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Damp-proof casings and methods of providing against damp are matters which concern the structural engineer, if only in some stages of his task, and Messrs. F. T. Carson and F. V. Worthington, in the July issue of the “Bureau of Standards Journal of Research" have furnished much valuable data, which might well be used in the formulation of a standard specification. The work was carried out at the request of the National Lumber Manufacturers’ Association and 36 samples of building papers, consisting of asphalte-saturated, paraffin-saturated, laminated and asphslte treated and machine finished papers, were tested for weight, thickness, tensile-breaking strength, bursting strength, tearing resistance, water resistance and air-permeability.
The Department of Scientific and Industrial Research has just issued, through H.M. Stationery Office, a volume of its special reports on the mineral resources of Great Britain. It deals with the geological relations, nature and uses, and mineral, chemical and physical properties of ball clays, that is to say, of those plastic "transported" clays which, when fired in an oxidising atmosphere to the temperature of certain pottery ovens approximately 1,150 deg.-1,200 deg. C.-have a white or nearly white colour. They are formed by the decomposition of felspathic rocks, by natural agencies. In this decomposition, silicates such as the felspars break down, and the products ultimately undergo hydration with the formation of the hydrated silicate of aluminium, kaolinite, and, in many cases, mixtures of hydrated oxides. Where these products are found resting in the parent rock, the clays are termed residual; where they have been transported and deposited elsewhere, they are known as transported clays. The china clays of Cornwall are typical examples of the former; the ball clays discussed in this memoir are characteristic examples of the latter. Dr. Alex Scott
Sir Courtauld Thomson, chairman of the Limmer and Trinidad Lake Asphalt Company, in his speech at the annual general meeting in March, referred to the attention the company’s staff was paying to the problem of vibration, and the writers, who have worked in collaboration with the company’s staff, are now able to reproduce some results of experiments recently carried out. W.P. Digby and R.B. Fairthorne