by machinery to shake down the mixture and to get rid of air holes.  While it is still wet the casting is taken out of the mould, its edges are cleaned, and after the lapse of one day it is placed in a bath, of silicate of soda.  Should the casting be allowed to get dry before it is placed in this bath, no good results would be obtained; it is left in the bath for seven days.  When delicate stone carvings have to be copied, the moulds are of a compound of gelatine, from the flexible nature of which material designs much undercut can be reproduced.  For the foregoing particulars we are indebted to Mr. William Millar, the working manager at West Kensington.  Sometimes the composition is cast in large, heavy slabs, moulded on the top to resemble the surface of roads of granite blocks.  A feature of the invention is the rapidity with which the composition sets.  For instance, the manager states that a roadway was finished at the Inventions Exhibition at seven o’clock one night, and at six o’clock next morning four or five tons of paper in vans passed over it into the building, without doing any harm to the new road.  In laying down roads, much of the preparation of the material is done on the spot, and the composition after being put down unsilicated in a large layer has the required design stamped upon its wet surface by means of wooden or gutta-percha moulds.  As regards the durability of the composition, Mr. T. Grover, one of the directors, says that the company guarantees its paving work for ten years, and that the paving, the whole of the ornamental tracings, and some of the other work at Upton Church, Forest Gate, Essex, were executed by means of Wilkes’ metallic cement three years ago, and will now bear examination as to its resistance to the action of weather.  Some of this paving has been down in Oxford Street, London, for more than six years.  Mr. A.R.  Robinson, C.E., London agent of the company, states that the North Metropolitan Tramway Company has about 25,000 yards of it in use at the present time, and that the paving is largely used by the War Office for cavalry stables.  The latter is a good test, for paving for stables must be non-slippery and have good power of resisting chemical action.

In the Wm. Millar and Christian Fair Nichols patent for “Improvements in the means of accelerating the setting and hardening of cements,” they take advantage of the hydraulicity of certain of the salts of magnesia, by which the cements set hard and quickly while wet.  For accelerating the setting of cements they use carbonate of soda, alum, and carbonate of ammonia; for indurating or increasing the hardening properties of cements they use chloride of calcium, oxide of magnesia, and chloride of magnesia or bittern water; for obtaining an intense hardness they use oxychloride of magnesia.  The inventors do not bind themselves to any fixed proportions, but give the following as the best within their knowledge.  For colored concretes for casts or other purposes they use Carbonate