92 QUESTIONS AND ANSWERS 



a few moments. Allow the mixture to stand a few 

 minutes until any remaining fat has collected on 

 the surface. Then draw the water into a flask, being 

 sure that no fat passes through. Again add hot 

 water to the beaker and repeat the washing in the 

 funnel several times, using 15 c. c. of water each 

 time. 



Determine the sodium chlorid in a measured 

 part (10 c. c.) of the liquid by titrating with stand- 

 ard silver nitrate solution, using potassium chro- 

 mate as an indicator, i c. c. -g- silver nitrate solu- 

 tion=.oo5837 grams of salt. 



To determine the total amount of salt divide the 

 total number c. c. of water used by 10 and multiply 

 by .005837. This will give the total number grams 

 of salt in 10 grams of butter. Then, knowing the 

 amount present in 10 grams, it is an easy matter to 

 determine the amount in 100 grams by multiplying 

 by 10. This gives the percentage of salt in the 

 butter tested. 



2. Gray's salt test. A representative lo-gram 

 sample of butter is placed in a small glass dish. 

 The dish is then half filled with boiling water and 

 the mixture of fat and water poured into a 500 c. c. 

 glass flask. The dish is rinsed several times with 

 hot water and each time the rinsings are poured into 

 the flask. The flask is then filled to the 500 c. c. 

 mark with boiling water and thoroughly shalcen. 

 Then allow the contents of the flask to cool and 

 after the fat has collected on top and hardened, 

 measure with a pipette 50 c. c. of the clear solution 

 beneath the fat and place it in a clean glass dish. 

 Fifty c. c. of a potassium chromate indicator is 

 then added and the solution titrated with a standard 



