POTTERY AND PORCELAIN. 455 



whiteness and lustre. As these last qualities, howerer, are es. 

 teemed most essenthl. that of infusihility (which indeed is of no 

 great consequence for any of the common uses of porcelain) hai 

 been sacrificed ; and hence those that make a near approach to 

 the oriental in beauty and delicate lustre, of which many manufac- 

 tures in different parts of Europe have afforded splendid examples, 

 are frequently found to suften and melt down in an intense heat of 

 a wind-furnaie, at which the true Nankin and Japun china undergo 

 no change. 



The manufacture of the ordinary pottery is on the whole very 

 simple where a due selection of materials is made ; but the orna- 

 mental branches of it, such as those of modelling, enamelling, 

 painting, and gilding, which often display exquisite beauty, are 

 accompanied with much delicacy, and require a combination of 

 perseverance, skill, and practical nicety of management, that are 

 rarely equalled in any other chemical manufacture. 



An intimate mixture of the ingredients used in pottery is of 

 great importance to the beauty, compactness, and soundness of the 

 ware. Formerly the wet clay and ground flint, or whatever else 

 was employed, were beaten together with long continued manual 

 labour, no more water being added than was necessary to render 

 the clay thoroughly plastic. This laborious and expensive method 

 has now been laid aside in the larger potteries ; and the ingenious 

 method has been substituted of bringing each material first to an 

 impalpable powder, and diffusing them separately in as much wa- 

 ter as will bring them to the consistence of thick cream, mixing 

 them in due proportion by measure, and when thoroughly stirred 

 together, evaporating the superfluous water till the mass is brought 

 to a proper consistence for working. 



In the Staffordshire process the materials are a fine clay, brought 

 chiefly from Devonshire, and a siliceous stone called chert, or else 

 common flint reduced to p.owder by heating it red-hot, quenching 

 it in water, and then grinding it by windmills. Kach material is 

 passed through fine brass sieves, then diffused in water, mixed by 

 measure, and brought to a plastic state as above. 



The wheel and lathe are the chief, and almost the only, instru- 

 ments made use of : the first for large works, and the last for 

 small. The potter's wheel consists principally in the nut, which is 

 a beam or axis, whose foot or pivot plays perpendicularly oo a 

 free-ston esole or bottom. From the four corners of this beam, 



