ON NICOTINE. 
145 
precipitate with solution of nicotine, as chloride of platinum would 
do ; with an excess of nicotine it acquires a straw color, and it is 
decolorized by the action of heat. Ammonia, on the contrary, 
immediately decolorizes the aqueous solution of iodine without 
rendering it turbid. Pure tannic acid gives with nicotine an 
abundant white precipitate. Ammonia gives no precipitate, but 
imparts a red color. 
It is interesting to compare the physical and chemical proper- 
ties of nicotine with those of conicine. 
Conicine is yellow ; its smell resembles that of the urine of the 
mouse, and differs entirely from that of nicotine ; it strongly blues 
reddened litmus paper. Added to water and shaken with it, 
it floats on the surface and is not readily dissolved. Ether 
dissolves it easily. When heated in a capsule it forms 
white vapors, having a strong smell of celery mixed ivith 
that of the urine of the mouse. "Weak tincture of iodine 
yields a white precipitate, which acquires an olive color 
with excess of the tincture. Pure and concentrated sulphuric 
acid does not alter it; when the mixture is heated it acquires a 
greenish brown color, and if the heat be continued it becomes 
blood-red and afterwards black. Nitric acid imparts to it a topaz 
color, which is not changed by the action of heat. Hydrochloric 
acid yields white vapors as ammonia does, and renders it violet, 
especially when heated. Tannic acid gives a white precipitate, 
and chloride of platinum a yellow precipitate. The red per- 
manganate of potash is immediately decolorized. Corrosive sub- 
limate yields a white precipitate. Acetate of copper gives a 
gelatinous blue precipitate, less soluble in an excess of conicine 
than is that formed with nicotine. Chloride of cobalt behaves 
with it as it does with nicotine. Chloride of gold gives a lights 
yellow precipitate. Neutral acetate of lead does not give any pre. 
cipitate ; neither does the subacetate. Chloride of zinc gives a 
white gelatinous precipitate soluble in excess of the conicine. 
Sulphate of sesquioxide of iron gives a yellow precipitate. The 
words in italics indicate the means of distinguishing conicine from 
nicotine — London Pharm. Journ, 
13 
