294 PHILOSOPHICAL TRANSACTIONS. [anNO 166Q. 



seen in glass-houses: and then they receive a gentle calcination, mixing with 

 them ingredients suitable to the peccant humour, if I may so speak, of the ore. 

 As if, for example, the metal be sulphureous and antimonial, rust and dross of 

 iron is found to be very proper : if martial, and abounding in iron, then sulphur 

 and antimony reduced to powder is used to good purpose. Sulphur has a par- 

 ticular force to soften and dissolve iron. The ore being ground, calcined, and 

 nicely sifted, they divide it in several heaps, and then, by lesser essays, they find 

 out how much silver is contained in every heap ; where it is very common to 

 find only 6 ounces in 100 pounds, sometimes 12, but if it yield 18, it is es- 

 teemed a very rich vein ; yet sometimes there are found great masses all of pure 

 silver, called Virgin metal. Having discovered the quantity of silver in each 

 heap, they proportionably besprinkle them with quicksilver at several times, 

 stirring the ore about, to mix the mass well together. I find they have only 

 conjectural signs to know when the mercury has entirely performed its office in 

 separating all the silver from the heterogeneal substances. When by the colour 

 of the mercury, coagulated by the silver in clear massy lumps, they conjecture 

 the work done, they wash it by means of three vessels, standing in order one 

 under the other, so that the matter in the first and highest vessel being washed 

 and stirred about, all the dust of the heterogeneous minerals, that do not in- 

 corporate with the mercury, is carried away with the water into the other 

 vessels, and from thence quite thrown out by the continual current of the 

 water; in the mean while, the silver in clotted lumps, called pellas, is by the 

 weight of the mercury depressed downi to the bottom of the tubs or vessels. 



The mercury with the silver is taken out of the vessels, and diligently 

 squeezed in coarse and strong linen, and even beaten with a beetle, by which 

 the quicksilver is separated, as much as may be, from the silver. And this 

 mass is afterwards reduced, in moulds of the shape of the Indian pine- apple, into 

 a pyramidal or conical figure, which they call Pineas de plata, and thus fashioned 

 for the easier placing them round about the ridges of a large earthen vessel, like 

 a blind alembic ; about the top of which, a fire being made, all the rest of 

 the mercury abandons the silver, and falls to the bottom. The silver is melted 

 down with the liga, as it is called, which the king of Spain allows, by which he 

 returns to the people in copper that fifth part which they allow him of all the 

 silver. 



To conclude, to give you some of my thoughts concerning the so much 

 discoursed of transmutation of metals ; concerning which I am of opinion, that 

 that change is erroneously apprehended by many, imagining that the whole 

 imperfect metal is totally transformed into the more perfect, by the substance 

 mixed with it; whereas the mixture added to the melted metal, joins itself, as 



