1422 FOODS AND FOOD ADULTERANTS. 



in 100 grams of oil or fat), or as acid value (milligrams of potassium 

 hydroxid required to saturate the free acids in 1 gram of fat or oil). 

 1 cc decinormal alkali := 0.0282 gram oleic acid. 



DETERMINATION OF VOLATILE ACIDS. 



See methods for dairy products, Bulletin 64. 



Benedikt proposed to determine the hydroxy acids and alcohols by 

 the use of acetic anhydrid (C 2 H 3 O) 2 O, as illustrated in the following 

 reaction : b 



C 17 H 32 (OH)COOHH-(C 2 H 3 0) 2 0-C 17 H 32 (OC 2 H 3 O)COOH+HC 2 H 3 O 2 



He proposed to work on the fatty acids, but the process was modi- 

 fied by Lewkowitsch, c in that he works on the oils or fats directly, 

 which gives more exactly the true content of hydroxy acids. 11 



The procedure is as follows: 



Boil the oil or fat with an equal volume of acetic anhydrid (C 2 H 3 O) 2 O 

 for two hours and pour the mixture into a large beaker containing 

 500 cc of water and boil for half an hour. To prevent bumping, a slow 

 current of carbonic acid is passed into the liquor through a finely drawn- 

 out tube reaching nearly to the bottom. Allow the mixture to sepa- 

 rate into two layers, siphon off the water, and boil the oily layer with 

 fresh portions of water until it is no longer acid to litmus paper. 



The acetylated fat is then separated from the water and dried and 

 filtered in a drying oven. 



Weigh from 2 to 4 grams of the acetylated fats into a flask and 

 saponify with alcoholic potash, as in the determination of saponifica- 

 tion equivalent. If the distillation process is adopted, it is not neces- 

 sary to work with a standardized alcoholic potash solution. In case 

 the filtration method is used, which will be found much shorter, it is 

 necessary that the alcoholic potash should be measured exactly. 



In either case evaporate the alcohol after saponification and dissolve 

 the soap in water. Now, two procedures are possible either distilla- 

 tion or filtration. 



DISTILLATION PROCESS. 



Acidify with dilute sulphuric acid (1-10) and distill the liquid as in 

 the Reichert test. As several hundred cubic centimeters must be dis- 

 tilled, either a current of steam is run through or portions of water 



a Lewkowitsch, Jour. Soc. Chem. Ind., 1897, 10, 503-506; Benedikt, Analyse der 

 Fette u. Wach, 3d ed., p. 146; Allen, Com. Org. Anal., 3d ed., 2, pt. 1, pp. 66-67. 

 b Benedikt and Lewkowitsch, Oils, Fats, and Waxes, p. 127. 

 c Jour. Soc. Chem. Ind., 1897, 16, 503. 

 d J, Lewkowitsch, Jour. Soc. Chem. Ind., 1890, 9, 846. 



