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bottoms of the bottles, were found fully changed through-out. In those pieces which were slowly affected by aweak heat, and those which were more hastily acted uponby a moderately strong one, the progress of the changeitself was, for the most part, nearly in the same manner.

The green glass became first of a bluish colour on thesurface, and in this state, when held between the eyeand the light, it appeared less transparent than before,and of a yellowish hue. After this it was found changeda little way on both sides into a white substance, exter-nally still bluish ; and as this change advanced furtherand further within the glass, the vitreous part in the mid-dle approached more and more to yellow : the white coatwas of a fine fibrous texture, and the fibres disposed, nearlyparallel to one another, not longitudinally as might be ex-pected from the direction given to the parts of the glassin blowing it into vessels, but crosswise to the thicknessof the piece. By degrees, the glass became throughoutwhite and fibrous, the external bluifhnefs at the same timegoing off, and being succeeded by a dull whitish or duncolour : the fibres were for the most part regularly anduninterruptedly arranged from each side to the middle,where the fibres from the two sides, meeting together,formed a kind of partition : along this juncture, there werein some pieces considerable cavities here and there j otherswere perfectly solid.

The pieces which were continued in the fire for anyconsiderable time beyond this period, and those whichwere afterwards returned to it along with fresh sand, suf-fered a fresh change, which proceeded, like the first, fromthe surface to the center. The fibres became dividedor cut into grains at the outer ends, and by degrees theywere thus successively divided through their whole length ;the whole internal part of the porcelain assuming a gra-nulated