BUTTER-MAKING 229 



Centrifugal creaming 



In recent years, the centrifugal cream separator has taken the 

 place of the older gravity methods except where butter is made 

 on the farm, and in many cases even there. The action of 

 the centrifugal separator is dependent on the same principle as 

 the separation by gravity, e.g. the difference in specific gravity 

 of the fat and milk-serum, but in the case of the separator the 

 force is increased many fold by the centrifugal force of the 

 rapidly revolving bowl. As the milk passes through the bowl, 

 the heavier milk-serum is thrown to the outside of the column 

 while the fat globules remain at the center. The cream may 

 then be removed" through one outlet at the center and the skim- 

 milk from another at the outer edge of the bowl. While the 

 various makes of machines differ greatly in style and size, the 

 essential principle is the same in them all. With the possible 

 exception of the Babcock test, no one invention has done more 

 to revolutionize dairy practices, especially butter-making, than 

 has the development of the modern cream separator. This 

 method has many advantages over the older gravity methods, 

 the more important being as follows: (1) More complete sep- 

 aration of the butter-fat. Many machines will not leave over 

 .01 of 1 per cent of fat in the skim-milk. (2) The thickness of 

 the cream may be regulated to suit the purpose for which it is 

 to be used. (3) The cream may be obtained fresh and of much 

 better quality. (4) Saving in time and labor. (5) The fresh 

 skim-milk is available for stock-feeding. (6) Certain impurities 

 are removed through the separator slime. 

 Development of the centrifugal separator. 



The first practical separator of the centrifugal type was 

 invented by Gustaf de Laval, of Sweden, about 1879. The 

 result of his invention led to the hollow bowl machine with 

 continuous inflow for the whole milk and outflow for the cream 

 and skim-milk. While in all the modern separators the principle 



