LONDON. Faraday Society, December 12, 1917.—Mr. W. R. Bousfield, vice-president, in the chair.—Prof. A. W. Porter: The thermal properties of sulphuric acid and oleum. The object of this paper is to supply data at various temperatures for the heats of solution and dilution and evaporation, both of sulphuric acid and oleum. Pre-existing data apply only to atmospheric temperatures; but technical processes take place at various temperatures up to 200° C. or above. These additional data are obtained by indirect methods either from vapour pressures (of H2O or SO3) by means of Clapeyron's formula or from thermal capacities.—W. R. Bousfield: Isopiestic solutions. Solutions of KC1, LiCl, NaCl, and KNO3 of equal vapour pressure are placed together in an exhausted vessel, so that interchange of aqueous vapour may take place. Hence is indicated an accurate method of determining the vapour pressure of an aqueous solution, by comparison with the equal vapour pressure of a solution of LiCl. The observations lead to the conclusion that for a pure salt without water of crystallisation there is, at a given temperature, a certain vapour pressure of water below which the dry salt surrounded bv aqueous vapour will not take up water, and will, if it is not dry, become dried. This pressure may be called the critical hydratidn pressure of the salt at the given temperature.—Dr. J, W. McBain: Notes on the system of recording rate of chemical reaction. The usual equation representing rate of reaction may be written in the form fci = (remainder of expression). The author proposes so to choose the unit of time that fe is always unity. A single number will then completely record the rate of reaction.—A. L. Feild: The viscosity of blastfurnace slag and its relation to iron metallurgy (seep. 373). O.G. Le Bas: The refractivities of saturated and un-saturated compounds. The refractivities of unsaturated compounds, together with unsaturated systems containing conjugated unsaturated groups, have been considered. Benzene has been shown to be possessed of no anomaly. Cross-linking has been assumed in some cases. The effects of conjugation of ethenoid and carbonyl groups have been shown, whilst nitrates, nitrites, and nitro-compounds have been studied. The oximino-group especially has been taken into consideration. The cycle-paraffins, substituted and un-substituted, have been considered, together with a number of terpenes and derivatives. Anomalies have been connected with the side-chains or substituents and the appropriate numbers ascertained. The larger anomalies are connected with the trimethylene ring. Those for benzene derivatives have been ascertained. The unsubstituted hydrocarbons show no anomalies.—Dr. E. B. Ludlam: The effect of hydrogen chloride on the nitrogen-hydrogen equilibrium. The paper records an experimental attempt tft simplify the difficult conditions of high temperature at high pressure under which the Haber synthesis takes place. It was thought that the presence of hydrochloric acid during the synthesis would displace the equilibrium in the direction of the formation of ammonia. The result of the experiments was negative.—Dr. H. B. Maxted: The influence of carbon monoxide on the velocity of catalytic hydro-genation. The inhibitive effect of small percentages of carbon monoxide on the velocity of hydrogenation of olive oil in presence of nickel has been studied quantitatively.