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process for melting the stone before described. If the stone is 

 burned to purity, the Caulin will be as white as snow ; if but par- 

 tially calcined, so far as the stone is pure, the Caulin will be so ; 

 and when that is of a dirty colour, the Caulin will be of the same 

 hue. 



"I have lately discovered that, in the neighbourhood of the 

 parish of St. Stephen's, in Cornwall, there are immense quantities 

 both of the Petunse stone and the Caulin, and which, I believe, 

 may be more commodiously and advantageously wrought than those 

 of Tregonnin Hill, as, by the experiments I have made on them, 

 they produce a much whiter body, and do not shrink so much, by 

 far, in baking, nor take stains so readily from the fire. Tregonnin 

 Hill is about a mile from Godolphin House, between Helston and 

 Penzance. St. Stephen's lies between Truro, St. Austel, and St. 

 Columb ; and the parish of Dennis, the next to St. Stephen's, I 

 believe, hath both the ingredients in plenty in it. I know of two 

 quarries of the stone one is just above St. Stephen's, the other is 

 called Caluggus, somewhat more than a mile from it, and appears 

 to be the finer stone. 



" Having given this sketch of the natural history of the materials, 

 'tis needless to say much about the composition. Pottery being at 

 present in great perfection in England, our potters' -mills prepare 

 the Petunse much better than stamping mills, and excuse one from 

 the trouble of washing it off, it being fit to be used as it comes from 

 the mill. I would further observe that the mills should be made of 

 the Petunse granite, it being obvious that, in grinding, some of the 

 mill-stones must wear off and mix with the Petunse. If those 

 stones should be of a nature disagreeable to the body, this mixture 

 must, in some degree, be hurtful to it; whereas, whatever wears 

 off from mill-stones of the same stone, cannot be so in the least 

 degree. I have generally mixed about equal parts of the washed 

 Caulin and Petunse for the composition of the body, which, when 

 burnt, is very white, and sufficiently transparent. The Caulin of 

 St. Stephen's burns to a degree of transparency without the addition 

 of Petunse. The materials from this place make a body much 

 whiter than the Asiatic, and, I think, full as white as the ancient 

 china-ware, or that of Dresden. 



" The stones I have hitherto used for glazing are those with the 

 green spots of Tregonnin Hill. These, barely ground fine, make a 

 good glaze. If 'tis wanted softer, vitrescent materials must be added. 

 The best I have tried are those said to be used by the Chinese, viz., 

 lime and fern-ashes, prepared as follows : The lime is to be slaked 



