[ *7 ] experiment XXXVIII. $i. Infuse in a glafs the calcined ore,with a fu? ludon of potafhes or fait of tartar, mixed to gether with that of quicklime, and let it ftand in a moderately warm place; if the ore be comes on its outfide covered with a fine Iky- blue colour, it undoubtedly contains copper. 82. Infufe the calcined and pounded ore with acid of nitre, put it in a temperate place for digeftion, dilute the folution in a great deal of water, and gradually add fome fpirits of hartfhorn, or volatile alkali; if this ftrikes the diluted folution blue, the ore will yield COPPER, EXPERIMENT XXXIX. 83. Infuse the calcined ore with vitriolic acid, dilute the folution with water; if it precipitate a white powder, and -afterwards yield by eva poration and cryftaftization red cryftals, the ore contains cobalt. 84. Wifmuth and Cobalt are commonly joined in their ores; the firlt native, the lecond mineralized with arfenic and fulphur. The calcination expels the fulphur and the arfenic, both being volatile; the calxes of wifmuth and cobalt remain in the earthy or ftony remnant. The vitriolic acid diflolves both* but if the folution be diluted with water, the calx of wifmuth is precipitated; and the reft, being evaporated, yields the vitriolum fobalti, which has red cryftals. Thus wif muth and cobalt-ores may be tried both at 9nce. EX PE-