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The influence of air permeability of cigarette paper on the yield of condensate and on its composition was examined. Total particulate matter and nicotine in the smoke decrease with increasing permeability of the paper. The decrease results from the smaller quantity of tobacco burnt in the mainstream. Higher combustion cannot be obtained by paper of greater permeability. The content of condensate of 3,4-benzopyrene is constant. Total particulate matter and nicotine in the smoke - measured in per cent of the tobacco smoked in the mainstream - are also constant.

The present paper shows the detectable factors on which a sorption isotherm depends. Even if it is well-known that a sorption isotherm is most essentially conditioned by influences of the respective tobacco variety, other factors, such as temperature, initial moisture content, or fibre dimension, play a part as well. In general, a sorption isotherm constitutes a ''summation'' of such factors and, in the end, a combination of desorption and adsorption if the tobacco is dried or moistened from the average commercial moisture content. The tobacco hysteresis is experimentally investigated and discussed

In two papers, Hoffmann and Wynder have described an analytical method for the quantitative determination of some phenols in the smoke of cigarettes. An application on cigarette filters permitted the statement that these filters may selectively retain phenols from the smoke. It is shown here that the analytical method has a limited precision and accuracy, sufficient to ascertain the effect of selectivity, but insufficient to detect relatively small differences between filters of similar retention capacity. It is shown that the interpretation of the results given by Hoffmann and Wynder is facilitated through the introduction of the notion of ''relative phenol retention'', i. e. the quotient of the ''phenol retention" to the ''T. P. M. retention'', whereas the ''selective phenol reduction". i. e. the arithmetic difference between these two criterions, is inapt to express the capacity of specific selectivity of a given filter, especially if the pressure drop of this latter is unknown. When classifying the filters studied by Hoffmann and Wynder according to their "relative phenol retention'', one arrives at different conclusions than these authors.