Victoria Stone consists of washed, finely-powdered granite, bound together with the strongest Portland cement, and then hardened by immersion in silicate of soda.

The silicate is formed by boiling ground Farnham stone in cream caustic soda.

A mixture of four parts of crushed granite with one of Portland cement is allowed to set for three days or more into a hard block moulded to the required shape. It is then immersed in the silicate of soda for some seven or eight weeks.

The lime in the cement combines with the silicate, the whole mass being indurated by the silicate of lime thus formed.

Characteristics And Uses

This artificial stone is used chiefly for paving, which is said to be more durable, to be cheaper, and to stand a greater crashing force, than Yorkshire flags. It is used also for window sills, coping stones, caps for piers, stairs, landings, troughs, tanks, sinks, etc.

It weighs from 140 to 160 lbs. per cubic foot, and absorbs from 2 to 6 per cent of its weight of water in 24 hours. The thinner flags are less compact and more absorptive than the thicker ones.2

" The white colour, semi-transparency, and extreme hardness of this oxy-chloride, as well as the small quantity which is required for binding together a considerable mass of any material, facilitate the production of imitations of any description of stone, and render it highly probable that it will play an important part in the future history of artificial stone." 1

Where Used

This stone has been used for the whole of the external stonework, except the cornice, at Fresh Wharf, London Bridge.

Also for the panels in the tower, and for the chimney shafts at Messrs. Peek and Frean's biscuit manufactory at Bermondsey, and for paving in many parts of London.

Silicated. Stone is made in the same way as Victoria stone, and is used for paving slabs and drain pipes.

Sorel Stone is so called after M. Sorel, a French chemist.

1 Dent.

2 Wray.

Native carbonate of magnesia, or magnesite, is calcined and mixed with sand or powdered marble. It is then wetted with waste liquor from salt works containing a large proportion of magnesium chloride, pugged, and then rammed or stamped into iron, wooden, or plaster moulds.

It hardens rapidly, setting throughout its mass like ordinary hydraulic cement. In 24 hours it is hard enough to remove from the moulds, and the blocks will bear handling in three or four days.

The proportion of magnesia to the inert material bound together varies from 3 to 15 per cent.

This stone has been found to resist an enormous compression. The resistance of 2-inch cubes varied in different experiments from 4923 to 21,562 lbs. per square inch.