Action of Tobacco Smoke 337 



combustion of the tobaccos through saline solution by means of a suction 

 pump, 1 gram of each variety of tobacco being used with 100 c.c. of saline. 

 The stroke of the pump was so arranged that the smoke was drawn through 

 the saline about twelve times a minute. The procedures with the two 

 tobaccos were conducted under identical conditions, and so arranged that 

 the combustion of the two tobaccos was effected in equal times. The 

 relative amounts of nicotine w6re determined as before, by coTnparing the 

 rise in blood -pressure produced when the solutions were injected into a 

 pithed cat. The results showed that when the smoke solution from the 

 Manilla tobacco caused a rise of 2 mm. Hg, the smoke solution from the 

 cigarette tobacco caused a rise of 1 mm. Hg. 



From these experiments the remarkable fact comes out that, whilst the 

 Virginian tobacco contains a much greater percentage of nicotine than 

 the Manilla, yet, after combustion, the smoke from the Manilla contains 

 considerably the larger percentage. This circumstance is explained as 

 follows : — During the slow combustion of a cigar, as in ordinary smoking, 

 immediately behind the point of combustion is an area in which the water 

 and other volatile substances in the tobacco condense ; during the act of 

 smoking the greater portion of the nicotine at the seat of combustion is 

 destroyed (50 per cent.), and the nicotine which finds its way into the mouth 

 of the smoker is probably derived from the hot gases passing through the 

 moist area and volatilising certain of the more volatile principles of the 

 tobacco, of which nicotine is certainly one. So that the smaller the moist 

 area behind the point of combustion, the less likely is the smoke to contain 

 volatile toxic bodies. It will be immediately suggested that a thin cigai- 

 or a cigarette will yield fewer of these products than a thick cigar, for the 

 thin cigar or cigarette obviously permits a relatively greater evaporation to 

 take place. Moreover, if a thick cigar be unrolled and made up in a thinner 

 body, the percentage of nicotine destroyed during combustion is increased. 

 The experience of many smokers also agrees with this hypothesis, for there 

 are those who will always avoid a thick cigar because, whatever be the 

 strength of the leaf from which it is made, unpleasant symptoms are 

 invariably experienced. 



III. The Relative Action of the Constituents of Tobacco S\iOkE. 



It has been pointed out already that the important constituents of 

 tobacco smoke are nicotine and certain pyridine bases, including especially 

 pyridine itself and collidine. The following experiments were conducted 

 with a view to determine the relative effects of these alkaloids. 



i. Plain Muscle. — The action on plain muscle was determined first by 

 means of " ring " preparations of the frog's stomach. These were suspended 

 in Ringer's solution and arranged to record on a slowly moving drum by 

 means of suitably weighted levers. 



