CREAMING 



sarily show the quality of the milk, since the fat 

 may be removed as cream and sufficient water 

 added to restore the normal specific gravity. 



Quevenne's lactometer, commonly used 

 with milk, is graduated from 15 to 40, 

 and this reading is converted into specific 

 gravity by adding 1,000 and dividing the 

 sum by 1,000, or, stated differently, by 

 prefixing to the reading the figures i.o. 



Creaming. The size of the fat glob- 

 ules materially influences the rapidity and 

 thoroughness with which they rise. The 

 larger the globules, the greater the up- 

 ward pressure. This upward pressure of 

 the fat globules of various sizes is in pro- 

 portion to their volume, and this is in 

 proportion to the cube of their diameter. 

 If we have two spheres, one 4 inches in 

 diameter, the other 2, the cubes of their 

 diameters will be 64 and 8, so that the 

 upward push of the larger one will be 

 eight times as great as of the smaller one. 

 They are retarded in this upward motion 

 by the pressure of the liquid in propor- 

 tion to the surface of the globules, which 

 are to each other as the squares of their 

 diameter. Their squares will be 16 and 4, 

 and the retarding friction of the liquid 

 through which the globules must rise will only be four 

 times as great on the larger one as on the smaller one, 

 so that the greater the difference in size, the easier and 

 more rapidly the larger ones rise to the surface. 



COMBINED 

 QUEVENNE'S 

 LACTOMETER 



AND 

 THERMOMETER 



