8 MISCELLANEOUS PAPERS. 
in other respects the smoke possesses the peculiar pungency or harsh- 
ness just mentioned. This defect is partially and sometimes efficiently 
remedied by resweating, followed by a long aging process. In some 
cases this resort fails and it is necessary to blend the tobacco with some 
very mild type before it can be used to advantage in the manufacture 
of cigars. This sharp, biting quality has often been attributed to the 
presence of an ethereal oil, but such a substance has never been isolated 
from cured tobacco. 
In the course of our experiments with a sample of domestic filler 
tobacco possessing the above-mentioned objectionable character to a 
marked degree, it was found that this quality was entirely lost after 
the tobacco had been extracted with petroleum ether. After evap- 
orating off the petroleum ether from the extract the residue upon 
warming gave off fumes which were extremely pungent and irrita- 
ting to the nose and throat. Upon examination these fumes were 
found to consist essentially of nicotine vapors. The nicotine is 
readily isolated from the extract by agitating the solution in petro- 
leum ether with water containing sulphuric acid. The aqueous layer 
containing the nicotine is well washed with petroleum ether and 
after adding an excess of alkali to free the nicotine from the sulphuric 
acid is once more extracted with petroleum ether of very low boiling 
point or with ordinary ethyl ether. After evaporation of the ether 
from this extract the nicotine is left as a residue in almost pure 
condition. This residue retains all the pungency of the original ex- 
tract, while the latter after removal of the nicotine no longer pos- 
sesses this property. 
A large sample of nicotine was purified by converting it into the 
citrate in aqueous solution and repeatedly extracting this solution 
with ether. The nicotine was then liberated with an excess of alkali, 
extracted from the aqueous layer with ether, and the ether solution 
dried. After evaporating the ether the nicotine was twice distilled 
in a current of hydrogen. The odor of this product was identical 
with that obtained by extracting the tobacco with petroleum ether, 
as already described. Although the peculiar sharpness or pungency 
of the smoke from tobacco of the kind in question is removed by ex- 
tracting the tobacco with petroleum ether, and this quality is due to 
nicotine, all of the nicotine is not by any means removed in this treat- 
ment. 
Kisshng has studied the relative amounts of nicotine salts removed 
from samples of tobacco from several different sources by extraction 
with petroleum ether, with ordinary ether, and with alcohol. A cer- 
tain definite portion of the nicotine, usually much less than half, is 
readily removed by extraction with petroleum ether, while further 
treatment with this solvent removes only traces of the remaining 
nicotine. It is perfectly clear, then, that nicotine is present in 
£41-—1 
et FOI 
