DETECTION OF ADULTERATED COFFEE. 909 



tionable. There is not sufficient evidence against chicory to warrant 

 placing it in the list of objectionable substances. Obvious adulterants 

 of coffees are the so-called substitutes molded in imitation of the genuine 

 beans. 



ADULTERANTS AND THEIR DETECTION. 



Facing or coloring. It is not an uncommon practice to treat inferior 

 or damaged coffees by some process for the improvement of their 

 appearance and in imitation of superior grades. Java seems to have 

 been especially subject to this treatment, or rather other coffees are 

 colored in imitation of Java. E. Waller states ] that South American 

 coffees are often exposed to a high, moist heat, which changes their color 

 from green to brown, thus forming imitation Java. Waller also men- 

 tions the use of pigments in coloring coffees. This chemist found one 

 twenty-fourth grain of Scheele's green per one-half ounce of coffee. He 

 also reports the use in the Brooklyn mills of yellow ocher, silesian blue, 

 chrome yellow, burnt umber, Venetian red, drop black, charcoal, and 

 French black. Coffee is polished by rotation in cylinders with soap- 

 stone. 



The following 2 is another method of preparing imitation Javas. Raw 

 coffee, which has been damaged by sea water, is washed, decolorized 

 with lime water, again washed, rapidly dried, and colored by a slight 

 roasting or by means of azo-orange. By this method Santos coffees 

 are converted into imitation Javas. The weight lost is regained by 

 steaming, and then coating the beans with glycerine, palm oil, or vase- 

 line to prevent evaporation. 



Coffees are sometimes faced with Prussian blue or indigo, lead chro- 

 mate, etc. The following list of facing mixtures is from the published 

 investigations of K. Sykora. 3 



(1) Mixture of indigo, lead chromate, coal, and clay. 



(2) (Approximately) 5 parts indigo, 10 parts coal, 4.5 parts lead chro- 

 mate, 05. 5 parts clay, and 15 parts ultramarine. 



(3) (Approximately) 5 parts indigo with some yellow dye, 3 parts 

 coal, 8 parts lead chromate, 82 parts clay, 2 parts ultramarine. 



(4) (Approximately) 12 parts indigo and some yellow dye, 5.5 parts 

 coal, 4.5 parts lead chromate, C.6 parts clay, and 12 parts ultramarine. 



A mixture examined by G. C. Wittstein 4 was composed of 15 parts 

 Prussian blue (or indigo), 35 parts lead chromate, 35 parts clay and 

 gypsum, and 15 parts water. According to Nanning, coffee beans are 

 colored blue by shaking with finely powered iron. 



Indigo and Prussian blue may be detected by the microscope or 

 chemically (see page 881 for methods). Lead chromate should be ex- 



1 Analyst, 9, 128. 



* Bull, cle la Soc. Chim. tie Paris, 47, 7; Chem. News, 56, 24. 



3 Chem. Centrbl., 1887, No. 47; Rep. f. aual. Chem., 1887, 765. 



4 Chem. News, 33, 194. 



