A New Kind of Building Material.
The new kind of building material, some time since announced as a proposed substitute for ordinary stone or brick, is now receiving special endorsement on account of its freedom, under various and repeated tests, from the usual liability to crack or fracture. To insure this property, with the other essential adaptations, silicic acid is used, powdered and cleansed from all impurities ; five to ten per cent of this is mixed in warm river or rain water and this is applied to slaked or well burnt lime, or added to hydraulic lime, the resulting product being mixed with sand and small portions of fluorspar. This mixture is cast into molds, in various shapes as may be desired and, after removal, the castings are left to dry from twelve to twenty-four hours, which brings them to a condition as dry as atmospheric air; in this state they are brought into a steam boiler and steam blown through so as to drive out all air, after which the boiler is hermetically sealed up and steam let in under a pressure of ten atmospheres. In this high pressure steam bath the stones remain for forty-eight to seventy-two hours, afterward being submitted to a bath of boiling and saturated chloride of calcium for six to twelve hours, also under a pressure of about ten atmospheres, in the same boiler, and the condensed water may be used for the bath. The stones are allowed to dry in the open air or. more quickly, by circulating steam inside the boiler after the chloride of calcium has been withdrawn and prior to taking out the stones. __