68 



THE BOOK OF BUTTER 



speed. It is reported that at one time early in the his- 

 tory of centrifugal separators, before the machines were 

 perfected, a separator bowl burst at Hazelton, Kansas, 

 and killed seven persons. A few similar accidents have 

 happened before and since because machines are often 

 over speeded. This means that an operator should be well 



acquainted with the machine 

 itself and with the important 

 considerations affecting the sep- 

 aration of milk. In the follow- 

 ing paragraphs are some of these 

 important factors. 



47. Regulation of the fat in 

 the cream. The richness, or 

 the percentage of fat, in cream 

 derived from whole milk by the 

 use of a centrifugal separator is 

 regulated by either a cream 

 screw or a skimmed -milk screw. 

 Two main facts should be re- 

 membered when one sets either 

 of these screws. The first is 

 that the richness of the cream 



FIG. 29. DaLaval power sep- 

 arator. This machine was 

 belt-driven and consisted of 

 a large hollow bowl and a 

 frame for supporting it. This 



' depends on the point in the 



about 600 pounds of milk an 

 hour, and in size was about 

 3 feet high. The bowl was 

 11 j inches in diameter. 



bowl from which it is drawn. 

 The richest cream is drawn 

 from the center of the bowl, 

 and the richness decreases as the distance from the 

 center increases. The other fact is that the smaller the 

 proportion of cream to skimmed-milk, the richer is the 

 cream in fat. The percentage of fat in cream should 

 be regulated according to the use that is to be made 

 of the cream. Ordinarily for churning purposes, the 



