s 1*9 ]

os the metal they contain, or os extracting it to advan-tage in the large way. Becher indeed undertook to obtain,gold with profit from the common sea sands, and enteredinto engagements with the states of Holland for establish-ing a mineral work on this foundation : but though expe-riments made on little quantities promised very consider-able gain, and though one trial in large is likewise saidto have proved successful, yet, as he communicated thewhole process to the commissioners appointed to examinethe affair, and as he has shewn that such a work mightbe carried on more advantageously in Holland than in otherparts of Europe, its never having been prosecuted in Hol-land affords a strong presumption of its not being suffi-ciently lucrative. The existence of gold in sands is never-theless an interesting fact, at least to the philosopher, andfurther examination may perhaps find means of making itturn to account.

Though gold has been but lately dhoovered, or expected,in these minerals, in which it is so common and so plen-tiful, their unpromising appearance having given little en-couragement to examine them ; there are others, whoseflattering colour has raised great expectations, but whichhave not been found upon experiment to yield any gold.The yellow pyritæ or marcalites, and other minerals of agolden colour, or containing gold-coloured specks, haveby some been regarded as ores or matrices of gold, andaccordingly submitted to different operations, as fruitlessas expensive : their losing their colour in the fire, orchanging it to a yellow, soon discovers that their tingingmatter is not gold, but sulphur or a ferrugineous calx.There are indeed pyritæ which contain gold, and in quan-tity sufficient to deserve notice: Henckel, in the 12thchapter of his pyritologia, gives an account of some assaysof minerals of this kind brought from the Hungarian

mines,