Artificial Stone

ARTIFICIAL STONE.

Many formulas have been proposed for making artificial stone, as the records of the patent office show. Nearly all of the proposed substitutes for natural stone consist of ordinary hydraulic cement, sand, gravel or broken stone, and some ingredient that is claimed to confer some peculiar advantage to the product. In many cases the peculiar ingredient is harmless and useless, in some it is only a coloring matter, and in others it adds a little initial strength; but the most valuable ingredients are only some form of waterproofing (* 369-77).

Few, if any, of the artificial stones have any advantage over ordinary blocks of cement mortar or concrete made waterproof by careful selection of the ingredients and by proper manipulation, or by adding a waterproofing material.

However, there are two forms , of artificial stone, the Ransome and the Sorel, which do not depend upon ordinary hydraulic cement for their strength and hardness, and are therefore of a little interest because of the form of cementing material employed, although they are not of much practical value. The patents on these two have long since expired.

R&w8OME

STONE. This is made by forming in the interstices of sand, gravel, or any pulverized stone, a hard and insoluble cement-. ing substance, by the natural decomposition of two chemical com pounds in solution. Sand and the silicate of soda are mixed in the proportion of a gallon of the latter to a bushel of the former and rammed into moulds, or it may be rolled into slabs for footpaths, etc. At this stage of the process the blocks or slabs may be easily

cut into any desired form. They are then immersed, under pressure, in a hot solution of chloride of calcium, after which they are thor oughly drenched with cold water—for a longer or shorter period, according to their size—to wash out the chloride of sodium formed during the operation. In England grindstones are frequently made by this process.

SoREL

STONE. Some years ago, M. Sorel, a French chemist, discovered that the oxychloride of magnesium possessed hydraulic energy in a remarkable degree. This cement is the basis of the Sorel stone. It is formed by adding a solution of chloride of magnesium, of the proper strength and in the proper proportions, to the oxide of magnesium. The strength of this stone, as well as its hardness, exceeds that of any other artificial stone yet produced, and may, when desirable, be made equal to that of the natural stone which furnishes the powder or sand used in its fabrication. The principal use of this process was in making emery wheels, but it is not used for even that now. It is not suitable for a building stone, since it does not resist the weather well.