910 FOODS AND FOOD ADULTERANTS. 



ainined for in the ash by the usual qualitative methods tor the de- 

 tection of lead and chromium. The asli should also be examined for 

 copper, and in the ease of moist preparations of coffee preserved in tin 

 cans, both tin and copper should be searched for. Azo-colors are de- 

 tected as follows: 



Azo-colors are detected l>y treating the beans with strong alcohol, evaporating the 

 solution to dryness, and treating the residue, with water. This solution will give 

 the characteristic reactions of these dyes. 



It is preferable, when possible, to detach the facing by shaking- the 

 coffee with cold water. The sediment may be examined chemically or 

 microscopically. Lead, tin, copper, and arsenic are the only objection- 

 able metals liable to be present in coffee or its preparations. The ash 

 should be examined for these metals. 



Chicory. One of the common adulterants of coffee is the prepared 

 root of the chicory plant, Cychorium intybus. There are .several chem- 

 ical methods for the detection of chicory, depending upon positive and 

 negative tests. Ground chicory when thrown on cold water sinks 

 quickly, coloring the water, and is soon softened, whereas ground 

 roasted coffee floats, imparting no color. Chicory is easily bleached by 

 chlorinated soda (labarraque solution); coffee is but slowly affected by 

 this bleaching agent. The coloring 1 matter of chicory is not precipi- 

 tated by iron salts, while that of coffee is colored green and is partially 

 precipitated. G. C. Wittstein 2 employs the following method: 



Boil 30 drops of the coffee infusion in a test tube with 2 drops of con- 

 centrated hydrochloric acid; add 15 drops potassium ferrocyanide solu- 

 tion (1 part of the salt to 8 of water), and again boil until the liquid 

 becomes a dark green ; add 6 drops of potassium hydroxide solution and 

 boil ; if chicory is present the liquid will become brown and murky, 

 v otherwise a precipitate will separate and settle to the bottom of the 

 tube, leaving the supernatant solution of a light-yellow color. 



A. Franz 3 states that copper acetate gives a greenish- brown precipi- 

 tate with coffee infusions and a dark-red brown precipitate with chicory. 

 With coffee the supernatant liquid is greenish and with chicory red 

 brown. 



Hiepe 1 tests for chicory as follows: Ignite 25 grams of the sample 

 and determine the amount of chlorine present in the ash. Coffee con- 

 tains 0.03 per cent chlorine, and chicory as high as 0.28 per cent. Kor- 

 nauth 5 gives the maximum and minimum chlorine content of cotl'ee as 

 respectively 0.00 per cent and 0.15 per cent. 



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 Plates XLII, XLIII, and XLV. 



'Ding. Polyt. Jonrn., 211,78; Jahresl.. d. ('hem., 1X71. IOC!. 



2 Ding. I'olyt. Journ., 215, 81 ; Am. Chemist. 6, L'L'O. 



'Arch. Pharni. [3], 8,2!K; Jahresb. d. Cheni., 1S7IJ. 1021. 



'Monit. -in- Scientific [3], 10, 1331); Jahresl,. .1. ( 'hem., isso, 1>0. 



f 'Mitt. a. d. 1'liarm. lust. 11. Lal>. f. Angew. Cheni. Krlangrn. Heft 15, 1 to .M!. 



