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washed off by the water. When a little quantity is to bepowdered in a mortar, it should likewise be done byblows of the pestle, not by grinding : a blow only flat-tening the metalline particles, while triture wears anddivides them, in part, to such tenuity, as not freely tosubside in water. Stones of the hard flinty kind are pre-viously made red hot, and quenched in water; by whichmeans they are rendered more easily pulverable, and at thefame time many of the small particles of gold, melting inthe fire, unite and form larger masses.

III. Separation of goldfrom earths andftones by mercury.

Where the minuteness of the particles of gold, andthe weight of the matter with which they are intermixed,renders them inseparable by water, quicksilver is called inaid for imbibing and detaining the gold. The gold sands,freed by water, as in the foregoing article, from as muchof the lighter matter, as can be washed off by water with-out endangering a great loss of the gold, are dried, and asmall proportion, less than a hundredth part of theirweight, of mercury poured on them : the whole is wellkneaded up together, that the mercury may penetrate, as.much as possible, into all the interstices between thegrains; it imbibes the atoms of gold it meets with, andthe sand is afterwards washed off by water.

In the Spanish West Indies, at those mines where thegold is bedded in stones, and requires quicksilver forits separation, the stony matter is reduced to as sine pow-der as possible, that every atom of the gold may be laidopen to the mercury. The powder is soaked for sometime in a solution of common salt; the mercury squeezedin through a linen cloth, so as to fall like dew all overthe surface ; and the mixture being well stirred and,

C c kneaded,