D. Deductions. We learn from the foregoing analyses that the metals entering into the composition of the brass of the earliest ages were copper, tin, and lead, although the latter seldom occurs in any considerable quantity, except in the oldest specimens, and in many even of these, particularly in the early Macedonian coins, it is entirely wanting. The iron, cobalt, and nickel, together with traces of sulphur, which sometime occur, are evidently too small in quantity to have been intentionally added to the mixture, and consequently their presence must be rather ascribed to the localities from which the ancients drew their supply of ores, and the imperfect methods employed for their reduction, than to any design on the part of the artists. The cutting instruments which have been examined, are uniformly composed of copper and tin, with the occasional admixture of a small quantity of lead, which was probably added for the purpose of communicating a certain degree of toughness to the alloy, and it is also remarkable that the proportion of tin to that of copper, both in the celts and sword-blades, is very nearly as one to ten. Zinc first makes its appearance a short time previous to the Christian era, and is continued in all the subsequent coins, although occasionally associated with lead and tin, until it almost entirely disappears in the small brass of the period of the Thirty Tyrants, when its place is supplied by a quantity of silver, varying from 0.76 to nearly 8 per cent., and which may perhaps have been intentionally added for the purpose of increasing the value of the metal. In In speaking of these coins, Pinkerton remarks:-"It may be proper to observe, before leaving this part of my subject, that the metal used in the Parts of the Assarion, or in the small brass coins, is, as may be supposed, very little attended to by the ancients. those of the first emperors, yellow brass is sometimes employed, but it is always of a refuse, or bad kind; as in the Semis of Nero, for instance, GENIO AVGVSTI. But copper is the general metal used in parts of the As, from the earliest times down to the latest; and if sometimes brass be employed, it is never such as appears in the Sestertii and Dupondiarii, which is very fine and beautiful; but only the refuse. Yellow brass of the right sort seems to have totally ceased in the Roman coinage, with the Sestertius, under Gallienus; though a few small coins of very bad metal, of that hue appear so late as Julian II."* On referring to the table of analyses, we shall, however, perceive, that although the results obtained seem to confirm the assertions made relative to yellow brass, in the above quotation, yet that in no * Vol. i., 126. VOL. LII. NO. CIII.—JANUARY 1852. one instance, has a coin been found to consist of copper alone; and the only case in which this metal proved to be unalloyed, was in the spear-head, Fig. 4, found in Ireland. The largest proportion of lead occurs in the ancient Roman As, and its parts, in which it was probably employed for the purpose of rendering the alloy of which they consist easily fusible; for these coins being originally cast and not stamped like other money, a metal melting at a low temperature would materially facilitate this operation. The later coins, containing a large proportion of tin, seem to have been struck whilst the metal was still warm, as it would be impossible to obtain such sharp impressions as they usually bear, by the force of any blow applied on a metal so very hard and brittle, at ordinary temperatures. Pinkerton states, that in the Roman mint, the alloy was first cast into the form of bullets, and that these were afterwards flattened and struck by the die, until an impression of sufficient depth was obtained. The appearance of many both of the Greek and Roman coins, indicates that the form of the blank pieces was spherical, but. the metal of these very coins, is frequently so brittle, that they may easily be broken by a blow from the hammer, and could not have received their present form without being previously heated and struck whilst the metal was in a pasty state. That this was the method actually employed, is rendered very probable from some of the devices on the coins themselves, particularly on a Denarius of the Carisia family, bearing on the obverse, the head of Moneta, with name; and on the reverse, the implements used by the Romans in their coinage, viz., two dies, with the hammer and pincers; which is doubtless a correct representation of the apparatus employed in the Roman mint.* From the presence of the pincers in this design, it is almost certain that the metal was struck hot, as the blank could otherwise be more conveniently placed on the die by the hand, than through the intervention of tongs, which would rather embarrass than facilitate the operation. With respect to the furnaces employed by the ancients, little information can be obtained, as these arts were formerly either held as secrets by a few individuals, who made a mystery of their operations, or they were too much despised by ancient authors, to afford them a subject for their writings; and we are consequently more indebted for our scanty knowledge of ancient metallurgy to the vestiges of primitive foundries, which have occasionally been brought to light in various parts of the world, than to any accounts which may have been transmitted to us from those remote times. The first method of smelting ores, doubtless consisted in placing the mineral in heaps, together with several successive layers of wood, which being kindled, first roasted, and then reduced a portion of the *Till on Coins, 7. material with which it was mixed. In Macedonia, where lead mines were worked in the time of Philip, the father of Alexander, large heaps of slag are found so far above the level of the rivers of the country, that the furnaces in which they were produced must have been worked either by bellows moved by human labour, or by the force of the prevailing winds alone.* We are also told, that the Peruvians were in the habit of melting their ores by the simple application of fire, or when they were of a very refractory nature, by means of furnaces so constructed on high ground as to yield a draught without the aid of bellows, a machine with which they were totally unacquainted.† The boles of Derbyshire, many of which from the pigs of Roman lead found in their vicinity, may be presumed to be of great antiquity, were worked in nearly a similar manner, and continued to be thus carried on during several centuries, as this method of smelting was, according to Childrey, not quite extinct in the seventeenth century, who, in speaking of the Peak, says: "The lead-stones in the Peak, lie but just within the ground, next to the upper crust of the earth. They melt the lead on the top of the hills that lie open to the west wind; making their fires to melt it as soon as the west wind begins to blow, which wind, by long experience, they find to hold longest of all others. But for what reason I know not, since I should think lead were the easiest of all metals to melt, they make their fires extraordinary great."‡ Discoveries made by various travellers in Russia, during the last century, throw considerable light on the subject of mining and metallurgy as anciently practised in that part of the world. The remains of numerous mines have been traced by Gmelin, Lepechin and Pallas, on the southern and eastern borders of the Ural Mountains; and in them were found hammers and chisels of copper, as well as various instruments of the same metal, of which the uses are at present unknown. From the absence of any remains of masonry in the neighbourhood, these excavations are inferred to have been made by a nomadic people, probably the Scythians; and from no iron tools having been found in any of them, we may conclude that these operations were carried on before the conquest of Siberia by the Tartars, who effected the subjugation of that part of Asia, about 150 years before our era.§ Sledges made of large stones, to which handles had been attached, were also discovered, together with boars' fangs, with which the gold appears to have been collected, and leathern bags or pockets in which it was preserved. With such imperfect tools, the progress made must necessarily have been exceedingly slow, and in one instance, after reaching a band of rock and * Watson's Chemical Essays, iii., 265. † Alonso Barhu.-Treatise on Metals, French translation, i., 272. § Histoire Généalogique des Tartares. penetrating it for a short distance, the miners seem to have lost patience and abandoned the works. The pits or shafts are well made, about seven feet in diameter, and of a circular form, some of them being 20 fathoms in depth. The passages and props are also well executed, but the former so low and narrow, that they could only have been excavated with the greatest difficulty to the workmen. The ores when extracted were carried to the nearest rivulet for the purpose of being crushed and washed, which operations were probably dispensed with in the richest varieties, which were sometimes melted in the mines themselves, metallic copper, together with slag, and the tools employed in melting and refining, having been found in some of them. Lumps of copper, which contain no traces of gold, have also been discovered, although the copper ores of the districts are found associated with that metal, and it is therefore evident that the ancient people who worked these mines were acquainted with a method of refining gold. The smelting was effected in small furnaces made of red bricks, and of which Gmelin found nearly a thousand in the eastern parts of Siberia. The height and breadth of these were about two feet, and the width three. They were also furnished with holes in two of their opposite sides, the one for the introduction of bellows, and the other for the escape of the metal and slags. In the neighbourhood of the furnaces were found large quantities of broken pottery, together with numerous heaps of scoriæ, which indicate that operations to a very considerable extent, have at some period been carried on in that locality. Gmelin likewise found in the same districts the remains of various furnaces which had been employed for the extraction of silver, and remarked that the lead with which it was associated had been thrown away in the scoriæ, whilst the whole of the silver was carefully extracted. By what means this was effected, in this particular case, is of course impossible for us to say, although it is highly probable that cupellation in some form was resorted to. Diodorus (III. 14) informs us, that gold was purified by being melted and heated in earthen pots, together with an alloy of tin and lead, to which salt and barley-bran were added, and that the fire was kept up during five successive days. Another ancient author* states, that gold was melted by a gentle fire with the addition of salt, nitre, and alum, and that the same process was employed for refining silver. It is, however, difficult to understand what action these substances, with the exception of the nitre, could have on the purification of silver and gold, and we may therefore conclude, that the action of the air was after all the chief means of oxidation employed.† Hippocrates de Diæta, 193. †The nitre of the Ancients was probably carbonate of soda. |