Ransonits Artificial Stone 



429 



manufacture of the patent stone is conducted 

 much does not need to be said. It is plain, 

 substantial, and of large extent. The works 

 are near the Thames, with which they have 

 communication by a jetty and a tramway. 

 At the time of our visit a large barge, laden 

 with very fine sand, to be converted anon 

 into solid stone, was delivering cargo at the 

 jetty; the sand being wheeled to the works, 

 where it is sifted, thoroughly dried, and then 

 shot into cells ready for use. Passing into the 

 main building, we find that above the arched 

 brickwork cells in which the sand is stored, 

 there is a series of capacious cylindrical 

 vessels that perform an important part in the 

 economy of the manufacture, being none 

 other than the boiling down of veritable flint 

 " nubblocks." The flints are combined with 

 a certain proportion of caustic soda, and the 

 heat is applied by steam under pressure of 

 from 60 lb. to 80 lb. per square inch. The 

 product of the flint dissolved in caustic soda 

 is silicate of soda, which constitutes the 

 cementing agent in the first stage of moulding 

 the stone. When the contents of the 

 digesters have been dissolved it is drawn off", 

 and subjected to evaporation till it reaches a 

 specific gravity of about r.700, when it is 

 ready for use ; it contains about two-thirds 

 silicate and one-third soda. The glassy, 

 treacly, semi-fluid is then mixed with a suit- 

 able proportion of the sifted and dried sand, 

 and after thorough incorporation in a pug 

 mill the mixture is ready for the moulders, 

 to whose benches it is conveyed, and by 

 whom it can be fashioned into any desired 

 form. Thus far, after being moulded, a stone 

 has been produced, capable of hardening by 

 desiccation ; but the silicate which binds 

 together the particles of sand is soluble, and 

 the stone in this state would not resist the 

 action of water. The most important step in 

 Mr Ransome's progress, in which his chemical 

 knowledge stood him in good stead, was the 

 means he adopted for converting the soluble 

 silicate of soda into an insoluble silicate of 

 lime, which is accomplished by saturating 

 the moulded stone in a solution of chloride of 

 calcium. The chemical result of such satu- 

 ration is a reciprocal action, the products of 



which are an insoluble silicate of lime and 

 chloride of sodium, or common salt ; the one 

 binds the particles together indissolubly, the 

 other is removed, as it exudes to the surface, 

 by copious washing. 



It would occupy more space than you can 

 spare to attempt an enumeration of the 

 variety in character, uses, and destination of 

 the productions of this establishment. 

 Amongst other objects under the hands of 

 the workmen, were the plain and the orna- 

 mental. In one place the material, plastic 

 now, wasbeinghard rammedupon aperforated 

 iron table, into circular moulds that indicated 

 the various sizes of grindstones in progress. 

 When the ramming and top rolling is com- 

 pleted, the holes between the stones on the 

 table are plugged, and air pumps applied to 

 the masses remaining on the tables, by which 

 the process of saturation with the chloride of 

 calcium is greatly facilitated. In another 

 place chimney pieces with beautifully sharp, 

 delicate, enriched mouldings, were in 

 progress ; and in another, portions of 

 a large fountain, destined for Jamaica. 

 The details of this structure in separate 

 pieces, consisting of dolphins, aquatic plants, 

 shells, and other appropriate objects were 

 exquisite specimens of design and skill in 

 execution. In other parts of the works, 

 flooring-tiles of different colours, and in their 

 finished state of almost adamantine hardness, 

 were being rolled instead of rammed ; and 

 on other benches emery discs for saw- 

 sharpeners were being rammed, and also 

 rolled, and turned out of the moulds very 

 deftly, by means of very ingenious yet simple 

 appliances. These discs, which are a curious 

 application of the Ransome process, are won- 

 derful in performance. One of them about 

 Yz an inch thick, was shewn in action upon a 

 file of about 5^ -inch thick, which it ground 

 down as if it had been a piece of soft slate, 

 while it operated until the file was red 

 hot, and had a long thick train of brilliant 

 sparks thrown from it, the disc itself remained 

 so cool as to be touched with perfect im- 

 punity. We are informed that one of these 

 discs 54^-in. thick will attack a saw blade ^-in, 

 thick and cut it at the rate of 6 inches per 



