Marengus — Secrets of Chemical Pallas Revealed, ca. 1700

Sometimes, though rarely, gold grows together in the plain of the earth itself. Ordinarily, however, it is found in the mountains. This is because the forces of the mountainous earth are not exhausted by hoes, rakes, plows, and similar tools that human industry uses. By these tools, the earth of the plain is forced to continually expire and exhale its power. Furthermore, because the substance of mountains is more solid, the celestial heat is better and more strongly contained in them, whereas in the fields it is blown away due to the softness of the earth. Snow also contributes to this, as it is preserved longer upon the mountains. Through antiperistasis the opposition of surrounding qualities, where cold drives heat inward, the heat of the bowels of the earth is stored and strengthened within itself. In the flat plains, on the contrary, this heat is dissolved by the external air. Mountains also abound more in metallic virtue, more so in the depths than in the outer parts. This is because the fatty moisture is consumed by plants, and water flows more freely from the slopes of mountains. In the fields, the abundance of water on the surface hinders the generation of metals. Sterile and very high mountains are all metallic, both because the fatty humor that would produce and nourish plants is consumed within, and because the metallic breaths, being noxious, destroy the plants themselves.

The method of extracting metals from mineral earth

To extract the metals themselves from their ores by art, one must proceed as follows. The stones of the ores are to be pounded in a brass mortar so that they are reduced to a very fine powder. This powder, as is usually done with flour, must be passed through a sieve. Whatever does not pass through the sieve should be pounded again and most perfectly refined until it can be sieved. Then, the sieved powder should be flooded and washed with common water as many times as necessary so that the metallic powder is purged from the earth and other impurities as much as possible. After washing, dry the powder thoroughly at a reverberi reverberatory fire.

When this is done, place the said powder in a mortar or a mill made of marble or stone. Moisten it with water or vinegar

in which sublimatum mercury sublimate, viride gris verdigris, and common salt have been dissolved. Then, place argentum vivum quicksilver over the moistened matter in such a quantity that it covers the entire mass well. Afterward, attach its stone grindstone to the mill. This stone will have an iron handle with which you will turn it in a circle for one or two hours, or more. The more it is turned, the better, because the mercury will attract more of the metallic substance. Then, the mercury should be washed with common water and separated from the earthiness by a sieve. Finally, let the mercury be passed and filtered through a leather bag. It will leave behind in the bottom of the bag whatever metallic substance it attracted. This metallic substance remaining in the leather, when well washed and dried, is melted as is customary and poured into a mold. The said mercury squeezed through the leather must be saved, for it will always serve for this kind of work. This is the method used by miners in the Indijs Indies, referring to Spanish America.

Another method

Other workers, to attract perfect metals from minerals by means of mercury, place one hundred pounds of the above-mentioned washed and dried powders in a large iron vessel. Or they place enough powder so the vessel is half full and no more. They mix in two pounds of well-pulverized Lythargirij auri litharge of gold or yellow lead oxide. Others add two pounds of mercury and pour the water described below over it. They leave four fingers of the vessel empty so that the water does not overflow when agitated. Then they light a fire under the vessel, keeping the water always heated, and continuously mix the matter with an iron spatula. After two hours have passed, they pour off the water and add more. They cook, mix, and pour off as before. They repeat these operations until a certain dead sand remains at the bottom of the vessel. Then they wash that matter with common water. At the bottom of the large vessel, something remains which contains—