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it was reddish ; on that particularly, which had lost con-siderably of its beauty in the process, the bone ash wastinged of a fine flesh colour. This glass had been preparedfrom twenty-four parts of green glass, four of borax, andone of the powder separated by agitation from an amal-gam of copper.

III. Glajses prepared with saline additions.

All the glasses that could be changed into porcelainwere such as had been brought to their vitreous state bymeans of saline bodies; though some of this class resistedthe operation, and in those which did become porcelain,there were considerable differences, in regard both to thefacility of the change, and the quality of the porcelainitself.

Green glass bottles, composed of sand and the salineashes of wood, answered much the best; and the Frenchbottles better, in point of colour, than the English. Oneof our common quart bottles, and a French quart bottle,being surrounded with the same sand, and baked in thesame fire, for the fame length of time, the porcelain fromthe French bottle turned out, in several repetitions of theexperiment, manifestly the whitest, tho’ in other respectsno material difference was observed. It is probable thatthe difference in colour proceeded from the French glassbeing made with a whiter sand than the English : it issaid that the sand used for green glass in France retains itswhiteness, in great measure, after strong calcination;while that of our glass-houses burns reddish.

The vials, in which Hungary water is brought fromFrance, are very difficultly converted into porcelain, andthe porcelain they afford is less white and less compactthan that of the common bottles. The vials are muchmore fusible than the bottles, probably from their having a

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