ILLINOIS STATE DAIRYMEN'S ASSOCIATION. I05 



expensive centrifugal machines when we have cheap gravity machines on 

 the market at the present day. 



The principle of cream separation is a simple one, when we do not 

 take too many details into consideration, but it is certainly very confus- 

 ing when we learn of the statements made by many of the would-be 

 creaming machine promoters. 



At present there are four methods of creaming; the shallow pan, the 

 deep-setting, dilution and centrifugal. It, no doubt, might be interest- 

 ing as well as making it more comprehensive to review the principles of 

 creaming. 



Milk is composed of five constituents, namely: Water, milk, sugar, 

 casein, fat and ash. We have here the five constituents (shows samples) 

 — the water and the casein, the fat and the ash, and this is the milk 

 sugar. The fat is the highest when we put these four together and mix 

 them in with water, we call them milk serum. All these tend to increase 

 the specific gravity or the heft of the milk. The fat tends to lighten it. 



The creaming of milk is merely the concentration of fats. Cream 

 contains all the constituents of milk, in approximately the same per cent 

 except that the fat replaces the water to a certain extent. The composi- 

 tion of cream is influenced by the method and condition of creaming and 

 varies with wide limits. The per cent of fat may vary from 8 to 78 per 

 cent. Ordinarily a mixture containing less than 8 per cent of fat is known 

 as milk, or more than 78 per cent, as butter. 



The fat ir4 milk exists in minute globules suspended in the milk. The 

 size of the globules varies according to breed of cows, the period of lac- 

 tation, the kind of feed and other factors. To illustrate their approxi- 

 mate minuteness, we might state as an average estimate, that there are 

 two million globules in a quart of milk, or, if these globules be laid side 

 by side, 25 would equal the thickness of medium letter paper. The separa- 

 tion of these globules in creaming may be effected in several different 

 ways, but the general principle depends upon the difference in the spe- 

 cific gravity of the fat globules and that of the water containing the 



