608 Kaolin and other Clay. 



the vicinity of coalfields. There iron furnaces glare 

 and blow day and night, there are carried on vast 

 manufactures in all kinds of metal, and there our 

 textile fabrics are chiefly made. In these busy scenes 

 a large part of the population of our island finds em- 

 ployment, and thence we send to the farthest parts of 

 the earth those endless commodities which, while they 

 have supplied the wants of other countries, have given 

 rise in large measure to the wealth and commerce of 

 our own. 1 



There are some other geological formations which 

 afford materials for manufactures other than coal and 

 ores of metals. Thus, in the south-west of England, in 

 the granitic districts of Devon and Cornwall, a great 

 proportion of the finer kinds of clays occur, which are 

 used in making stoneware and porcelain. In Devon 

 and Cornwall the decomposition of granite affords the 

 substance known by the name of Kaolin, from which 

 all the finer porcelain clays are made. It is formed 

 by the disintegration of the felspar of granite. This 

 felspar consists of silicates of alumina, and soda or 

 potash. The soda and potash are comparatively easily 

 dissolved, chiefly through the influence of carbonic acid 

 in the rain-water that falls upon the surface ; and the 

 result is that the granite decomposes to a considerable 

 depth. In some cases I have seen granite, undisturbed 

 by the hand of man, which for a depth of twenty feet 

 or more might be easily dug out with a shovel. Owing 

 to this decomposition, a portion of the felspar passes 

 into kaolin, which is washed down by rain into the 

 lower levels, where, more or less mixed with quartz 



1 At least it was so till lately, and there is no reason to suppose 

 that the mining and manufacturing industry of Britain has de- 

 clined except for a time. 



