EDIBLE FATS AND OILS. 



141 



the fin me in such a way as to collect 110 cc of distillate in as nearly thirty 

 in hint os as possible. 



Mix this distillate, filter through a dry filter, and titrate 100 cc with the 

 standard barium-hydroxid solution, using 0.5 cc of phenolphthalein as indicator. 

 The red color should remain unchanged for two to three minutes. 



Increase the number of cubic centimeters of tenth-normal alkali used by one- 

 tenth, divide by the weight of fat taken, and multiply by 5 to obtain the 

 Reichert-Meissl number. Correct result by the figure obtained In a blank 

 experiment. 



(b) LEFFMAN AND BEAM METHOD. 



f ' (1) PREPARATION OF REAGENTS. 



(a) Acid, standard barium hydroxid, indicator, and pumice stone. Prepare 

 ! as in the previous method. 



FIG. 8. Apparatus for the distillation of volatile acids. 



(5) Olycerol-soda solution. Add 20 cc of the sodium-hydroxid solution used 

 In the previous method to 180 cc of pure concentrated glycerol. 



(2) DETERMINATION. 



Add 20 cc of the glycerol-soda to 5 grams of the fat in a flask, weighed as in 

 the previous method, and heat over a naked flame or hot asbestos plate until 

 complete saponification takes place, as is shown by the mixture becoming 

 perfectly clear. If foaming occur, shake the flask gently. 



Add 135 cc of recently boiled water, drop by drop, at first, to prevent foam- 

 ing, and 5 cc of the dilute sulphuric-acid solution, distil without previous melting 

 of the fatty acids, and titrate the volatile acids as in the previous method, 

 correcting results by the figure obtained in a blank experiment 



