“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 dissolved clay into another vessel. Let it settle, pour off the water, and dry it. I will 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 burn 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 process for melting the stone before described. If the stone is burned to purity, the Caulin will be as white as snow; if but partially 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.