Abstract :
The paper deals primarily with the effect which atmospheric exposure has upon the electrical conductivity of certain light aluminium alloys, the period of exposure extending to 24 years. Twenty-five alloys of aluminium with the metals copper, nickel, manganese and zinc in amounts not exceeding 1 or 2 per cent have been tested at intervals for electrical resistance, whence the variation in conductivity has been found. In the case of copper alone, or copper and manganese jointly, the conductivity continuously diminishes in value, whereas with copper and nickel, or copper and zinc, or combinations of all three of these, the conductivity at first decreases, and then in some cases increases in a remarkable manner, finally attaining a more or less constant value. The factors concerned are the specific resistance of the alloy and the loss of metal due to corrosion, and it has been found possible to separate the total variation into these two classes. Some further work deals with the exposure of copper conductors.
