54 



ASH. 



Char a convenient weight of the original sample (from 2 to 5 grams) in a platinum 

 dish, in a muffle, at the lowest possible temperature until free from carbon. If carbon 

 free aish can not be obtained owing to its fusibility, exhaust charred mass with water 

 and proceed as under ash, Bulletin 107, page 38. 



CRUDE FAT (ETHER EXTRACT). 



Extract a convenient quantity of the product (from 4 to 5 grams) as dried in the 

 determination of moisture with anhydrous, alcohol-free ether, for 24 hours (with fine 

 flour the addition of an equal weight of clean dry sand is frequently necessary). Dry 

 the extract at the temperature of boiling water until it ceases to lose weight. 



NOTE. lodin numbers should only be obtained upon the ether extract after purifi- 

 cation by solution in petrolic ether, but are best made upon the petroleum ether 

 extract. 



SOLUBLE CARBOHYDRATES (AS DEXTROSE). 



Weigh 16 grams of flour into a 500 cc flask. Add 200 cc of water. Shake occasion- 

 ally during one-half hour. Filter through a dry folded filter. To 50 cc of the filtrate 

 ado! 5 cc of concentrated hydrochloric acid. Place the flask in water and invert at 

 70 C. for ten minutes. Cool, neutralize, and bring to 100 cc. Filter. Determine the 

 reducing sugars with Fehling solution, by the official method, as described in Bulletin 

 107, calculating the reducing sugars as dextrose. 



CRUDE FIBER. 



Determine the crude fiber in 2 grams of flour by the official method (Bui. 107), 

 filtering through linen in a Biichner funnel. 



DETERMINATION OF MOIST GLUTEN. 



Dough lip 30 grams of flour with 18 cc of water conveniently in an 8-ounce mortar. 

 Weigh off 16 grams of dough equivalent to 10 grams of flour. Place in water at room 

 temperature for one hour and carefully wash out the starch over bolting cloth or a fine 

 horsehair sieve. After expressing all globules of water, weigh the moist gluten upon 

 a watch glass. Dry in a desiccator for 24 hours and complete drying in water oven. 



ACIDITY IN FLOUR. 



Weigh 18 grams of flour into a 500 cc Erlenmeyer flask and add 200 cc of distilled 

 water, previously freed from carbon dioxid by boiling in tin. Place the loosely stop- 

 pered flask in a water bath kept at 40 C. for 10 minutes, shaking repeatedly. Remove 

 the flask and allow it to stand, with occasional shaking, at room temperature for one 

 hour. Filter upon a dry folded filter, rejecting the first 10 cc and receiving the suc- 

 ceeding 100 cc in a graduated flask. Titrate the filtrate with twentieth-normal sodium 

 hydroxid, using carefully neutralized phenolphthalein in alcohol as an indicator. 

 Each cubic centimeter of twentieth-normal sodium hydroxid represents 0.05 per cent 

 of acidity as lactic acid. 



NOTE. Results obtained with flour at temperatures of 15, 20, and 25, respectively, 

 indicate that the acidity in the solution increases with the temperature. The method 

 outlined seems to give the maximum acidity. 



TOTAL NITROGEN IN FLOUR. 



Determine the total nitrogen in 2 grams of flour according to the official method, 

 preferably the Gunning method, Bulletin 107, page 7. The nitrogen times 6.25 gives 

 total proteids. 



GLOBULIN AND ALBUMEN (EDESTIN AND LEUCOSIN) AND AMID NITROGEN. 



Weigh 5 grams of flour into a 500 cc Erlenmeyer flask. Add 250 cc of sodium chlorid 

 solution 1 per cent. Stopper and shake thoroughly. Let stand, with occasional shak- 

 ing, for three hours. Filter on dry paper. Evaporate 100 cc of the filtrate to small vol- 

 ume in a Kjeldahl digestion flask with 5 cc of sulphuric acid. Add remainder of the 



