Page:The Building News and Engineering Journal, Volume 22, 1872.djvu/230

 214 THE BUILDING NEWS. Marcu 15, 1872. ‘improved compounds or compositions in imi- tation of marble, veneer, and other substance used in the manufacture of fancy and other articles,” &c. He says: ‘‘ My improved com- pounds or compositions are intended to be used in imitation of marble and veneer, and other substances, and may be manufactured in various ways and of various ingredients: a tabular list of which, with their approximate proportions and the different processes I employ for the manufacture of each compound being given below :— “No. 1.—I take of glycerine, 2; glue, 6; resin, 14; water, 14; solution of potash or soda, 4 parts. ‘“‘T first dissolve the glue in water, then boil the resin in the solution of potash or soda, until it is reduced to the consistency of a jelly. I add these two mixtures together, and then mix therewith the glycerine, and allow the whole mass to simmer for a few minutes, any desirable colour being added to the mixture, when in a liquid state, to repre- sent the required ornamentations. ‘* No. 2.—I take of glue, 2; resin, 1; oil, 1; solution of potash, 3; lime water, 4 parts. the resin in the oil, then mix therewith the potash or soda, and allow the compound to simmer for a desirable length of time, and I add to the compound any desirable colour to imitate veneer, marble, or other substance. “No. 3.—I take of gum arabic, 10; water, 20 parts. Carbonate of lime according to re- quirement. “JT dissolve the gum in the water, and add any desirable quantity of lime, and mix there- with the colour required. “No, 4.—I take of oil, 1; carbonate or sul- phate of lime, 4 parts. “T grind these substances well together, and mix therewith any suitable colour. ‘« No. 5.—I take of gold size, 1; dryers, 2; glue, 2; water, 6 parts. ‘*T dissolve the glue in the water, then add the gold size and dryers, and mix therewith any desired colour, as before mentioned. The colours are mixed with the various gluti- nous compounds or compositions, by twisting and pressing them into intimate contact with each other, between the fingers or by other suitable means, whereby streaks or veins of colour or other desired device may be pro- duced in the composition in imitation of ve- neer, marble, and other substances having ornamental surfaces. The said compounds or compositions may be laid on to wood, or other material required to be ornamented, either in a soft and moist state, and after- wards rolled out thereon to a smooth surface, or they may be first rolled out into a slab or sheet, and attached to the surface to be orna- mented by glue or other adhesive substance. These compounds may be made perfectly waterproof by adding thereto oil, gold size, or other waterproofing substance, as in com- positions Nos. 2 and 5, and they will not crack or warp, as ordinary veneers are apt to do— by change of temperature or other external causes—moreover, if any part of such com- position should by rough usage be chipped off, it can be readily replaced in perfect har- mony with the remainder of the veneer. The slabs or sheets may be rolled out by hand, or by placing them between a pair of revolving cylinders, and may be made in any suitable shape or form to suit the article desired to be ornamented therewith. The surface of the veneer is capable of receiving a very high polish, and I prefer to prepare the surface for this polish by rubbing it when hard with pumice stone and rotten stone and oil until it becomes perfectly smooth. I then apply to this smooth surface ‘French,’ or other desirable polish in the ordinary way. I claim the improved compounds or compositions herein specified, and their applications to the manufacture of fancy and other articles.” So far Mr. Edward Snell, who does not tell us definitely or positively how the various coloured compositions are put together to form imitations of marbles. But we gather from the other patent on the same subject before referred to, that each mass of coloured composition, after being kneaded well, is kept covered with a wet cloth, which keeps it ina moist and workable state. A portion of such of these coloured compositions as may be required for the pur- pose ia hand, are taken and worked or kneaded together, forming a variegated mass, which, when rolled out into thin sheets or slabs, are marked or veined in accordance with the skill or taste of the operator, and in any colours, as may be desired. ‘These methods of imitating marble haye many very excellent points about them, and are very useful as a substitute, but their great point of failure is their want of transparency ; we know of no real marble in which this quality is absent. As we have before said, we have a large number of variously coloured marbles at our command: of these we may note those which are most in use for architectural pur- poses Several of these have been long knownand used in England, such as Sienna, a useful and beautifully coloured and veined yellow marble, got from quarries in the neighbourhood of Sienna; and it may be here noted that mostmarbles receive their com- mercial names (if we may sospeak) from the locality or place from whence they come. Sienna marble varies very much in colour and marking, some blocks being light and quiet m the markings and colour of the veins, while others will be exceedingly strong in dark yellow and pink or red patches, and blue, black, or purple veins. Inother blocks the yellows will have a dirty stone-colour hue. So that, whether we are about to veneer a staircase with the real marble or to paint an imitation, it will require the marble to be selected with a view to avoid the patchy look it would otherwise have if dark and light coloured slabs were used indiscriminately. Sienna is a marble admir- ably suited for using in large masses, and for contrasting with other marbles, either in large or small quantities. Brocatella is another yellow marble much more broken up and smaller in its markings than Sienna, very suitable for using in combination with other marbles, but not in large masses. Of this marble there are two or three varieties. One kind in which veins and patches of gray or violet prevail, and is hence callen Brocatella violette. Most of the Brocatellas are got from Spanish quarries. Another marble suitable for using in large masses on staircase walls, and also for inlay- ing, is what is called by painters Italian pink, bnt it isin reality the lighter blocks of the Breechi Imperiale, or, we believe, there are quarries of this marble in Belgiwn. The Breech marbles vary in colour from a deep dull red to a beautiful light pink, with red, purple, gray, and yellow veins, and are broken up into large and small angular pieces, which appear to have been at one time in large sheets or blocks, and to have been broken up and floated together, the small pieces congre- gated together between the interstices of the larger ones, and so petrified again. ‘That this has been the case the appearance of the marble indicates. Italian pink is a beautiful marble for use in any large masses, such as staircase walls and centres of large panels, in- laying with other marbles being essentially different, both in colour and character, to Sienna. Painters work the same marble in gray tints on staircase walls in imitation of Breechi violette, which make a pleasing marble for a large mass, but is rather cold in effect. The darker kinds of the Breechi marbles are, in the larger patches, of a dark dull purple brown, intermixed with small patches of light colour; it is admirably adapted for pilasters, chimney-pieces, and inlaying. | (Zo be continued.) HOW TO BUILD SCIENTIFICALLY WITH THE AID OF MODERN IN- VENTIONS.—VII. WALLS, ERRA-COTTA.—Haying shown in the previous chapter that we are considered a brick-building and brick-loving nation, it will certainly appear surprising that for centuries the complement of brick—namely, terra-cotta, has been comparatively unknown amongst us, and that it is only of late years that the attention of architects has been again directed to this material I have nothing to do with the history of terra-cotta, or I might allude to the beautiful buildings of North Italy ; and, beginning yet earlier, trace terra-cotta works from Egyptian times, through the Grecian and Roman periods, and thence to the works produced in England, of the thirteenth and the sixteenth centuries ; but I am dealing only with the use that can now be made by the architect with the materials at his command, that he may build most scientifically and economically. Description—As its name implies, terra- cotta is composed of baked or burnt clay, which should be of the finest quality. Materials—Mr. Barry, in his elaborate paper on this subject, says the materials used are the clays of Cornwall, Dorset, and Northamptonshire ; Lynn sand, ground glass, china, stone, felspar, and flint; also broken terra-cotta, or burnt ware pulverised. For very light porous articles fossil bone is used with terra-cotta. The variation of colour in white, buff, and red terra-cottas is due to the clays ; other colours, such as black, grey, green, blue, &c., are obtained by the admix- ture of mineral colours with clays and other substances forming the body of the ware. Filling in.—Roman cement should be used where necessary, and not Portland cement, because the latter swells in setting, and would crack the terra-cotta columns, &e. Cost-—Every writer on this subject that I know of says tlie cost of this material would be largely reduced if it became more generally used. There is no doubt that one item of that cost might be much reduced. I allude to the mason’s work when the material is hard and dry, before it is burnt, which is at present required to make the blocks or mouldings true and square in their arrises and other parts. ‘This would appear something that science should render un- necessary. Mr. Barry’s experience at Dul- wich College is thus expressed: ‘‘ Speaking in general terms, I think I may say that, taking cube for cube as fixed in a building, terra-cotta costs a little less than the soft stones, as Bath, Caen, &c., while as regards Portland, the average difference would be about 35 to 40 per cent. The greatest eco- nomy is to be found where there is much work either in under-cutting of mouldings (which costs nothing extra in terra-cotta over ordinary mouldings), and in artistic modelled work ; when, as [have already said, under-cutting and almost full relief of fea- tures is as cheaply produced as low relief. In these cases the economy is often Several hundreds per cent. over hard stone. Plain strings, friezes, and plinths cost compara- tively more in terra-cotta than other and more enriched works in the material.” He further gives the cost of the ground-floor window in a bay of the facade of the north and south wings of the college. ‘The cost, made and fixed complete, was, £19; if in Bath stone it would have been £20; and if in Portland stone, £28. The cost of solid terra-cotta blocks, in ordinary colours, is about 3s. Gd. per foot cube. If hollow, and filled in with broken terra-cotta or brick in Roman cement, the cost is about 3s. 1d. per foot cube. Advantages.—Great durability, non-absorb- ing qualities, power of resisting discolouration, economy, colour, cost of carriage. ‘“
 * T dissolve the glue in the lime water, and