Take two or four grains (if you have no greater quantity) of any ore that you have, and put it to half an ounce of Venice glass. Melt them together in a crucible (the crucible being covered) and according to the tincture that the glass receives from the ore, so may you judge what kind of metal there is in the ore. For if it be a copper ore, then the glass will be tinged with a sea-green colon
If copper and iron, a grass-green.
If iron, a dark yellow.
If tin, a pale yellow.
If silver, a whitish yellow.
If gold, a fine sky colon
If gold and silver together, a smaragdine colon
If gold, silver, copper, and iron together, an amethyst colon
A PRETTY OBSERVATION UPON THE MELTING OF COPPER AND TIN TOGETHER
First, make two bullets of red copper of the same magnitude. Make also two bullets of the purest tin in the same mold as the others were made. Weigh all four bullets and observe the weight well. Then melt the copper bullets first. Upon their being melted, put the two tin bullets and melt them together, but have a care that the tin fume not away. Then cast this molten mixture in the same molds as before, and it will scarce make three bullets, but yet they weigh as heavy as the four did before they were melted together.
I suppose the copper condenses the body of the tin which before was very porous, and which condensation rather adds than diminishes the weight thereof.
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