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Sala, &c. The Schwartz, in the county of Schwartzburgin upper Saxony, is said to be rich in this metal, and itssands to be worked with great profit: Stahl mentions apiece found in it as broad as a middling bean, though notso thick, and supposes that the 8 al a receives all its goldfrom this river; the gold of the Sala being found onlybelow where the Schwartz enters it, and being less plenti-ful and in smaller grains. It is generally reckoned thatthe gold particles, in all auriferous rivers, are washed outby the stream from some rich beds, and afterwards rest orsettle where the current is languid, or in places wherethey escape its force : from what particular sources thegold in different rivers proceeds, does not seem to havebeen examined.

The richest parts of rivers, within the extent in whichthey roll gold, are those where their course is stow andinterrupted, where they widen or change their direc-tion : the most favourable season is when the water hassubsided after a flood. The appearance of the sand af-fords an useful mark for distinguishing the richestspots ; the gold being always most plentiful where thesand is redd iff or blackish, or of a colour somewhat differ-ent from what is seen elsewhere; not that the red orblack sands have any natural connexion with the gold,but on account of their being more ponderous than thewhite, so that the same cause, which determines the par-ticles of gold, determines these also to subside. Theblack sand abounds with iron, being vigorously attractedby the magnet ; the red, viewed in a microscope, appears,as Reaumur observes, a beautiful congeries of colouredcrystals, imitating all the gems known to the jeweller,among which those of the ruby and hyacinth teints are themost common, whence the reddish colour of the sand tothe naked eye; the particles of gold are of irregular

figures,