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be made at a very cheap rate, as the glass maker can formvessels more expeditioufly than the potter, and as it ishappily the very coarsest green glass that fields the finestporcelain : Th-at it is easily distinguished from all theother sorts of porcelain by the texture which it exhibitson breaking, as it has nothing of the granulated appear-ance of the other porcelains and earthen wares, any morethan the glossy smoothness of glass and enamels, the sur-face of the fracture being composed of fine fibres likesilken threads : That in beauty it is inferiour to the Chi-nese, but equal to many sorts that are held in esteem;that in utility, and every essential quality of porcelain, itis equal to the best, and that in some respects it is supe-riour to all that have hitherto been made : That it suffersno injury from being suddenly heated or cooled, bearsa vehement fire without melting or altering its figure,and hence, besides its use for ornamental vases, promises tomake excellent vessels for the chemist.

The character given of this porcelain by Reaumur,and the valuable qualities he ascribes to it, rendered it anobject of more importance than it had appeared at first,and engaged me in a further examination of it. Thatthe enquiry might be carried on with some regularity, itwas divided into five heads, (i.) To trace the gradual pro-gress of the change from the state of glass to that ofperfect porcelain, and to discover whether a continuance ofthe process would be productive of any further changes.(2.) To determine the qualities of this kind of porcelain,and how it differs from other porcelains and from glass,in those properties which regard the application of it tocommon uses. (3.) To compare the effects of differentcementing materials on the fame glass, and (4.) the effectsof the fame materials on different kinds of glass. (5.) Toascertain, as far as might be, the cause of the change, or5 the