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require so much caution, in nealing and heating them, asthe common ones: it appears however from Scheffer’saccount, that they are less durable than those made of theashes of bones, though greatly superiour to those of woodashes. Vegetable ashes, which stand pretty well the test-ing of silver, can scarcely bear any great quantity of gold,this metal requiring a considerably stronger fire than theother : but bone ashes answer so effectually, and are amongus so easily procurable, that it is not needful for the re-finer to search for any other materials; though those whowork off large quantities of lead, in order to gain a littlesilver or gold contained in it, may possibly, in places re-mote from populous cities, avail themselves of substancessimilar to the spath above mentioned.

The test, for its greater security, is kept fixed in themould in which it was formed; which is sometimes ashallow vessel made of crucible earth or cast iron, morecommonly an iron hoop, with three bars arched down-wards across the bottom, about two inches deep, and ofdifferent widths, from three or four inches to fifteen ormore, according to the quantity of metal to be tested atonce. The ashes or earthy powder, moistened as formaking cupels, are pressed down in the mould so as tocompletely fill it or rife a little above the sides ; with careto make the mass equally solid, and to put in at once, orat least after the bottom has been pressed close, as muchof the matter as will be sufficient for the whole, for anyadditional quantity will not unite thoroughly with the rest,but be apt to part from it in the fire. The edges arepared smooth, and a portion cut out from the middle witha bent knife, so as to leave a proper cavity, which issmoothed by strewing some dry powder on the surface,and rolling on it a wooden or rather a glass ball.

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