Chance's Artificial Stone is made by melting the Rowley Rag, a basaltic rock found in Staffordshire, and then casting it into the shapes required for different architectural ornaments.

Greenstone, whinstone, or any similar rock, may be treated in the same way.

The moulds are of sand in iron boxes, and are at a red heat when they receive the melted stone. They should cool slowly, in order to obtain a hard material like the original stone; if allowed to cool too quickly the material becomes brittle and glassy.1

Bust's Vitrified Marble is produced by fusing together a mixture of glass and sand. " The soft pasty mass is taken out of the pot on the end of an iron rod, and placed in a small metal mould of any required shape or design. The large proportion of sand used prevents the mass, when thus suddenly cooled, from acquiring such a high state of tension as to be liable to fly to pieces, which would be the case with glass alone. The material, when cool, is either used in the form in which it is cast, or it is broken up into small pieces by the stroke of a light hammer, to be used in the construction of mosaics for pavements, or other purposes.

" Any colour can be given to the mass when in a semi-fluid state by mixing with it the oxides of iron, chromium, cobalt, or such other colouring materials as are usually employed for fired ware. This vitrified marble has been used for the bosses and coloured portions of the string course which extends round the Home and Colonial Offices, and also at the Albert Memorial in Hyde Park." 2

Other artificial marbles are made, which partake of the character of plasters, and will be noticed in Chapter III (Limes, Cements, Mortar, Concrete, Plasters, And Asphaltes. Limes And Cements).

Artificial Paving Slabs and Paving Stones of many kinds are in the market They are often composed of Portland cement concrete (see p.210),very carefully made, with hard aggregates and the very best cement. It is said that the very finely ground German cement (see p. 164) is used for this purpose. Silicates are sometimes added to give hardness to the mass.