48 THE STORY OF MILE! 



cream four times as rich as the milk^ a ^'16% cream.'' 

 So out of 100 lbs. of milk we can take 12}/^ lbs. (1/8) 

 of 32% cream, 25 lbs. (K) of 1G% cream, etc. 



Although the skim milk is really valuable as a food, 

 it is worth but little commercially; the cream contain- 

 ing the butter-fat is the expensive part of the milk, 

 and we must be prepared to pay for the cream all that 

 the milk would have cost. 



Percentage of Butter-Fat. — The '^richness" of cream 

 or milk and their value depend upon the amount of 

 butter-fat in them. So cream or milk is often called 

 ^'30% cream" or '^20% cream" or "4% milk" accord- 

 ing as 30% or 20% or 4% of the fluid is butter-fat ; 30% 

 cream is quite rich; ordinary market cream varies be- 

 tween 18% and 40%, though it may fall below 18%, or it 

 may be sold as a very expensive article as high as 60%. 

 Rich milk may contain more than 6% of butter-fat and 

 skim milk less than 0.1 of one per cent. The average 

 for good whole milk is between 3% and 4J4%- 



For a long time scientists and scientific dairymen 

 were the only ones to speak of milk and cream in terms 

 of percentage of butter-fat. Now, however, people are 

 beginning to realize how valuable a part of the milk 

 the butter-fat is and are paying more attention to the 

 actual percentage of butter-fat in the cream or milk 

 they use. So it is no longer unusual to see a dairyman 

 advertise cream of a certain percentage or to hear a 

 housewife ask for it specifically. 



Standardizing Cream. — For ice cream or for prepar- 

 ing modified milk for babies, it is often desirable to 

 dilute rich cream to a certain lower standard. The 

 following simple steps can be taken to find out how 

 much milk to add for diluting: 



