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Class 1.—MINING- AND MINERAL PRODUCTS.South Side—Areas S. 1 to S. 27.

[United

[The china-clay and'china-stone used in the manufac-ture of the finer kinds of porcelain are chiefly obtainedfrom decomposed granite; the felspar of the granite, undercertain circumstances, yielding to the action of the wea-ther, and parting with its alkaline earths, and the harder,heavier, and coarser parts of the granite removed by me-chanical washing, either naturally or artificially. Thepurified material thus obtained is called kaolin ; its specificgravity is from 2*21 to 2 * 26 . Some of the finer kinds con-tain, when boiled for a short time in a solution of potash,about equal parts of silica and alumina, upwards of 10per cent, water, and from 2 to 10 per cent, of free silica;the mineral being therefore represented by the formulaA : S : + 2 Aq.

The formula for felspar is 3 A: Si 3 -f K: Si a, the potashbeing often replaced by soda, and the nature of the changemay thus be understood. The best china-clay in Englandis obtained from Cornwall and Devonshire.—D. T. A.]

102 Pike, William & John, Wareham , Dorsetshire —

Producers.

Potters’ or blue clay, from the island of Purbeck, Dor-setshire, used in British and foreign potteries.

[The greater part of the best pottery produced invarious parts of the world has Dorsetshire clay for itsprincipal ingredient. Blue, or potter’s clay, for makingfine ware, should mix tough, be free from sand, burn agood colour, and bear a large proportion of flint. Thisclay is said to possess these qualities; and a piece ofearthenware made by Messrs. T. J. and J. Mayer is exhi-bited, which contains no other but china-clay.]

Stoneware clay, used in the London and Bristol pot-teries for the manufacture of stoneware and drain pipes.

Pipe clay, for the manufacture of tobacco pipes.

Alum clay, for the manufacture of alum.

[A considerable quantity of clay fit for ordinary potters’work, and for the manufacture of tobacco-pipes, besidessome alum schist, is obtained in the small peninsula calledthe isle of Purbeck, on the Dorsetshire coast. This littletract of land contains a curious series of cretaceous, Weal-den, and oolitic deposits; among the latter is the Kim-meridge coal elsewhere described, and above the wholeseries are clays of the Hampshire basin, in the manufac-ture of which the coal is used. These plastic clays belongto the lowest tertiary deposits.—D. T. A.]

103 West of England China Stone 8c ClayCompany, St. Austell , Cornwall — Producer.

Specimens of china-stone and clay in the different stagesof the process to which it is subjected prior to its beingsent to the potteries and bleaching manufactories invarious parts of the old and new world.

They are obtained from the most extensive and ancientchina-stone quarries and fallow clay beds in Cornwall .The Company holds the exclusive right of working over3,000 acres of this county. These products have takenthe first position in the markets hitherto, especially inStaffordshire , where they are most extensively used, andhighly valued.

The china-stone is exhibited in the state in which itnaturally occurs; it forms the partially-decomposed gra-nitic ranges which stretch through the centre of Cornwall ,where quarries are formed for the purpose of raising it:and next in the state after it has been subjected to theheat of the oven for the purpose of testing its vitrifyingproperties.

The china-clay, or still further decomposed granite(the china-stone being, as it were, an intermediate stage),is found in large beds, where it is mixed up with thesand which formed a component part of the granite: thisis termed the clay stope, of which there are one or twospecimens; by trituration with water the clay is sus-

pended and carried off from the sand, which is depositedin the passage of the clay water, to the pits in which it isallowed to stand, so that the suspended particles mayfall to the bottom, and the supernatant liquor flow off;the clay deposit is then placed in pans, exposed to thewarmth of the sun, and bleaching power of the atmo-sphere; when thoroughly dry, it is sent to the potteriesin the state shown in the case, in large heaps of about1 foot square: the process to which it is next subjected,that of burning, serves as the best test of its quality,—inwhich state there are one or two samples; and lastly,the combination of clay and stone shown in the manu-factured article, the china cards of the Company.

104 Truscott, Charles, St. Austell —Producer.

Cornwall china-stone in its native state; as calcined; asground; and as ground and calcined. Cornwall china-clay in its native state; as calcined; in a state for porce-lain ; and in a state for bleaching and paper manufacturingpurposes.

105 Grimsley, Henry, Oxford — Designer andModeller.

Terra-cotta statue of a female figure holding a dial, madein clay obtained from Shotover Hill, near Oxford . Clay,sand, and ochre, from the same place, showing fourteendifferent strata, to the depth of 25 feet.

106 Burnett, Nicholas, Black Hedley, Gateshead ,Newcastle-upon-Tyne —Producer .

Specimen of clay, found near Black Hedley.

Articles manufactured from the clay, by Messrs. Thos.Fell and Co., Newcastle .

[This clay is of particularly fine quality, and the mate-rial manufactured from it exhibits marks of this in thesurface it presents, and its uniform tint.—D. T. A.]

107 Martyn, Elias, St. Austell —Producer andManufacturer.

Specimens of china-clay, or kaolin, used in the Stafford-shire potteries, in bleaching, and in paper-making.China -stone.

108 Wheeler, Philip, 8c Co., St. Austell —

Proprietors.

China -clay, or “kaolin,” for the manufacture of earthenand china ware.

Bleaching clay, used in the cotton and paper manu-factures.

Clay, exported to France , &c., for the extraction andmanufacture of alum.

China stone from quarries in the parish of Germoe,Cornwall .

[The china-clay quarries in the adjoining parishes ofGermoe and Breage, were the first worked in this country;and from this clay the earliest Plymouth china was made.—R. H.]

109 Browne, William, St. Austell —Proprietor.

Specimen of china-clay, derived from the decomposition

of felspar, extensively used in the manufacture of china,porcelain, and parian, for ornamental vases, busts, andall articles that require particular care and delicacy inmoulding; and employed in the patent manufacture ofornamental stone, facing, flooring, and tiling, variousarticles of furniture, &c.

[A very large quantity of valuable china-clay and china-stone are found naturally, and prepared artificially inCornwall and Devon, chiefly from the St. Austell decom-posing granite, and the southern granite of Dartmoor.About 14,000 tons of prepared and 30,000 tons of naturalchina-clay are annually exported, chiefly to the potterfes,-D. T. A.]