142. COLOUR-REACTIONS. 



121 



per cent. These figures are true for fresh oils only, and for tem- 

 peratures ranging from 20 to 22. l 



I found the following proportions of weaker alcohol necessary 

 to form clear mixtures with the foregoing oils : 



142. Colour-reactions. I have observed the following colour- 

 reactions with certain ethereal oils : 2 

 Solution of bromine in chloroform (1 in 20), in the proportion of 



10 to 15 drops to one of oil, gives colourless mixtures with oils of 

 turpentine, caraway, lemon, coriander and cardamoms ; yellow 

 with bergamot, bitter orange and neroli ; slowly turning green with 

 cloves, ginger, lavender, cajeput, cascarilla ; slowly turning greenish- 



11 ne with ol. menth. crisp., oils of juniper, pepper and galangal ; 

 greenish-brown or brown with sweet marjoram, dill, cummin and 

 valerian ; a more or less fine rose, red, or reddish-violet tint is 

 gradually produced by rosemary, fennel, anise, star-anise, cinna- 

 mon, nutmeg, thyme, peppermint, myrrh and parsley ; broivnish- 

 violet with mace; blue or bluish-violet with cubebs, copaiba, 

 amomum, laurel, sandal- wood and sweet flag ; orange with oil of 

 worm-seed, oil of cedar-wood ; and with camphor. 



J X. Repert. f. Pharm. xxii. 1, 1872 ; Pharm. Journ. and Trans. [3], vi. 

 541 d seq. See also Godeffroy und Ledermann, Zeitschr. d. allgem. oesterr. 

 Apotheker Ver. xv. 381 et <?*/. ; Jahresb. f. Pharm. 394, 1877. 



- Pharm. Journ. and Trans. [3], vi. 681 ; Archiv d. Pharm. [3], xii. 289. 

 See also Hager, Pharm. Centralblatt, 137, 169, 195, 1870 ; and Fliickiger, 

 Schweiz. Wochenschr. f. Pharm. 261, 1870. 



