1006 FOODS AND FOOD ADULTERANTS. 



he obtained 1.3 per cent caffeine from a tea known to contain 3.78 per cent. 

 Boiling alcohol was then used and the rest of the caffeine was obtained. Ex- 

 periments were made to determine whether caustic lime decomposed caf- 

 feine. By experiment he determined that caustic lime does not decompose 

 caffeine under the conditions obtaining in analysis, but that lime exerts a 

 restraining influence on the extractive power with chloroform. Complete 

 extraction of caffeine was obtained with boiling chloroform when magnesia 

 was used. Pharm. J. Trans., March 1891, 882. 



PAUL and COWNLEY. Five grams of powdered tea are moistened with hot water, 

 well mixed with 1 gram of calcicum hydrate, and the whole dried on the 

 water bath. The dry residue is then transferred to a small percolating appa- 

 ratus and extracted with strong alcohol. The clear liquor is evaporated to 

 remove the alcohol and the remaining water solution, which amounts to about 

 50 cc, is mixed with dilute sulphuric acid which separates traces of lime and 

 partially decolorizes the liquid. After filtering it is transferred to a sepa- 

 rator and well shaken with chloroform, about 200 cc, in five to six successive 

 portions. The united chloroform solutions are then placed in a separator 

 and shaken with very dilute sodium hydrate. This renders the caffeine quite 

 colorless. The chloroform is then distilled off and the caffeine weighed. 

 Phar. J. Trans., [3], 908, 417. 



PATROUILLARD, C. Fifteen grams tea are extracted with boiling water until com- 

 pletely exhausted. The liquid is filtered, evaporated to the consistence of 

 an extract, mixed with 2 grams calcined magnesia and 5 grams powdered 

 glass, and dried, The residue is ground to powder, extracted three or four 

 times with 60 cc of ether and this solvent then distilled oft". The crystals 

 of caffeine obtained are redissolved in chloroform and recrystallized. Chem. 

 Ztg. No. 9, Feb. 26, 1880; Chem. News, 42, 259. 



PELIGOT. Make an aqueous extract of the tea, precipitate with lead acetate, add 

 ammonium hydrate, andheat. Filter, pass hydrogen sulphide into the liquid, 

 and filter again. Evaporate to a proper consistency and allow the caffeine 

 to crystallize. This chemist determined the caffeine in exhausted tea leaves 

 by means of a standard tannin solution, but does not give the details of his 

 method. Zeitsch f. anal. Chem., 4, 207. 



SCHWAKZ, M. H. Exhaust the tea with boiling acidulated water, neutralize with 

 lime, evaporate to dryness, and exhaust the residue with ether. Evaporate 

 collect, and weigh the caffeine. Bull. Soc. Chim. de Paris Aug. 5, 1876, 3; 

 Chem. News, 34, 94. 



SMITH, E. D. Coarsely powdered coffee (0.65 gram) is mixed with 0.13 gram mag- 

 nesia, boiled 15 minutes with 150 cc water, filtered, and the filtrate made up 

 to 300 cc by percolation. The filtrate is evaporated to 20 cc and the residue 

 treated with 120 cc strong alcohol, transferred to a filter, and washed with 

 alcohol. The alcohol is then drawn off and the residue dissolved by gradual 

 addition of small quantities of water. This water solution is extracted three 

 times with 25 cc chloroform. The chloroform is distilled off and the caffeine 

 dried and weighed. Chem. Centrbl. 1887, 1270, 1271 ; Zeit. oesterreich. Apoth., 

 Ver., 41, 359. 



SNYDER, HAKUY. Author states that the albuminoids of tea are almost entirely in- 

 soluble in hot water. He extracts the powdered sample with four or five 

 portions of hot water, collects the residue on a filter (S. & S. No. 589), and 

 transfers filter and contents to a digestion flask, and determines the nitrogen 

 by the Kjeldahl method. Total nitrogen in the sample (as determined by 

 Kjeldahl method for alkaloids), less nitrogen of the insoluble portion, gives 

 the alkaloidal nitrogen from which the caffeine may be determined. See 

 Kozai's article on teas, which gives the distribution of the nitrogen, page 

 879, Journ. Anal. Chem., 4, 443. 



