As a result of his careful experiments, Bush found that although nicotine was present in all the samples of tobacco tested there was no nicotine whatever found in the smoke, except in the case of cigarettes and in this case only traces were found. The reason of this is given as due to the rapid burning of the cigarette which did not allow sufficient time for the complete decomposition of the nicotine. Pyridine was, however, found in the smoke of all tobacco burned. Pyridine is only one-twentieth as toxic as nicotine. Bush concluded, therefore, that pyridine and not nicotine is the toxic factor in tobacco smoke. The same fact was stated several years ago by Rideal (_Disinfection and Preservation of Food_, London and New York, 1903, p. 254), who says: "Tobacco smoke, contrary to popular belief, does not contain nicotine, which is decomposed by the heat; but pyridine and its homologues and the beneficial effects of tobacco in many cases of asthma must be attributed to this latter." The _Lancet_ investigation (see _Lancet_, Ap. 6, 1912, pp. 944-947) was made because "a recent review of numerous analysis of tobacco which have been published from time to time raises some doubt as to whether the results given correctly represent the actual alkaloidal contents of the tobacco." Moreover, to find the relationship of the true amount of nicotine in any tobacco to that in the smoke produced by the combustion of that tobacco, and any modification caused by the method of smoking. The investigation was conducted under the strictest conditions, the most recent methods of chemical research being employed. The following table (given by the _Lancet_) shows the nicotine contents of various tobacco samples and the percentage of nicotine in the smoke: Description of Tobacco. Per Cent Per Cent Per Cent Nicotine Nicotine Nicotine in Tobacco in Smoke in Smoke (Pipe). (Cigarette). Virginian Cigarettes (Sample 1) 1.40 0.74 0.12 Virginian Cigarettes (Sample 2) 1.60 0.60 0.06 Caporal (French) Tobacco 2.60 2.20 0.95 Turkish Cigarettes 1.38 0.51 Egyptian Cigarettes 1.74 0.21 Pipe Smoking Mixture (1) 2.85 2.20 2.25 Pipe Smoking Mixture (2) 2.81 1.53 Pipe Smoking Mixture (3) 2.04 0.23 Perique Tobacco 5.30 1.27 0.57 Cavendish Tobacco 4.15 3.85 Latakia Tobacco 2.35 1.20 Havana Cigar 0.64 0.20