BRUCINE. 
351 
§ 412.] 
crystallised out of dilute hydrochloric or dilute nitric acid in the form 
of yellow or orange-red crystals, very insoluble in water, but dissolving 
readily in dilute acid. On removal by dilution of the product just 
named, neutralisation with ammonia, and addition of a solution of 
chloride of calcium, the oxalate of lime is thrown down. The nitric acid 
test is, therefore, a combined test, consisting of—the production by the 
action of nitric acid (1) of a red colour ; (2) of yellow scales or crystals 
insoluble in water ; (3) of oxalic acid. No alkaloid save brucine is 
known to give this reaction. 
There are other methods of producing the colour test. If a few 
drops of nitric acid are mixed with the substance in a test tube, and 
then sulphuric acid cautiously added, so as to form a layer at the bottom, 
at the junction of the liquids a red zone, passing into yellow, is seen. 
A solution of brucine is also coloured red by chlorine gas, ammonia 
changing the colour into yellow. 
Fliickiger 1 has proposed as a test mercurous nitrate, in aqueous 
solution with a little free nitric acid. On adding this reagent to 
a solution of brucine salt, and gently warming, a fine carmine colour 
is developed. 
Opianic acid 2 is an excellent reagent for the identification of brucine. 3 
If added to a brucine solution of even 1 : 1000, there is an immediate pre¬ 
cipitation of prismatic crystals—occasionally rosettes. Should any of 
the crystals be of fairly perfect form, the angles a and b are approximately 
114°, and the angle at c 132°. The refractive indices are 1-51 and 1*74 ; 
.Aj 
the difference, —0-23, is a negative one ; the extinction is direct. In 
mixtures of strychnine and brucine, the latter alkaloid may be detected 
by taking advantage of the greater solubility of brucine in water; 
brucine dissolves in 320, strychnine in 6000 parts of water. A film of 
strychnine and brucine is treated with a few drops of cold water, and the 
test applied to the cold water extract, concentrated if necessary. On 
the other hand, to detect a small amount of strychnine with much 
brucine, it is best to resort to sublimation. Strychnine (p. 263) sublimes 
1 Archiv f. Pharm. [3], vi. 404. 
2 Opianic acid is not at the present time in English commerce. It can be made 
by adding gradually and quickly to a boiling solution of 2 parts of narcotine in 30 of 
water and 3 of sulphuric acid, 3 parts of manganese dioxide at 00 per cent. After 
cooling and standing some hours opianic acid crystallises out.—Beckett and Wright, 
J. Chem. Soc., T., 1875. 
3 A. Gruttorink, “ Beitriige zur mikrochemischen Untcrsuchung cinigcr Alkaloid,” 
Zcil. f. anal. Chemie, 1012. 
