§ 142. COLOUR-BE ACTIONS. 



121 



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

 peratures ranging from 20^ to 22°. ^ 



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 :- 



Sohiiion of hromine 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 ; slouii/ turning green with 

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

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

 greenish-hromi or hrown 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 ; hrowiiish- 

 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. 



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

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

 Apotheker Ver. xv. 381 et seq. ; 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 Plückige.-, 

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



