“The account of the materials used by the Chinese is very justly given by the Jesuit missionaries, as well as their manner of preparing and mixing them into the China-ware paste. They observe, the Chinese have two sorts of bodies for porcelain; one prepared with Petunse and Caulin, the other with Petunse and Wha She or Soapy Rock. The Petunse they describe to be prepared from a quarry stone of a particular kind, by beating it in stamping-mills, and washing off and settling the parts which are beaten fine. This ingredient gives the ware transparency and mellowness, and is used for glazing it. The stone of this Petunse is a species of the granite, or, as we in the west call it, the moor-stone. “I first discovered it in the parish of Germo, in a hill called Tregonnin Hill; the whole country in depth is of this stone. It reaches, east and west, from Breag to Germo, and north and south, from Tregonnin Hill to the sea. From the cliffs some of this stone hath been brought to Plymouth, where it was used in the casemates of the garrison; but I think the best quarries are in Tregonnin Hill. The stone is compounded of small pellucid gravel, and a whitish matter, which, indeed, is Caulin petrified; and as the Caulin of Tregonnin Hill hath abundance of mica in it, this stone hath them also. If the stone is taken a fathom or two from the surface, where the rock is quite solid, it is stained with abundance of greenish spots, which are very apparent when it is wetted. This is a circumstance noted by the Jesuits, who observe that the stones which have the most of this quality are the most proper for the preparation of the glaze; and I believe this remark is just, as I know that they are the most easily vitrifiable, and that a vein of this kind in Tregonnin Hill is so much so that it makes an excellent glaze without the addition of vitrescent ingredients. If a small crucible is filled up with this stone, or a piece of it put in it, and exposed to the most violent fire of a good wind furnace for an hour, the stone will be melted into a beautiful mass; all its impurities will be discharged, one part of it will be almost of a limpid transparency, and the other appear in spots as white as snow. The former is the gravel, the other the Caulin, reduced by fire to purity. If the fire is not continued long enough to effect this, the upper part and middle of the mass will be of a dirty colour, and the bottom and parts of the sides fine. “CAULIN.