16 | MISCZLLANEOUS PAPERS. 
during the intervals between “ puffs.” The relative amount of nico- 
tine which is to be found in the smoke depends chiefly on the relative 
length of the unsmoked portion of the cigar and on the rate at which 
the smoke is drawn through the cigar. eas 
The point of chief interest, however, is the effect of the citric acid 
on the nicotine content of the smoke. It 1s apparent that in every 
case the quantity of nicotine in the smoke is reduced, while that 
which collects in the residual end of the cigar is correspondingly 
increased. This difference, nevertheless, is too small to account for 
the marked effect produced on the quality of the smoke. Apparently 
the only possible explanation of this pronounced effect on the sharp- 
ness of the smoke is that in the presence of the citric acid the nico- 
tine enters the smoke in the form of a salt rather than in the free 
state, and thereby loses its pungency while still exerting the usual 
physiological effect. 
CONCLUSIONS. 
Tt has been shown in the preceding pages that there is no direct 
relation between the so-called “strength” of tobacco when used 
for smoking purposes and the total content of nicotine. However, 
a distinction must be drawn between two forms of nicotine con- 
tained in tobacco, one of which is easily volatile and readily soluble 
in petroleum ether while the other is volatile only at elevated tem- 
peratures and is almost insoluble in petroleum ether. The unde- 
sirable sharpness or pungency contained in the smoke from certain 
types of cigar-filler tobacco and which constitutes one of the two 
factors included in the term “ strength” as applied to the smoke 
is due almost entirely to the volatile, easily soluble form of nicotine 
which acts as if it were in the free state. On the other hand, the 
true physiological effects of the smoke, as embodied in the term “ full- 
ness,” are proportional to the total quantity of nicotine. 
The pungent, harsh quality of the smoke is partially, but not en- 
tirely, removed by protracted resweating and aging of the tobacco, 
whereby the easily volatile nicotine is largely expelled. This unde- 
sirable property is entirely removed by extracting the tobacco with 
petroleum ether, which simply dissolves out the volatile nicotine. 
Finally, the addition of sufficient citric acid-to the tobacco to com- 
bine with all of this easily volatile nicotine efficiently overcomes the 
sharpness or pungency of the smoke. It can best be added by spray- 
ing the tobacco with an aqueous solution when the fermenting bulks 
are being turned. The addition of the citric acid reduces somewhat 
the amount of nicotine in the smoke of the cigar, but not enough 
to account for the marked effect on the quality of the smoke. It 
is suggested, therefore, that probably the nicotine enters the smoke 
in the form of a salt rather than in the free state, thereby losing its 
pungency. 
141—1 
