Kingdom.]
131
Class 1.—MINING AND MINERAL PRODUCTS.South Side—Areas S. 1 to S. 27. .
[The well-known Stourbridge fire-clay consists of amaterial of considerable purity, existing in beds under-lying coal in the coal-measures of the district. Similarbeds of fire-clay, though rarely so good, occur elsewhere,and are extensively worked; but none have attained a. reputation equal to that of Stourbridge in the manufac-ture of retorts and other fire-clay goods which have tosustain long-continued and intense heat. The chief ex-cellence consists in the absence of iron and of alkalineearths (which would produce fusion of the clay), and acertain amount of porosity admitting of a little expansionand contraction. In the raw goods, the quality is notseen, but in those that have been fired, paleness of colourand the absence of cracks are considered good marks ofexcellence.—D. T. A.]
92 Jenkins & Beer, Truro —Producers.
Ochres, three in a powdered state, of different shades ofcolour, and one in lumps of two shades of colour; pro-duced at Kea, near Truro; used in the manufacture ofpaints, paper-hangings, &c. Exhibited on account oftheir clearness, fulness of colour, body, and cheapness.
93 Jenkins & Courtney, Truro —Producers.
Specimens of Cornish china-stone, exhibiting its
natural fracture: raised in the Great Bodilla cliina-stonequarries, St. Stephen’s, Cornwall , and largely used inthe potteries for the manufacture of the finer descrip-tions of china and earthenware.
[China-stone and china-clay, both of which are mostextensively used in the potteries, are produced in theneighbourhood of the great granite ranges of Cornwall and Devonshire: in the former county chiefly from theSt. Austell granite, and also from Tregorming Hill tothe south of Helstone, and from the southern granite ofDartmoor in the latter county. The decomposed graniteof St. Stephen’s, and the uses to which it and the clayproduced from it could be applied, were discovered in17G8 by Cookworthy of Plymouth , who was the firstperson who made hard porcelain in this kingdom. To thisdiscovery is due entirely the manufacture of porcelain,similar to that of china.
The composition of this kaolin, or porcelain clay, variesin different localities, the average of the best Cornishclay giving an analysis—alumina, 24*6; silica, 44-30;lime, magnesia, and potash, 1*60; water, 8*74. The purekaolin of Dartmoor being, alumina, 36*81; silica, 44*25;lime, magnesia, and potash, 2*20; water, 12*7.
With the increase of our porcelain and fine earthen-ware manufacture, the demand for these clays has largelyincreased; and to this must be added a large trade inthe china-stone itself, which is used principally forglazing fine ware, the ordinary glaze being composedof decomposed granite, lime, flint, litharge, and borax.
A large quantity of this clay of an inferior quality isused by the paper-makers and calico-dressers, for thepurpose of giving weight and body to their fabrics.
Men, women, and children are largely employed onthese clay-works, which, when the clay is being dressed,present a scene of active and curious industry.—R. H.]
04 Thriscutt, C., St. Austell-— Producer.
China-clay as dug out of the earth, from CaudledownClay-works; prepared, burned, and calcined.
05 Whitley, N., Truro —Producer.
Clays of the district of Truro.
97 Minton, H. & Co., Stoke-upon-Trent —Manufacturers.
A collection of the various materials used in the manu-facture of all kinds of porcelain and earthenware.
1. Raw material.— Cornish clay in its natural state; andthe same prepared for use; both from the Cornish ClayCompany; the same fired. Cornish clay as prepared at Mr.Thriscutt’s works, Caudledown; the same fired. Cornishstone from the Cornish Clay Company; the same groundand fired. Swedish felspar; the same ground and fired.Blue clay, from Fayle’s works, Dorsetshire , in the rawstate; the same fired. Blue clay from Whiteway’s worksin Dorsetshire ; the same fired. Gravesend flint in itsnatural state. Flints calcined. Flints calcined andground.
2. Glazing Materials .—East Indian tincal, or borax inits imported crude state. Boracic acid. Borax crys-tallized, from Mr. E. Woods of Liverpool. Oxide of lead.Fritt for glaze. Paris white. Soda. Potash. Niti*e.
3. Colouring Material .-—Oxide of copper. Protoxide ofnickel. Oxide of chromium. Oxide of tin. Peroxideof manganese. Oxide of zinc. Peroxide of cobalt.Smalt-blue. Oxide of antimony. Granulated gold.Granulated silver.
98 Highley, Samuel, jun., 32 Fleet Street —Importer.
Collection of rocks and fossils, stratagraphically ar-ranged, to illustrate modern works on geology; from Dr.Krantz’s establishment at Bonn .
99 Greaves, R., Warwick —Proprietor andProducer.
Two busts of Sliakspeare, in cement.
100 Fayle, Benjamin, Sc Co., Old Swan Lane , UpperThames Street —Proprietors.
Specimen of blue potters’ clay, as dug from the pitsat Norden, Isle of Purbeck, county of Dorset ; used forthe manufacture of earthenware; said to possess greaterstrength of body, and to shrink less than many otherclays when exposed to high heat.
101 Phillips, William, Morleg Works, near Plympion—Producer and Proprietor.
1. Specimen of disintegrated granite from MorleyWorks, Devon, in which the felspar is in a decomposedstate, pure, and in a large proportion, compared with thequartz, schorl, and mica.
2 and 3. Prepared china clay, or decomposed felspar,the result of washing; used chiefly in porcelain, fine andcommon pottery, calico-dressing, and paper-making.
4. Specimen of clay for fire-bricks and crucibles. °
5. Plymouth porcelain, made by Cookworthy , thediscoverer of china-clay in this country.
6 and 7. Porcelain made from Morley clay.
8 and 9. Pottery from this clay, made of 80 per cent, ofclay, with flint and china-stone.
[A large quantity of china-clay is found on the southside of the Dartmoor granite, the quality of the 'claybeing excellent, and the position exceedingly favourablefor the supply of the Staffordshire potteries by railwaycarriage. The china-clay of Devonshire possesses muchinterest, not only by its excellent quality, but also as thematerial from which Mr. Cookworthy , the first manu-facturer of porcelain in England, probably obtained hismaterial. The process of purifying china-clay is at presentsimply mechanical, but is capable of much improvement,and the coarse parts of the clay are well adapted to themanufacture of brick of various kinds. The china-clay isobtained from the decomposition of particular varieties ofgranite.—D. T. A.]
10 and 11. Pottery of ordinary manufacture, withsmall proportions of china-clay, flint, and stone.
12 and 13. Bricks made from clay.
14, 15, and 16. Pottery and china, illustrative of theapplication and uses of this china-clay, which has a largerproportion of alumina than other china-clays, and is freefrom metallic oxides.