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and extinction repeated four times or ostener. The colourchanges, from yellow, red, or black, to a reddish brown;In the first and second heating, the sand yields a flightsmell, somewhat like that of garlick, a mark of its con-taining arsenic : at the third time, the arsenical smell isscarcely to be perceived, but on throwing into the cruciblea little tallow, or other like inflammable matter, it becomesstronger than before : this remarkable circumstance is byno means peculiar to these sands, for there are several ar-senical minerals which give out little of their arsenic inthe fire till some inflammable matter is added. The sand,thus calcined, is mixed with twice its weight of granu-lated lead, and equal its weight of black flux, the mixtureput into a crucible, and covered with some sea salt driedover the fire till it has ceased to crackle. The crucible isplaced in a good blast'furnace, the fire strongly excited,and the matter stirred from time to time with an iron rod *the fire must be urged till the scoria flows thin as water jwhich is known by the rod coming out almost clean,without the least knob sticking to the end of it. Thecrucible is then. suffered to cool, and broken for gettingout its contents : on the top is the common salt, in adistinct cake; under this, a shining black, compact, vitre-ous scoria ; and at the bottom, a lump of lead, easily sepa-rable from the scoria. The gold, contained in the sand,is now transferred into the lead, and may be separated byworking off the lead upon a cupel or test. These sands-contain also silver, which here accompanies the gold, andwhich may be parted, after the cupellation, either by aqucvfortis or aqua regia, according as one or the other metalappears to prevail in the mixt. This is the process fol-lowed by M. Lieberecht in the a flays already given an,account off

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