318 METHODS OF ANALYSIS [Chap. 



the ether, dry first at 100°C. and finally to constant weight at 110°C. Determine 

 the nitrogen in the weighed extract, as directed in I, 23, digesting in the same flask 

 used for the extraction. Calculate the parts of nitrogen per 100 parts of non-vola- 

 tile ether extract. If desired, crude piperin may be calculated from the nitrogen 

 by multiplying by 20. 3G. 



9 VOLATILE AND NON-VOLATILE ETHER EXTRACT^.— TENTATIVE. 



Extract 2 grams of the ground material for 20 hours in a continuous extrac- 

 tion apparatus with anhydrous ether [VIII, 9]. Transfer the ethereal solution to 

 a tared capsule and allow to evaporate at room temperature. Let stand for 18 

 hours over sulphuric acid and weigh the total ether extract. Heat the extract 

 gradually and then to constant weight at 110°C. The loss is volatile ether extract; 

 the residue, non-volatile ether extract. 



10 ALCOHOL EXTRACT^.-TENTATIVE. 



Place 2 grams of the sample in a 100 cc. flask and fill to the mark with 95% alcohol 

 by volume. Stopper, shake for 8 hours at 30 minute intervals and allow to 

 stand for 16 hours longer without shaking. Filter the extract through a dry 

 filter, evaporate a 50 cc. aliquot of the filtrate to dryness in a flat-bottomed dish 

 on a water bath and heat to constant weight at 110°C. 



11 COLD-WATER EXTRACT.-TENTATIVE. 



(For ginger.) 



Place 4 grams of the sample in a 200 cc. graduated flask, add water to the mark, 

 shake at 30 minute intervals during 8 hours and let stand 16 hours longer with- 

 out shaking. Filter and evaporate a 50 cc. aliquot of the filtrate to dryness in a 

 flat-bottomed, metal dish. Dry to constant weight at 100°C. 



1 2 COPPER-REDUCING SUBSTANCES BY DIRECT INVERSION.— TENTATIVE. 



Extract 4 grams of the sample with 5 successive portions of 10 cc. of ether on a 

 filter that will retain completely the smallest starch granules. After the ether 

 has evaporated, wash with 150 cc. of 10% alcohol by volume. 



Owing to the formation of a glutinous mass which clogs the filter, it is not possible 

 to wash samples of Batavia cassia with water or dilute alcohol. Therefore all pre- 

 liminary washing is best omitted in determinations made on all varieties of cassia, 

 as well as on cassia buds and cinnamon. 



Carefully wash the residue from the paper into a .500 cc. flask with 200 cc. of 

 water, using a small wash bottle, and gently rubbing the paper with the tip of the 

 finger. Hydrolyze and determine the copper reducing material as directed under 

 VIII, 60. Express the result in terms of starch. 



13 STARCH.— TENTATIVE. 



Extract 4 grams of the finely pulverized sample with ether and 10% alcohol by 

 volume, as directed under 12, and determine starch by the diastase method, as 

 directed under VIII, 62. 



14 CRUDE FIBER.— TENTATIVE. 



Proceed as directed under VIII, 68, and remove all ether extractives by suc- 

 cessive washings of the dry fiber with ether previous to weighing. 



