Grade 



Date 



EXERCISE 20. 



(39) 



Object. — To test butter for percentage of fat. 



Apparatus. — Sample of butter; Babcock test outfit. 



Step 1. Preparing sample. — Put a fair sample into a tightly stoppered 

 bottle. Put the bottle into water at 95° F. and shake thoroughly until 

 melted. Then put the bottle into cold water and shake well until butter 

 becomes of a thick, creamy consistency. From this sample small por- 

 tions may be taken for testing. 



Step 2. Testing. — Weigh 9 grams of butter into each of two bottles gradu- 

 ated to 50 per cent, add 10 cc. of hot water, and about 8.5 cc. of acid. 

 Mix until all the curd is dissolved. Add hot water to bring the fat into 

 the neck of the bottle. Whirl in a centrifuge for five minutes and read. 

 The reading multiplied by 2 will be the correct test. 



1. If butter contains 80 per cent fat what should be the percentage of 

 overrun? 



2. What is the average composition of butter? 



3. What is the percentage of butterfat allowed by law? 



