88 QUESTIONS AND ANSWERS 



What is meant by the Reichert-Meissl number? 



It means the number of c. c. -^ alkali required 

 to neutralize the volatile acids from 5 grams of the 

 fat. 



How is the Reichert-Meissl number determined? 



Five grams of the fat are placed in a clean, dry- 

 flask of 300 c. c. capacity, 10 c. c. of 95 per cent 

 alcohol added, and 2 c. c. of a saturated aqueous 

 solution of sodium hydrate. Place a funnel in 

 the neck of the flask and heat on the water bath 

 with occasional shaking until saponification is com- 

 plete, when the solution will be free from fat-glob- 

 ules and perfectly clear. Then remove the funnel 

 and continue heating over the bath to dryness. 

 Add 135 c. c. of water and warm on the water bath 

 with shaking until the soap is dissolved. Cool and 

 add a few small pieces of pumice stone, to prevent 

 lumping while boiling, and 5 c. c. of dilute sul- 

 phuric acid (200 parts of acid to 1,000 parts water). 

 Connect the flesk with a condenser and distill oflF 

 no c. c. in about 30 minutes. Titrate the entire 

 distillate with tenth-normal alkali, using phenol- 

 phthalein as indicator. The number of cubic cen- 

 timeters of tenth-normal alkali required express 

 what is called the Reichert-Meissl number. 



How does the Reichert-Meissl number for butter 

 and for oleomargarine differ? 



The size of the Reichert-Meissl number for oleo- 

 margarine usually depends to a great extent upon 

 the per cent of butter present in the oleomargarine. 

 This number is not often more than 5 for oleomar- 

 garine and rarely less than 24 for butter. The 



