The remains at Mt. Laurion show many of the ancient mills and concentration works of the Greeks, but we cannot be absolutely certain at what period in the history of these mines crushing and concentration were introduced. While the mines were worked with [Pg 281]great activity prior to 500 B.C. (see [note 6, p. 27]), it was quite feasible for the ancient miner to have smelted these argentiferous lead ores direct. However, at some period prior to the decadence of the mines in the 3rd Century B.C., there was in use an extensive system of milling and concentration. For the following details we are indebted mostly to Edouard Ardaillon (Les Mines Du Laurion dans l'Antiquité, Chap. IV.). The ore was first hand-picked (in 1869 one portion of these rejects was estimated at 7,000,000 tons) and afterward it was apparently crushed in stone mortars some 16 to 24 inches in diameter, and thence passed to the mills. These mills, which crushed dry, were of the upper and lower millstone order, like the old-fashioned flour mills, and were turned by hand. The stones were capable of adjustment in such a way as to yield different sizes. The sand was sifted and the oversize returned to the mills. From the mills it was taken to washing plants, which consisted essentially of an inclined area, below which a canal, sometimes with riffles, led through a series of basins, ultimately returning the water again to near the head of the area. These washing areas, constructed with great care, were made of stone cemented over smoothly, and were so efficiently done as to remain still intact. In washing, a workman brushed upward the pulp placed on the inclined upper portion of the area, thus concentrating there a considerable proportion of the galena; what escaped had an opportunity to settle in the sequence of basins, somewhat on the order of the buddle. A quotation by Strabo (III, 2, 10) from the lost work of Polybius (200-125 B.C.) also indicates concentration of lead-silver ores in Spain previous to the Christian era: "Polybius speaking of the silver mines of New Carthage, tells us that they are extremely large, distant from the city about 20 stadia, and occupy a circuit of 400 stadia, that there are 40,000 men regularly engaged in them, and that they yield daily to the Roman people (a revenue of) 25,000 drachmae. The rest of the process I pass over, as it is too long, but as for the silver ore collected, he tells us that it is broken up, and sifted through sieves over water; that what remains is to be again broken, and the water having been strained off, it is to be sifted and broken a third time. The dregs which remain after the fifth time are to be melted, and the lead being poured off, the silver is obtained pure. These silver mines still exist; however, they are no longer the property of the state, neither these nor those elsewhere, but are possessed by private individuals. The gold mines, on the contrary, nearly all belong to the state. Both at Castlon and other places there are singular lead mines worked. They contain a small proportion of silver, but not sufficient to pay for the expense of refining." (Hamilton's Translation, Vol. I., p. 222). While Pliny gives considerable information on vein mining and on alluvial washing, the following obscure passage (XXXIII, 21) appears to be the only reference to concentration of ores: "That which is dug out is crushed, washed, roasted, and ground to powder. This powder is called apitascudes, while the silver (lead?) which becomes disengaged in the furnace is called sudor (sweat). That which is ejected from the chimney is called scoria as with other metals. In the case of gold this scoria is crushed and melted again." It is evident enough from these quotations that the Ancients by "washing" and "sifting," grasped the practical effect of differences in specific gravity of the various components of an ore. Such processes are barely mentioned by other mediæval authors, such as Theophilus, Biringuccio, etc., and thus the account in this chapter is the first tangible technical description. Lead mining has been in active progress in Derbyshire since the 13th century, and concentration was done on an inclined board until the 16th century, when William Humphrey (see [below]) introduced the jigging sieve. Some further notes on this industry will be found in [note 1, p. 77]. However, the buddle and strake which appear at that time, are but modest improvements over the board described by Agatharchides in the quotation above.
The ancient crushing appliances, as indicated by the ancient authors and by the Greek and Roman remains scattered over Europe, were hand-mortars and mill-stones of the same order as those with which they ground flour. The stamp-mill, the next advance over grinding in mill-stones, seems to have been invented some time late in the 15th or early in the 16th centuries, but who invented it is unknown. Beckmann (Hist. of Inventions, II, p. 335) says: "In the year 1519 the process of sifting and wet-stamping was established at Joachimsthal by Paul Grommestetter, a native of Schwarz, named on that account the Schwarzer, whom Melzer praises as an ingenious and active washer; and we are told that he had before introduced the same improvements at Schneeberg. Soon after, that is in 1521, a large stamping-work was erected at Joachimsthal, and the process of washing was begun. A considerable saving was thus made, as a great many metallic particles were before left in the washed sand, which was either thrown away or used as mortar for building. In the year 1525, Hans Pörtner employed at Schlackenwalde the [Pg 282]wet method of stamping, whereas before that period the ore there was ground. In the Harz this invention was introduced at Wildenmann by Peter Philip, who was assay-master there soon after the works at the Upper Harz were resumed by Duke Henry the Younger, about the year 1524. This we learn from the papers of Herdan Hacke or Haecke, who was preacher at Wildenmann in 1572."
In view of the great amount of direct and indirect reference to tin mining in Cornwall, covering four centuries prior to Agricola, it would be natural to expect some statement bearing upon the treatment of ore. Curiously enough, while alluvial washing and smelting of the black-tin are often referred to, there is nothing that we have been able to find, prior to Richard Carew's "Survey of Cornwall" (London, 1602, p. 12) which gives any tangible evidence on the technical phases of ore-dressing. In any event, an inspection of charters, tax-rolls, Stannary Court proceedings, etc., prior to that date gives the impression that vein mining was a very minor portion of the source of production. Although Carew's work dates 45 years after Agricola, his description is of interest: "As much almost dooth it exceede credite, that the Tynne, for and in so small quantitie digged up with so great toyle, and passing afterwards thorow the managing of so many hands, ere it comes to sale, should be any way able to acquite the cost: for being once brought above ground in the stone, it is first broken in peeces with hammers; and then carryed, either in waynes, or on horses' backs, to a stamping mill, where three, and in some places sixe great logges of timber, bounde at the ends with yron, and lifted up and downe by a wheele, driven with the water, doe break it smaller. If the stones be over-moyst, they are dried by the fire in an yron cradle or grate. From the stamping mill, it passeth to the crazing mill, which betweene two grinding stones, turned also with a water-wheel, bruseth the same to a find sand; howbeit, of late times they mostly use wet stampers, and so have no need of the crazing mills for their best stuffe, but only for the crust of their tayles. The streame, after it hath forsaken the mill, is made to fall by certayne degrees, one somewhat distant from another; upon each of which, at every discent, lyeth a greene turfe, three or foure foote square, and one foote thick. On this the Tinner layeth a certayne portion of the sandie Tinne, and with his shovel softly tosseth the same to and fro, that, through this stirring, the water which runneth over it may wash away the light earth from the Tinne, which of a heavier substance lyeth fast on the turfe. Having so clensed one portion, he setteth the same aside, and beginneth with another, until his labour take end with his taske. The best of those turfes (for all sorts serve not) are fetched about two miles to the eastwards of S. Michael's Mount, where at low water they cast aside the sand, and dig them up; they are full of rootes of trees, and on some of them nuts have been found, which confirmeth my former assertion of the sea's intrusion. After it is thus washed, they put the remnant into a wooden dish, broad, flat, and round, being about two foote over, and having two handles fastened at the sides, by which they softly shogge the same to and fro in the water betweene their legges, as they sit over it, untill whatsoever of the earthie substance that was yet left be flitted away. Some of later time, with a sleighter invention, and lighter labour, doe cause certayne boyes to stir it up and down with their feete, which worketh the same effect; the residue, after this often clensing, they call Blacke Tynne."
It will be noticed that the "wet stampers" and the buddle—worked with "boyes feete"—are "innovations of late times." And the interesting question arises as to whether Cornwall did not derive the stamp-mill, buddle, and strake, from the Germans. The first adequate detailed description of Cornish appliances is that of Pryce (Mineralogia Cornubiensis, London, 1778) where the apparatus is identical with that described by Agricola 130 years before. The word "stamper" of Cornwall is of German origin, from stampfer, or, as it is often written in old German works, stamper. However, the pursuit of the subject through etymology ends here, for no derivatives in German can be found for buddle, tye, strake, or other collateral terms. The first tangible evidence of German influence is to be found in Carew who, continuing after the above quotation, states: "But sithence I gathered stickes to the building of this poore nest, Sir Francis Godolphin (whose kind helpe hath much advanced this my playing labour) entertained a Dutch Mynerall man, and taking light from his experience, but building thereon farre more profitable conclusions of his owne invention, hath practised a more saving way in these matters, and besides, made Tynne with good profit of that refuse which Tynners rejected as nothing worth." Beyond this quotation we can find no direct evidence of the influence of "Dutch Mynerall men" in Cornish tin mining at this time. There can be no doubt, however, that in copper mining in Cornwall and elsewhere in England, the "Dutch Mynerall men" did play a large part in the latter [Pg 283]part of the 16th Century. Pettus (Fodinæ Regales, London, 1670, p. 20) states that "about the third year of Queen Elizabeth (1561) she by the advice of her Council sent over for some Germans experienced in mines, and being supplied, she, on the tenth of October, in the sixth of her reign, granted the mines of eight counties ... to Houghsetter, a German whose name and family still continue in Cardiganshire." Elizabeth granted large mining rights to various Germans, and the opening paragraphs of two out of several Charters may be quoted in point. This grant is dated 1565, and in part reads: "Elizabeth, by the Grace of God, Queen of England, France, and Ireland, Defender of the Faith, &c. To all Men to whom these Letters Patents shall come, Greeting. Where heretofore we have granted Privileges to Cornelius de Voz, for the Mining and Digging in our Realm of England, for Allom and Copperas, and for divers Ewers of Metals that were to be found in digging for the said Allom and Copperas, incidently and consequently without fraud or guile, as by the same our Privilege may appear. And where we also moved, by credible Report to us made, of one Daniel Houghsetter, a German born, and of his Skill and Knowledge of and in all manner of Mines, of Metals and Minerals, have given and granted Privilege to Thomas Thurland, Clerk, one of our Chaplains, and Master of the Hospital of Savoy, and to the same Daniel, for digging and mining for all manner of Ewers of Gold, Silver, Copper, and Quicksilver, within our Counties of York, Lancaster, Cumberland, Westmorland, Cornwall, Devon, Gloucester, and Worcester, and within our Principality of Wales; and with the same further to deal, as by our said Privilege thereof granted and made to the said Thomas Thurland and Daniel Houghsetter may appear. And we now being minded that the said Commodities, and all other Treasures of the Earth, in all other Places of our Realm of England...." On the same date another grant reads: "Elizabeth, by the Grace of God, Queen of England, France, and Ireland, Defender of the Faith, &c. To all Men to whom these our Letters Patents shall come, Greeting. Where we have received credible Information that our faithful and well-beloved Subject William Humfrey, Saymaster of our Mint within our Tower of London, by his great Endeavour, Labour, and Charge, hath brought into this our Realm of England one Christopher Shutz, an Almain, born at St. Annen Berg, under the Obedience of the Electer of Saxony; a Workman as it is reported, of great Cunning, Knowledge, and Experience, as well in the finding of the Calamin Stone, call'd in Latin, lapis calaminaris, and in the right and proper use and commodity thereof, for the Composition of the mix'd Metal commonly call'd latten, etc." Col. Grant-Francis, in his most valuable collection (Smelting of Copper in the Swansea District, London, 1881) has published a collection of correspondence relating to early mining and smelting operations in Great Britain. And among them (p. 1., etc.) are letters in the years 1583-6 from William Carnsewe and others to Thomas Smyth, with regard to the first smelter erected at Neath, which was based upon copper mines in Cornwall. He mentions "Mr. Weston's (a partner) provydence in bringynge hys Dutch myners hether to aplye such businys in this countrye ys more to be commendyd than his ignorance of our countrymen's actyvytyes in suche matters." The principal "Dutche Mineral Master" referred to was one Ulrick Frosse, who had charge of the mine at Perin Sands in Cornwall, and subsequently of the smelter at Neath. Further on is given (p. 25) a Report by Jochim Gaunse upon the Smelting of copper ores at Keswick in Cumberland in 1581, referred to in [note 2, p. 267]. The Daniel Hochstetter mentioned in the Charter above, together with other German and English gentlemen, formed the "Company of Mines Royal" and among the properties worked were those with which Gaunse's report is concerned. There is in the Record Office, London (Exchequer K.R. Com. Derby 611. Eliz.) the record of an interesting inquisition into Derbyshire methods in which a then recent great improvement was the jigging sieve, the introduction of which was due to William Humphrey (mentioned [above]). It is possible that he learned of it from the German with whom he was associated. Much more evidence of the activity of the Germans in English mining at this period can be adduced.
On the other hand, Cornwall has laid claims to having taught the art of tin mining and metallurgy to the Germans. Matthew Paris, a Benedictine monk, by birth an Englishman, who died in 1259, relates (Historia Major Angliae, London, 1571) that a Cornishman who fled to Germany on account of a murder, first discovered tin there in 1241, and that in consequence the price of tin fell greatly. This statement is recalled with great persistence by many writers on Cornwall. (Camden, Britannia, London, 1586; Borlase, Natural History of Cornwall, Oxford, 1758; Pryce, Mineralogia Cornubiensis, London, 1778, p. 70, and others).
[Pg 295][11] Lapidibus liquescentibus. (See [note 15, p. 380]).
[Pg 297][12] Historical Note on Amalgamation. The recovery of gold by the use of mercury possibly dates from Roman times, but the application of the process to silver does not seem to go back prior to the 16th Century. Quicksilver was well-known to the Greeks, and is described by Theophrastus (105) and others (see [note 58, p. 432], on quicksilver). However, the Greeks made no mention of its use for amalgamation, and, in fact, Dioscorides (V, 70) says "it is kept in vessels of glass, lead, tin or silver; if kept in vessels of any other kind it consumes them and flows away." It was used by them for medicinal purposes. The Romans amalgamated gold with mercury, but whether they took advantage of the principle to recover gold from ores we do not know. Vitruvius (VII, 8) makes the following statement:—"If quicksilver be placed in a vessel and a stone of a hundred pounds' weight be placed on it, it will swim at the top, and will, notwithstanding its weight, be incapable of pressing the liquid so as to break or separate it. If this be taken out, and only a single scruple of gold be put in, that will not swim, but immediately descend to the bottom. This is a proof that the gravity of a body does not depend on its weight, but on its nature. Quicksilver is used for many purposes; without it, neither silver nor brass can be properly gilt. When gold is embroidered on a garment which is worn out and no longer fit for use, the cloth is burnt over the fire in earthen pots; the ashes are thrown into water and quicksilver added to them; this collects all the particles of gold and unites with them. The water is then poured off and the residuum placed in a cloth, which, when squeezed with the hands, suffers the liquid quicksilver to pass through the pores of the cloth, but retains the gold in a mass within it." (Gwilt's Trans., p. 217). Pliny is rather more explicit (XXXIII, 32): "All floats on it (quicksilver) except gold. This it draws into itself, and on that account is the best means of purifying; for, on being repeatedly agitated in earthen pots it casts out the other things and the impurities. These things being rejected, in order that it may give up the gold, it is squeezed in prepared skins, through which, exuding like perspiration, it leaves the gold pure." It may be noted particularly that both these authors state that gold is the only substance that does not float, and, moreover, nowhere do we find any reference to silver combining with mercury, although Beckmann (Hist. of Inventions, Vol. I, p. 14) not only states that the above passage from Pliny refers to silver, but in further error, attributes the origin of silver amalgamation of ores to the Spaniards in the Indies.
The Alchemists of the Middle Ages were well aware that silver would amalgamate with mercury. There is, however, difficulty in any conclusion that it was applied by them to separating silver or gold from ore. The involved gibberish in which most of their utterances was couched, obscures most of their reactions in any event. The School of Geber ([Appendix B]) held that all metals were a compound of "spiritual" mercury and sulphur, and they clearly amalgamated silver with mercury, and separated them by distillation. The Probierbüchlein (1520?) describes a method of recovering silver from the cement used in parting gold and silver, by mixing the cement (silver chlorides) with quicksilver. Agricola nowhere in this work mentions the treatment of silver ores by amalgamation, although he was familiar with Biringuccio (De La Pirotechnia), as he himself mentions in the [Preface]. This work, published at least ten years before De Re Metallica, contains the first comprehensive account of silver amalgamation. There is more than usual interest in the description, because, not only did it precede De Re Metallica, but it is also a specific explanation of the fundamental essentials of the Patio Process long before the date when the Spaniards could possibly have invented that process in Mexico. We quote Mr. A. Dick's translation from Percy (Metallurgy of Silver and Gold, p. 560):
"He was certainly endowed with much useful and ingenious thought who invented the short method of extracting metal from the sweepings produced by those arts which have to do with gold and silver, every substance left in the refuse by smelters, and also the substance from certain ores themselves, without the labour of fusing, but by the sole means and virtue of mercury. To effect this, a large basin is first constructed of stone or timber and walled, into which is fitted a millstone made to turn like that of a mill. Into the hollow of this basin is placed matter containing gold (della materia vra che tiene oro), well ground in a mortar and afterward washed and dried; and, with the above-mentioned [Pg 298]millstone, it is ground while being moistened with vinegar, or water, in which has been dissolved corrosive sublimate (solimato), verdigris (verde rame), and common salt. Over these materials is then put as much mercury as will cover them; they are then stirred for an hour or two, by turning the millstone, either by hand, or horse-power, according to the plan adopted, bearing in mind that the more the mercury and the materials are bruised together by the millstone, the more the mercury may be trusted to have taken up the substance which the materials contain. The mercury, in this condition, can then be separated from the earthy matter by a sieve, or by washing, and thus you will recover the auriferous mercury (el vro mercurio). After this, by driving off the mercury by means of a flask (i.e., by heating in a retort or an alembic), or by passing it through a bag, there will remain, at the bottom, the gold, silver, or copper, or whatever metal was placed in the basin under the millstone to be ground. Having been desirous of knowing this secret, I gave to him who taught it to me a ring with a diamond worth 25 ducats; he also required me to give him the eighth part of any profit I might make by using it. This I wished to tell you, not that you should return the ducats to me for teaching you the secret, but in order that you should esteem it all the more and hold it dear."
In another part of the treatise Biringuccio states that washed (concentrated) ores may be ultimately reduced either by lead or mercury. Concerning these silver concentrates he writes: "Afterward drenching them with vinegar in which has been put green copper (i.e., verdigris); or drenching them with water in which has been dissolved vitriol and green copper...." He next describes how this material should be ground with mercury. The question as to who was the inventor of silver amalgamation will probably never be cleared up. According to Ulloa (Relacion Historica Del Viage a la America Meridional, Madrid, 1748) Dom Pedro Fernandes De Velasco discovered the process in Mexico in 1566. The earliest technical account is that of Father Joseph De Acosta (Historia Natural y Moral de las Indias, Seville, 1590, English trans. Edward Grimston, London, 1604, re-published by the Hakluyt Society, 1880). Acosta was born in 1540, and spent the years 1570 to 1585 in Peru, and 1586 in Mexico. It may be noted that Potosi was discovered in 1545. He states that refining silver with mercury was introduced at Potosi by Pedro Fernandes de Velasco from Mexico in 1571, and states (Grimston's Trans., Vol. I, p. 219): "... They put the powder of the metall into the vessels upon furnaces, whereas they anoint it and mortifie it with brine, putting to every fiftie quintalles of powder five quintalles of salt. And this they do for that the salt separates the earth and filth, to the end the quicksilver may the more easily draw the silver unto it. After, they put quicksilver [Pg 300]into a piece of holland and presse it out upon the metall, which goes forth like a dewe, alwaies turning and stirring the metall, to the end it may be well incorporate. Before the invention of these furnaces of fire, they did often mingle their metall with quicksilver in great troughes, letting it settle some daies, and did then mix it and stirre it againe, until they thought all the quicksilver were well incorporate with the silver, the which continued twentie daies and more, and at least nine daies." Frequent mention of the different methods of silver amalgamation is made by the Spanish writers subsequent to this time, the best account being that of Alonso Barba, a priest. Barba was a native of Lepe, in Andalusia, and followed his calling at various places in Peru from about 1600 to about 1630, and at one time held the Curacy of St. Bernard at Potosi. In 1640 he published at Madrid his Arte de los Metales, etc., in five books. The first two books of this work were translated into English by the Earl of Sandwich, and published in London in 1674, under the title "The First Book of the Art of Metals." This translation is equally wretched with those in French and German, as might be expected from the translators' total lack of technical understanding. Among the methods of silver amalgamation described by Barba is one which, upon later "discovery" at Virginia City, is now known as the "Washoe Process." None of the Spanish writers, so far as we know, make reference to Biringuccio's account, and the question arises whether the Patio Process was an importation from Europe or whether it was re-invented in Mexico. While there is no direct evidence on the point, the presumption is in favour of the former.