DAIRY LABORATORY GUIDE 



73 



6. Calculate the solids not fat (S. N. F.) and total solids 

 (T. S.) by the following formulas. The total solids include 

 the solids not fat plus the B. F. 



S. N. F. = JL + .2f 



T. S. = ML + 1.2f 



in which L is the lac. reading at 60 F., and / the percentage of fat 

 in the sample. 



7. Calculate the percentage of adulteration. 



Formula : 



S.N.F. X 100 



100- = percentage of adulteration. 



9 



Data: 



Application: 1. What is the Sp. Gr. of normal cow's 

 milk? Why is it necessary to make a correction in the lac- 

 tometer reading when the temperature varies? What is the 

 effect of heating upon the Sp. Gr. of the sample? Of cooling? 



2. What are the solids not fat in milk? Total solids? 



3. What is the legal standard for each in the United 

 States? 



4. A sample of 4% milk at 60 F. shows a lactometer 

 reading of 31. What is the percentage of S. N. F. in the 

 sample? Calculate the percentage of adulteration. 



5. Find the S. N. F. in a sample of 3.5% milk at 28 F., 

 when the lactometer is 34. 



6. If milk has a Sp. Gr. of 1.032 at 60 F., what will be 

 the Sp. Gr. at 70 F.? At 50 F.? 



