NATURAL DYES AND COLORING MATTERS. 449 



stated that santalin has the formula Oh-EL^Oi (OCH 3 ). Franchimont states that 

 he obtained resorcinol by fusing the dye with causic potash and that zinc dust 

 and a solution of caustic potash or zinc and hydrochloric acid do not reduce the 

 dye to a colorless base. By oxidation with alkaline permanganate he obtained 

 a mixture having a strong odor of vanillin, but he was unable to isolate that 

 body in quantities sufficient for identification. 



A comparison of santalin with the red coloring matter of narra was 

 made by me. A small hand specimen of Pterocarpus santalinus L. f., 

 kindly furnished by the conservator of forests, Central Circle, Madras, 

 India, was ground and extracted in the same way as narra. Both woods 

 contain the two colorless crystalline compounds, pteroearpin and homop- 

 terocarpin and both contain a yellow coloring matter which shows a 

 greenish-blue fluorescence on the addition of alkalies. However, the 

 two red colors are not identical. Santalin melted at 104° as described 

 above, but the coloring matter from narra, which may be called narrin 

 for want of a better name, does not melt, but swells with charring at 

 about 180°. I have found that both dyes are decolorized by zinc dust 

 in caustic potash solution, or by sodium amalgam in dilute alcohol, the 

 color reappearing when they are oxidized by the air. The reduction 

 product of narrin is an amorphous, light yellow substance which rapidly 

 becomes brown on oxidation by the air. Both santalin and narrin are 

 precipitated from their alcoholic solutions by alcoholic potassium ace- 

 tate, forming potassium salts according to the general reaction discovered 

 by A. C. Perkin. 41 



The copper salts of santalin and narrin were prepared by this method, 

 using an alcoholic solution of copper acetate. On ignition these copper 

 salts gave the following results. 



Santalin. 



I. 0.2162 grams of the copper salt gave 0.0293 grams CuO. 

 II. 0.2100 grams of the copper salt gave 0.0269 grams CuO. 



I. Cu 

 II. Cu 



= 



Found 



(per cent). 



10.43 

 10.21 



Calculated (per 



cent) for 



(C 15 Hi 3 5 ) 2 Cu. 



10.34 



Narrin. 



I. 0.2097 grams of the copper salt gave 0.0165 grams CuO. 

 II. 0.2176 grams of the copper salt gave 0.0170 grams CuO. 



Found 

 (per cent). 



I. Cu 6.26 



II. Cu 6.22 



The difference in the percentage of copper in the two salts is very 

 marked. 



a Journ. Chem. Soc. London (1899), 75, 433; ibid. (1903), 22, 129. 



