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sometimes been previoufly concealed in the crucible, orin the materials, or at the end of the rod, with whichthe matter was stirred in fusion, and sometimes intro-duced into the crucible by a confederate, when the fur-nace was covered, through an aperture communicatingwith another apartment. So many frauds and j uggling ar-tifices are known to have been practised on this occasion,that the evidence of a spectator can be of no force ; andperhaps those, who were more than spectators, were toomuch interested to be admitted as evidences.

I am very far, however, from censuring as impostors2II those who have declared themselves convinced, fromtheir own experiments, of the tranfmutability of basemetals into gold. Many experiments have been alledged,in which base metals were made to yield some portionof gold, and in which gold, treated with certain addi-tions, received an increase : though the quantity ob-tained was rarely such as to bear the charges of the pro-cess, it is reckoned sufficient at least, in a philosophicview, to demonstrate the actual transmutation, into gold,of a substance which before was not gold. Most of theseexperiments are free from suspicion of any fraudulent de-sign ; but there are strong reasons to suspect that theauthors have been themselves deceived by fallacious ap-pearances.

Gold, as we have already seen, is now known to befar more frequent in metals and other minerals, than itwas formerly supposed to be ; and there is little wonder,if men of warm imaginations, biassed by a favourite hy-pothesis, have been led to believe that they producedgold when they extracted it from materials in which itwas not imagined to præexist. We have seen also, in aforegoing section of this essay, that the common methodof parting silver from gold by aqua fortis does not com-

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