144 
ON NICOTINE. 
blackens and disengages sulphurous acid. With cold hydrochloric 
acid it disengages white vapors as ammonia does ; if the mixture 
be heated it acquires a violet- color, the intensity of which in- 
creases with prolonged ebullition. Nitric acid, aided with a 
little heat, imparts to it an orange-yellow color, and white vapors 
of nitric acid are first given off, then red vapors of hyponitrous 
acid. If it be further heated the liquor becomes yellow, and by 
ebullition it acquires a red color resembling that of chloride of 
platinum. Prolonged ebullition gives a black mass. Heated 
with stearic acid it dissolves and forms a soap, which congeals on 
cooling, and is slightly soluble in water, and very soluble in 
heated ether. The simple salts of nicotine are deliquescent, and 
difficultly crystallizable. The double salts which it yields with 
the different metallic oxides crystallize better. 
The aqueous solution of nicotine is colorless, transparent, and 
strongly alkaline. It acts like ammonia on several reagents; 
thus, it gives a white precipitate with bichloride of mercury, 
acetate of lead, protochloride and bichloride of tin ; a canary 
yellow precipitate with chloride of platinum, which precipitate is 
soluble in water ; a white precipitate with salts of zinc, which is 
soluble in excess of nicotine ; a blue precipitate with acetate of 
copper. This precipitate is gelatinous, and soluble in excess of 
nicotine, forming a blue double acetate, similar to that formed by 
ammonia with the same salt. It gives an ochre-yellow precipi- 
tate with salts of the sesquioxide of iron, insoluble in excess of 
nicotine. With sulphate of protoxide of maganese it gives a white 
precipitate of oxide, which speedily becomes brown by contact 
with the oxygen of the air. It separates the graen sesquioxide 
from the salts of chromium. The red permanganate of potash is 
instantly decolorized by nicotine, as by ammonia, although this 
latter alkali acts more slowly and must be used in larger propor- 
tion. 
The following reactions may serve to distinguish the aqueous 
solutions of nicotine from ammonia. Chloride of gold yields a 
reddish yellow precipitate, very soluble in an excess of nicotine. 
Chloride of cobalt yields a blue precipitate, which changes to 
green ; the oxide thus formed does not readily dissolve in excess 
of nicotine, whilst ammonia dissolves the green precipitate and 
forms a red solution. Aqueous solution of iodine gives a yellow 
