Of the following papers those marked * were read :-"20. "Studies on the formation of ozone. 11." By W. A. Shenstone and Martin Priest. The authors have submitted a known volume of oxygen confined in an ozone generator of the Brodie pattern to the influence of discharges produced by varying differences of potential, and hsve determined the amount of ozone produced by observing the change in volume by means of a mercury manometer. A full description is given of the contact breaker used, of the

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... ns adopted to measure the differences of potential, to prevent the ozone coming into contact with the mercury, &c. in some of the experiments the discharge from an induction coil, in others that from an influence machine, mas used. The following conclusions are drawn :-1. It is possible to obtain very fairly concordant results. 2. Provided that the path of the discharge be not too short, at any