MILK AND ITS PRODUCTS 



195 



11. How many cows would be required where the shallow-pan 

 syst om is used, to supply as much cream as would be secured from 6 

 cow s when the centrifugal separator is used ? 



12. Why is butter yellow in summer, and much lighter in color 

 in v inter ? 



13. What is a farrow cow ? Why is cream from her milk likely 

 to 1 e hard to churn? 



1 4. What is the leading dairy product in your region ? 



15. Is more or less of the butter in your region made in factories 

 tha i formerly? 



16. What butter or cheese factories are there in the region? 



1 7. What dairy products are sold in your local stores ? Where 

 do ' hey come from ? 



1 8. The following table gives results for 1909. Using data given 

 in t lis chapter, fill in the blanks. 



LABORATORY EXERCISES 



COMPOSITION OF MILK 



15. Butter-fat. Examine some milk under the microscope, using 

 preferably a one-sixth objective, and make drawings of the fat 

 globules showing the variations in size. 



16. Casein of Milk. This part of milk is precipitated by dilute 

 acids. Place 10 c.c. of skim-milk in a 200 c.c. beaker and add 90 

 c.c. of water at a temperature of 100 F. Immediately add 1.5 c.c. 

 of a 10 per cent solution of acetic acid. Let it stand 20 minutes 

 with occasional stirring. Filter, using ordinary filter paper, saving 

 the filtrate in another beaker. The residue on the paper is the casein. 

 The albumin, sugar, and ash are in the filtrate. 



17. Albumin of Milk. Heat the filtrate from the above rapidly, 

 and boil until the solution can be filtered with a clear filtrate. Filter 



