228 THE WEDGWOODS. 



"CATJLUf. 



"This material, in the Chinese way of speaking, constitutes the 

 bones, as the Petunse does the flesh, of china-ware. It is a white 

 talcy earth, found in our granite countries, both in the counties of 

 Devon and Cornwall. It lies in different depths beneath the sur- 

 face. Sometimes there shall be a fathom or more of earth above it, 

 and at other times two or three feet. It is found in the sides of 

 hills, and in valleys; in the sides, where, following the course 

 of the hills, the surface sinks, or is concave, and seldom, I believe, 

 or never where it swells, or is convex. By what I have observed, 

 it is by no means a regular stratum, but is rather in bunches or 

 heaps, the regular continuance of which is frequently interrupted 

 by gravel and other matters. At times there are veins of it among 

 the solid rocks, when it is constantly very pure from gravel. I 

 have a piece by me of this kind, very fine. 



" There are inexhaustible stores of this Caulin in the two western 

 counties. The use it's commonly put to is in mending the tin 

 furnaces and the fireplaces of the fire-engines, for which 'tis very 

 proper. The sort I have chiefly tried is what is got from the side 

 of Tregonnin Hill, where there are several pits of it. As the stone 

 hath a pretty large quantity of Caulin in it, so the Caulin hath a 

 large mixture of the same sort of gravel as enters into the compo- 

 sition of the stone. It contains, besides, mica in abundance. 



"In order to prepare the Caulin for porcelain, nothing more is 

 necessary but pouring a large quantity of water on it, so that it 

 may not, when dissolved, be of so thick a consistence as to suspend 

 the mica. Let it settle about ten minutes, and pour off the dis- 

 solved clay into another vessel. Let it settle, pour off the water, 

 and dry it. I would observe here, that care ought to be taken about 

 the water used in washing off both the Petunse and Caulin. It 

 ought to be pure, without any metallic or calcareous mixture. Our 

 rivers in the west afford excellent water for this purpose, as they 

 arise, the most of them, and run through a granite country. The 

 Caulin of Tregonnin Hill is very unvitrifiable, and exceedingly apt 

 to take stains from the fire. I know no way to keep it clean but the 

 following : Form it into cakes of the thickness of two or three crown 

 pieces, and beat some of the stone to a very coarse powder ; cover 

 the bottom of the crucible with this powder ; then put in a cake 

 of the Caulin; cover this the thickness of one-third of an inch 

 with the powder of stone ; fill the crucible in this way, ending 

 with a layer of the stone ; cover the crucible, and treat it as in the 



