IXl SACCHARINE PRODUCTS 131 



26 REDUCING SUGARS.— TENTATIVE. 



Determine either as dextrose or invert sugar as directed under VIII, 50, 51, 



52, 54, or 21, 23, 25, 36 or 39. 



27 STARCH.-TENTATIVE. 



Measure 25 cc. of a solution or uniform mixture, prepared as directed in 1 (b), 

 (representing 5 grams of the sample) into a 300 cc. beaker, or introduce 5 grams of 

 the finely ground sample (previously extracted with ether if the sample contains 

 much fat) into the beaker, add sufficient water to make the volume 100 cc, heat 

 to about 60°C. (avoiding if possible gelatinizing the starch) and allow to stand 

 for about an hour, stirring frequently to secure complete solution of the sugars. 

 Transfer to a stout wide-mouthed bottle, rinse the beaker with a little warm water, 

 cool, add an equal volume of 95% alcohol, mix, and allow to stand at least an hour. 

 Centrifugalize until the precipitate is closely packed on the bottom of the bottle 

 and decant the supernatant liquid through a hardened filter. Wash the precipi- 

 tate with successive 50 cc. portions of 50% alcohol by centrifugalizing and decant- 

 ing through the filter until 3 or 4 drops of the washings give no test for sugar with 

 alphanaphthol as described under 68. Transfer the residue from the bottle and 

 the hardened filter to a large flask and determine starch as directed under VIII, 



60. 



ETHER EXTRACT IN CONFECTIONERY. 



28 Continuous Extraction. — Tentative. 



(1) Measure 25 cc. of a 20% mixture or solution, prepared as directed under 1 

 (b), intoa very thin, readily frangible, glass evaporating shell {Hofmeister Schalchen), 

 containing 5-7 grams of freshly ignited asbestos fiber; or (2) If impossible to ob- 

 tain a uniform sample, weigh 5 grams of the mixed finely divided sample into a 

 dish, and wash with water upon the asbestos in the evaporating shell, using, if neces- 

 sary, a small portion of the asbestos fiber on a stirring rod to transfer the last traces 

 of the sample from the dish to the shell. Dry to constant weight at 100°C., cool, 

 wrap loosely in smooth paper, crush into rather small fragments between the fin- 

 gers, transfer carefully the crushed mass, exclusive of the paper, to an extraction 

 tube or a fat extraction cartridge. A thin lead disk (bottle cap) may be substituted 

 for the Schalchen. The disk may then be cut into small pieces and placed in the 

 extraction tube. Extract with anhydrous ether or petroleum ether (b. p. 45°-60''C. 

 and without weighable residue) in a continuous extraction apparatus for at least 25 

 hours. In most cases it is advisable to remove the substance from the extractor 

 after the first 12 hours, grind with sand to a fine powder, and re-extract for the re- 

 maining 13 hours. Transfer the extract to a tared flask, evaporate the solvent, dry 

 to constant weight in an oven at lOO'C. 



29 Roese-Gottlieb Method. — Tentative. 



Substances such as butter-scotch, invariably yield extremely inaccurate results 

 by the above method. In such cases introduce 4 grams of the material, or an amount 

 of a uniform solution equivalent to this amount of the dry substance, into a Rohrig 

 tube or similar apparatus, make up to a volume of 10 cc. with water, add 1.25 cc. 

 of concentrated ammonium hydroxid and mix thoroughly. Add 10 cc. of 95% alco- 

 hol and mix. Then add 25 cc. of washed ether and shake vigorously for half a min- 

 ute; then add 25 cc. of petroleum ether (b. p. below 60°C.), and shake again for 

 half a minute. Allow to stand for 20 minutes or until the separation between the 



