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The gold, thus collected into a part of the silver, maybe further concentrated into a smaller part, by granulatingthe mass, and repeating the whole process. The opera-tion may be again and again repeated, till so much of thesilver is separated, that the remainder may be parted byaqua fortis without too much expence.

The foregoing process, according to Schlutter, is prac-tised at Rammelsberg in the lower Hartz. The prevail-ing metal in the ore of Rammelsberg is lead : the quan-tity of lead is at most forty pounds on a quintal or hundredpounds of the ore : the lead, worked off on a test orconcave hearth, yields about a hundred and ten grainsof silver, and the silver contains only a three hundred andeighty fourth part of gold : yet this little quantity of gold,amounting scarcely to a third of a grain in a hundredpounds of the ore, is thus collected with profit. Theauthor above mentioned confines this method of separationto such silver as is poor in gold, and reckons parting withaqua fortis more advantageous where the gold amounts toabove a sixty fourth of the silver : he advises also notto attempt concentrating the gold too far, as a portion of itwill always be taken up again by the silver. Mr. Schefferhowever relates, that he has by this method brought thegold almost to perfect fineness, and that he has likewisecollected all the gold which the silver contained ; thesilver of the last operations, which had taken up a por-tion of the gold, being reserved to be worked over againwith a fresh quantity of gold-holding silver. The sulphu-rated silver is purified by continuing it in fusion for sometime, with a large surface exposed to the air; the sulphurgradually exhales, and leaves the silver entire : the particu-lar method of managing this operation will be given here-after in the history of silver.

Mr.