38 



CATECHU (HAGERS METHOD}* 



Small quantities of this substance can not be detected with certainty. Boil an 

 extract of tea (1 gram per 100 cc of water) with an excess of litharge and filter; 

 the filtrate should be clear. To a portion of the filtrate add a solution of silver 

 nitrate. In the presence of catechu a yellow flocculent precipitate is formed, which 

 rapidly becomes dark. Under the same conditions pure tea gives a slight grayish 

 precipitate of metallic silver. The w r riter suggests agitating the tea extract with ether, 

 evaporating the ether extract to dryness after shaking with bone char to decolorize, 

 and testing the residue with concentrated sulphuric acid for the presence of catechin, 

 which gives a deep purple coloration. Blyth & states that any amount present to the 

 extent of 3 per cent or over is shown by precipitating an infusion of the tea with a 

 slight excess of neutral lead acetate, filtering, and adding a little ferric chlorid 

 (dilute). If catechu be present there is a bright-green color, and ultimately a pre- 

 cipitate of a grayish-green color. The same infusion filtered from the lead precipi- 

 tate gives a copious precipitate with silver nitrate. 



CAMPECHY WOOD.c 



Eder exhausts 1 gram of tea with 100 cc of boiling water and adds chromate of 

 potash, which gives a blackish-blue color if the wood is present. 



CHICORY. 



Chicory can be most readily and certainly identified in mixtures by means of the 

 microscope. The microscopic appearances of coffee and chicory are shown in Bul- 

 letin 13. ^ Chemical methods for its detection are given by Wittstein, e Franz,/ 

 and Hiepe.S' 



SANDERS WOOD IN COCOAS 



Sometimes added for masking the addition of starch. Two to three grams are 

 shaken with 10 cc of absolute alcohol. With pure cocoa the alcohol remains colorless 

 or colored only a slight yellow, and gives a white precipitate with sodium hydroxid 

 and no reaction with ferric chlorid. The filtered alcoholic extract from sanders wood 

 or cocoa mixed with the latter is, on the other hand, colored, and gives with dilute 

 sodium hydroxid an intense violet color. Should the wood have been previously 

 exhausted this coloration is less pronounced. Ferric chlorid also yields a deep 

 violet color with the unexhausted wood, but in the case of exhausted wood this 

 reaction is only to be obtained by allowing a drop of the reagent to run on to the 

 surface of the alcoholic extract. A violet ring is then formed, which disappears on 

 shaking. Acetone may replace the alcohol. 



TURMERIC IN RHUBARB. * 



Anselmier shakes 0.1000 gram of the powder with 20 drops of olive oil for one 

 minute. One drop of the mixture is then placed on white filter paper, when a 

 characteristic yellow ring is formed should turmeric be present. The ring given 

 by rhubarb can not be mistaken for the turmeric ring. 



aPharm. Central-Halle, 1879, 258. 

 & Blyth, Foods, 1896, p. 423. 

 cBujard and Baier, Hilfsbuch, p. 225. 



tf U. S. Dept. Agr., Bureau of Chemistry, Bui. 13, Part 7, Tea, coffee, and cocoa 

 preparations, plates 42, 43, and 45. 

 <? Dingier' s polytech. J., 211, 78. 

 /Arch. Pharm., (3) 8, 298. 

 Q Moniteur scientifique, (3) 10, 1339. 

 ^Zts: offentl. Chem., 1902, 203. (R. & L.) 

 iChem. Ztg. Rep., 1904, 80. 



