Musaeum metallicum

silver, and they disagree. This appears most manifest in furnaces while white lead tin is liquefied, for it floats on silver and is easily extracted with iron rods.

On the other hand, metals and living creatures differ with the greatest contrariety, because they scatter certain exhalations hostile to the animal spirit; for this reason, it is nowhere read that any animal was nourished by metals. Indeed, where metallic veins are found, there neither plants grow nor do living creatures dwell; and in confirmation of this, we understand that in metal mines the legs of workers are often vitiated, which are later healed in the stone quarries of Assos lapis Assius. For this cause, Physicians order pharmacists not to use metals in preparing pearls or other medicines of this kind, but only marble stones, since there is a danger that some metallic residue might adhere to the medicines being prepared, which would be diametrically opposed to human nature, and from which grave symptoms could emerge. Pliny adds this as a crowning point to this treatise, that the odors emanating from metal mines are indeed unpleasant to all animals, but are of the greatest detriment especially to dogs, which exhale from the metals of silver.
Lib. 33. c. 6. Odor of metals harmful to dogs.

THE METHOD OF PREPARING METALS.

Instruments for metallurgy.

Working men, in the first place, as Agricola reports, must find wedges, plates, hammers, rods, poles, winches, mattocks, and shovels; for these instruments are most necessary for extracting metallic veins. A mine, however, must be situated in a mountainous place, not remote from any river, spring, or brook, so that the material from the pit can be conveniently washed before smelting. And since veins of metals are enclosed between the cracks of rocks, miners sometimes thrust iron rods into the cracks and strike down the vein; but when veins run through the sides of rocks, they use hammers, and when such instruments are used in vain, then they remove the rocks by the violence of fire to extract the veins. But metallurgists must first make a trial of the discovered vein to see whether it contains a little or a great quantity of metal, for when work is done at a loss, the vein is to be abandoned. The experiment is made from the smelting of a small quantity; hence it is known whether the smelting of a large quantity will bring detriment or profit. Smelting, therefore, seems necessary in many ways, not only so that metals may be prepared for use, but also so that they may be separated from one another; for they are mostly mixed, and their faults are corrected. For Ovid sang that fire is the principal instrument suitable for this, in this manner:
Book 4 of Fasti.

All things are purified by devouring fire, and it
smelts away the flaw of the metal.

First, therefore, the working men throw fragments of the veins into chests, so that they may be pounded by pestles set upon them, driven by a water wheel, for they always provide huge streams of water brought down from the mountains, which drive the large circles of the wheels with rapid speed. But the thicker stones with which metals are mixed are reduced by hammers at first sight, washed in pools, and again sifted, so that finally they may be ground; and by all these means, the metallic material is prepared before it is smelted in furnaces. There are many furnaces in a metal workshop in which veins are liquefied and silver is separated from bronze, while huge bellows are lifted by a water wheel, and by constant blowing and motion, they excite the flame in the furnaces with a great roar. Then the working men throw in the metals from above, and others draw out the fused metal, separated from the crushed stones, with large ladles and pour it into molds. But not only in this way is precious metal separated from vile, and conversely vile from precious; for often two metals are found in one and the same vein, since naturally some portion of gold is found mixed with silver and bronze, a small portion of silver in black lead lead and iron, some part of black lead in silver, and finally some portion of iron in bronze. Gold, however, is mostly separated from silver by "strong water" aqua fortis/nitric acid prepared from vitriol, or alum, and saltpeter, which is most excellent for separating silver from gold.