CLICHY WHITE 815 



St. Agnes Clay. 



9 " Tons 



Shipped for Wales, 1865 . . . . . . 1,566 



Do. 1866 . . . . . . 1,524 



Do. 1867 1,316 



Do. 1868 979 



Do. 1869 875 



Do. 1870 946 



Do. 1871, year ending March 3 1st. . 774 



Do. 1872 1,201 



Do. 1873 1,657 



Candle Clay used in the Mines 1871, year ending Sept. 30 . 

 ,. 1872 



DEVONSHIRE. 

 China Clay. 



Lee Moor and other China Clay Works, on Dartmoor, 1872 .... 26,982 

 Pipe and Potters' Clay shipped at Teignmouth, the production of Newton and 



Neighbourhood 52,141 



Total of Devonshire 79,123 



Of Potters' Material there were imported into the Potteries by Trent and"! 

 Mersey Navigation, (Clay, &c.) . . . . . . ./ 



And by North Staffordshire Kailway, (Clay, &c.) ..... . . 12,479 



CXiAT IRON" STONE. See IKON OHES. 



CLAYITE. A variety of Galena. See LEAD. 



CLAY SLATE. Argillaceous Schist. See SLATE. 



CXiAYSTONE. An earthy felspathic rock, occurring in veins and in mountain 

 masses. It becomes porphyritic by the intermixture of felspar crystals, and is then 

 known as Claystone porphyry. 



CZjEAT. It is well known that most coals have a tendency to split not only 

 along the plane of bedding, but also along two sets of divisional planes, nearly at right 

 angles to the bedding and to one another. The coal may thus be split into rough % 

 cuboidal fragments. One of these two sets of vertical planes is much more marked 

 than the other, and the smooth clean surface of the coal coinciding with this well- 

 defined set of joints is known as the cleat, face, or slyne ; whilst the other vertical 

 surface is called the end or back of the coal. The direction of the cleat is often 

 constant over a largo area, and advantage is taken of this constancy in laying out the 

 workings of a colliery. 



CUBA V AGE. The tendency of a crystal, or crystalline substance, to split more 

 readily in certain directions than in others. The property was originally observed in 

 calc-spaj (carbonate of lime), a mineral which crystallises in a great variety of 

 external forms, but may always be readily cleaved along the planes of a definite 

 rhombohedron. The natural cleavage of a mineral is frequently taken advantage of 

 by the lapidary, in cutting hard stones ; thus, a crystal of diamond, though excessively 

 difficult to cut, can be very easily split or cleaved parallel to the faces of a regular 

 octahedron. 



By geologists, the term cleavage is used in a different sense. Certain rocks, such as 

 slate, exhibit a tendency to split into very thin parallel plates, and the direction .of 

 this cleavage is often constant throughout great masses of rock. This slaty cleavage 

 is not to be confounded with the ' lamination ' of a rock, or the facility with which it 

 divides into parallel laminae along the planes of stratification. The cleavage, though 

 it may accidentally coincide with the bedding, usually cuts across it, at various 

 angles, and is evidently a structure superinduced in the rock after its original 

 deposition. Physical researches on this subject have shown that slaty cleavage may 

 be developed by lateral compression, the direction of the planes of cleavage being at 

 right angles to the direction in which the pressure has been applied. The ordinary 

 clay-slates used for roofing are prepared by splitting the mass along its planes of 

 cleavage. 



CI.ICHY WHITE. A white lead manufactured at Clichy in France. See 

 WHITE LEAD. 



