is set out to get the cream to rise in 

 pans, are also overcome. 



From Cream to Butter. The whole of tho operations, 

 from the time of milking to the production of cream, are 

 accomplished in tho factories, as a rule, during the cool of 

 the morning a change, indeed, from tho time when the 



