“Secondly, with respect to the manner of applying the earth and stones:--They are to be ground into powder, and laid on the ware as potters use their own composition. With respect to the sorts of earths and stones which are adapted to the purposes they are various. The toad-stone of Derbyshire, and other places, the Scotch and Guernsey pebbles, the basaltes, and other productions generally esteemed volcanic, rag stone, slate, shale, granite, gypsum, fluor spar, mare stone, and many other kinds of earths and stones which I know not how to denominate, will all, either severally or when mixed in different proportions with each other, or with siliceous or argillaceous, micaceous, or calcareous earths or stones, or with all of them, answer the purpose. I would have it also understood, that portions of the metallic substances now used for the purpose of glazing earthenware or saline bodies (tho’ not necessary for producing the effect) may be used in conjunction with the earths and stones here mentioned. I would further remark, that the slags of furnaces, the slags of pit-coal, and the crust which forms on the bottom slip-kilns, by themselves, or in conjunction with the substances before mentioned, will glaze earthenware. But as the same effect may be produced by a great many different sorts of earths and stones, when used either separately or when combined in very different proportions, all of which it is impossible to enumerate or ascertain, I think it fit to mention the three following, which have succeeded well with me. Take of Derbyshire toad-stone five parts by weight, fluor spar one part, take thirty-three parts of clay, nineteen parts of flint, thirty-eight parts of striated gypsum, take fluor spar one, two, three or four parts, porcelain clay two parts, siliceous earth one fourth of a part, of calcareous earth one sixth of a part.”