NATURAL DYES AND COLORING MATTERS. 445 



The dye is not commonly used by the Filipinos, probably for the reason 

 that it does not directly dye cotton. Cotton mordanted with tannin is 

 colored a dark red. In India the myrobalans, which are used in one stage 

 of the process, furnish the necessary tannin. The dye was formerly 

 widely used in Java and India as a fast red for calico, but its cultivation 

 has greatly decreased. 



TANNIN". 



The barks of several species of trees said to be used in dyeing blacks 

 or blues were examined and the value of nearly all of these specimens 

 was found to be due to the tannin contained in them. Thus Terminalia 

 nitens Presl, Terminalia catappa L., Pterospermum niveum Vicl., 

 Pygeum preslii Merr., Macaranga tanarius Muell.-Arg., Ceriops tagal 

 C. B. Eob., Acacia rv.gata Ham., Xylocarpus obovatus Juss., and Ehretia 

 buxifolia Eoxb., contain a greater or less quantity of tannin, but their 

 tinctorial power in most cases is very slight. Soaking in mud is a com- 

 mon practice when the natives desire to dye black with these barks. This 

 doubtless finds its explanation in the formation of black iron-tannin com- 

 pounds. By virtue of the tannin contained in them, these barks are of 

 some value when used as mordants for other dyes. The bark of Oro- 

 xylum indicum Vent, is said to be used as mordant, but the specimen 

 examined contained only traces of tannin. 



Betel nuts or the fruits of the areca palm, Areca catechu L., are the 

 source of a variety of catechu, known as Bengal catechu; they are used 

 by the Filipinos to produce red and black shades. According to 

 Ishikama 26 the nuts contain about 18 per cent of tannin, which explains 

 their employment in dyeing to black shades. 



THE BLACK COLORING MATTER OE EBONY. 



Several species of the Ebenacece are used by the Filipinos to give black 

 shades; these are entirely different in character from the tannin-iron 

 colors. It has been suggested that the black coloring matter in the dense, 

 black heartwood of certain of the Ebenacece, commercial ebony, is prob- 

 ably an insoluble iron-tannin compound. Any uncertainty on this 

 point is removed by the fact that the ash of the black heartwood is white 

 and contains only the smallest traces of iron. Baspings of the black 

 wood and the white wood growing next to it were extracted with hot 

 water and with a 1 per cent alcoholic solution of caustic soda, but no trace 

 of tannin could be detected in the extracts. 



Molish 2T ascribed the black coloring matter of ebony wood to changes in the 

 resinous secretion by a process of humification with the formation of humus 

 acids. 



""Chem. News (1880), 42, 274. 



27 Sitzungsler. AJcad. Wiss. math.-nat. Klasse Wien. (1879), 80, I, 66. 



