362 



POTTKHV 



, on its lower side. This plate is cut to the out- 

 line of half the plato, or dish ; as it revolves, this 

 pares down and shapes the clay to it* own outline, 

 and to the thickness to which 

 it U set, there U-ing an arrange- 

 ment on the ann of the guide 

 post by which this can lie 

 effected. Sometimes, as in tin- 

 case of deep vessels, moulds are 

 used for the exterior, and the 

 interior is formed by the hand. 

 This process (tig. 9) ensures 

 certainty of size and shape, 

 which is important in making 

 large numbers of similar articles, 

 as tea-cups, \-e. The mould is 

 lined with a thin cake of clay, 

 and when placed on the revolv- 

 ing disc it is fashioned inside 

 by hand, and finished off with 

 awetsponge. Sometimes metal 

 or horn tools are used for pro- 

 ducing mouldings and other raised ornaments, or 

 for grooves, when the turning or throwing wheel is 

 used. 



Being formed, the articles, of whatever kind, are 

 now taken to the drying-stove, where they are 

 placed on shelves, and remain there some time, 

 exposed to a heat of about 85 P. When quite 

 dry, they are next taken to a workshop near the 

 kiln, and they are here carefully pocked in coarse 

 earthenware vessels, called teggart (fig. 10), which 

 are so made that they can be piled upon one 



Fig. 10. 



another to a great height in the kiln, as seen in 

 fig. 11, in which some of the seggars are shown in 

 section, for the purpose of making the arrangement 

 intelligible. As the seggars are generally made 

 large enough to hold a number of articles, which 

 would, when highly heated, adhere if they touched, 

 a number of curiously shaped pieces of burned clay 

 are used for placing l>etween them, so as to make 

 them rest on points; these are called tmtc/irs, 

 cocktpurt, triangles, tliltt, &c. (lig. 12). In the 

 eggar filled with plates (fig. 13) the plates are 

 een each resting on cocktpurt, which prevent tln-m 

 touching. Another object is gained by tlii- in 

 h-irning Hat articles such as plates; these," if placed 

 one upon another, would not be fired equally, but 

 when they are held apart the heat affects all parts 

 alike. The seggars are so piled in the kiln that 

 the centre is hollow, and there are free spaces 

 between them through which the fire can ascend : 

 props, n, n, n, lig. II, lining KO placed as to keep 

 them froin immediate contact with the sides all 

 round. Tims each soggar forms a small oven, in 

 which one or more pieces of |,<ittery or porcelain 

 are Inked, and the Beggars prevent any unequal 



heating of the pieces, and also protect them from 

 smoke. A kiln has generally eight furnaces, and 

 it is usual to raise six piles of seggare between 

 every two furnaces, or rather between their flues, 

 which rise to a considerable height in the kilns. 

 Each pile of Beggars is technically called a bung, so 

 that there are generally forty eight or fifty bungs 

 to the charge of a kiln. When all this is arranged 

 the furnaces are lighted, and great care U taken to 



FSg.ll. 



use the best coal, as it enables the manufacturer 

 to make a more certain calculation as to its effects, 

 and is less liable to smoke and sulphurous vapours, 

 which might injuriously affect the contents of the 

 kiln. The baking or firing usually lasts from forty 

 to forty-two hours. The hre is then allowed to go 

 out, and the kiln to cool very gradually, after 

 which it is opened, and the seggars removed, to be 

 unpacked in a separate workshop. 



The articles are now in the state called biscuit- 

 ware, and are ready for any pattern they may lie 

 intended to bear, and the glaze. Here, however, it 

 may be stated that it is possible to glaze refractory 

 pottery, such as stoneware in the biscuit oven, and 



Fig. 12. 



thus avoid the necessity for two firings to the ware. 

 The glazing is in this case effected by throwing 

 common salt into the oven when at its highest 

 temperature. The salt is volatilised and the sodium 

 separates from the chlorine, and, combining with 

 the silica it finds in the heated ware, forms a 



