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[ 2 6 ] vini probatorius be put in it, and it turns imme diately black, it muft be lead. 77. The ores of lead are commonly gloffy, con- fffting of cubical parts, which are of different fizes, according as they contain more or lefs of fulphur; thofe which have large cubes melt very eafy. Thofe lead-ores which are formed by a calx of lead will melt, after being calcined and ftratified as above with charcoal, and fome addition of faltpetre and tartar. EXPERIMENT XXXVII. 78. Take the calcined ore, add fome butter, fuet, train-oil, or other animal fat fubftance ; calcine it thus a fecond time, flirting it continually; then try whether the magnet or loadftone will attrafl fome particles Of it; in which cafe it is IRON. yg. Or pour on the calcined ore vitriolic acid, let it digeft in a warm place j if a naufeous fmell epfue, with a kind of effervefcence and the whole infufion grow dark-brown or reddifh, or if this folution will flrike an in fufion of gallapples or tea black, it is iron. 80. Or take equal quantities of dry ox-blood and fait of tartar, burn the pounded and mixed fubftances in a crucible, diflolvc the allies in a fufficient quantity of water ; pour fomewhat of this liquor in a diluted folution of an ore fufpe&ed to contain iron; if the watery or diluted folution turns blue, and precipitates a blue powder, the ore thus exa mined contains iron. EX PE-
