An account of further experiments tried at Chatham, for the purpose of obtaining an artificial water cement

Abstract

Colonel Pasley’s paper was resumed and concluded. The present paper is occupied with the detail of the experiments made by the author in the prosecution of the object of his former inquiry, already submitted to the Royal Society, into the best means of obtaining an artificial Water Cement. These experiments were tried on a larger scale than the former, and were applied more especially to the practical purposes of building. He recommends that the cement should not be applied in two coats, the surfaces being less likely to adhere when this is done, than if the whole cement is applied at once. He succeeded in various ways, in forming cements which appeared to be the same, in all their properties, with natural cements: and he has now employed them in buildings on a scale sufficiently extensive, and in situations sufficiently exposed to the weather, to be brought to the test of experience in the course of time. Some experiments were also made by the author, with the view of forming an artificial lithographic stone, by a calcined mixture of chalk and carbonate of magnesia: but their density could not be rendered such as to answer the purpose intended. On the whole he draws the general conclusion, that in all attempts to imitate the water cements of nature by artificial means, carbonate of lime must be the essential ingredient; next to which in point of importance are silica and alumina. The author succeeded in forming a very good cement by uniting these three ingredients. By the addition of a small proportion either of the protoxide of iron or of the oxides of lead, or of manganese, the qualities of the compound were very much improved ; these latter ingredients appearing to produce a more intimate union of all of them, and a more speedy and permanent induration of the mass.