degrees of association (Part 11), are indicated in the Table by an asterisk. For such compounds, the plots of log T against log Tbenaene, both temperatures corresponding to the same vapour pressure, are expected to be linear (Part 111). The tabulated B values are then those derived by solution of eqn. 13 of Part 111, and the mean deviations between the experimental temperatures for the range 10-760 mm. and those calculated from this

value, 4.4 kcal, agrees well with the values obtained, e.g., by infrared spectroscopy (5).

The action of methyl alcohol on pyridine in the vapour phase in contact with alumina or aluminium silicates gives methylpyridines, including the commercially valuable β‐picoline. The separation of this base from the other homologues of similar boiling‐point can be effected by taking advantage of the fact that it does not condense with m‐nitrobenzaldehyde to form a stilbazole. Small yields only of β‐picoline are obtained by heating (a) ammonia and (b) urea with glycerol in the presence of the same catalysts.

The physical properties of eleven alkanediols and two dihydric phenols have been determined, and their degrees of association estimated by an empirical relationship. The dependence on molecular structure of the apparent extent of association so deduced has been investigated, and the nature of the association complexes in the pure liquid state examined.FOR non-associated liquids, it has been shown that the of molecular size, shape, and polarity, the average value variation of liquid viscosity (q) with vapour pressure (p) being 0.220. It is readily shown that a = Evisc./E, is given by the semi-empirical relationship: log = where EviS-is the " energy of activation of viscous flow '' ba logp, where ZJ is the specific volume, and b and Q [Le., R d log, qdv/d(l/T)], and E is the energy of vaporisof a very few possessing molecules of highly spherical 1963, 1986, 1995. shape, a is not only independent of temperature but also are constants. For all such liquids, with the exception *

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