In this paper Mr Peddie described some preliminary experiments made on the resistance of dilute solutions of sulphuric acid (ordinary commercial). The solution is enclosed in a glass tube, which passes through a metal vessel containing water. Each end of the tube dips into a separate vessel containing some of the acid solution, and a platinum electrode is placed in each vessel. This apparatus is joined in circuit with a Helmholtz tangent galvanometer and a Brush dynamo. The current from the dynamo is then passed through the arrangement, and the water surrounding the tube is stirred constantly until its temperature ceases to rise. The temperature of the water, the temperature of the air, and the current strength are then noted, and the resistance is obtained by the application of Joule's Law, the rate of loss of heat being known.