| [76] | Relations des Jésuites, vol. iii. 1666 et 1667. |
| [77] | Henry’s Travels and Adventures, New York, 1809, p. 194. |
CHAPTER IX.
ALLOYS.
THE AGE OF BRONZE—AN INTERMEDIATE COPPER AGE—EUROPEAN COPPER IMPLEMENTS—NATIVE SILVER AND COPPER—TIN AND COPPER ORES—THE CASSITERIDES—ANCIENT SOURCES OF TIN—ARTS OF YUCATAN—ALLOYED COPPER AXE-BLADES—BRONZE SILVER-MINING TOOL—PERUVIAN BRONZES—PRIMITIVE MINING TOOLS—NATIVE METALLURGIC PROCESSES—METALLIC TREASURES OF THE INCAS—TRACES OF AN OLDER RACE—PERUVIAN HISTORY—THE TOLTECS AND MEXICANS—ADJUSTMENT OF CALENDAR—BARBARIAN EXCESSES—NATIVE GOLDSMITH’S WORK—PANAMA GOLD RELICS—MEXICAN METALLIC CURRENCY—EXPERIMENTAL PROCESSES—ANCIENT EUROPEAN BRONZES—TESTS OF CIVILISATION—ANCIENT AMERICAN BRONZES—THE NATIVE METALLURGIST.
The age of bronze in the archæological history of European civilisation symbolises a transitional stage of very partial development, and imperfect materials and arts, through which the Old World passed in its progress towards the maturity of true historic times; but the Bronze Period of the New World is the highest stage of its self-developed civilisation, prior to the intrusion of European arts. Whether we regard the bronze implements of Britain and the North of Europe as concomitant with the intrusion of new races, or only as proofs of the discovery or introduction of a new art pregnant with many civilising and elevating tendencies, they constitute an important element in primitive ethnology. For a time they necessarily coincide with many monuments and works of art pertaining in character to the stone-period; just as the stone implements and weapons still manufactured by the Indians and Esquimaux are contemporaneous with many products of foreign metallurgy, but nevertheless are the perpetuation of processes developed in a period when metallurgic arts were entirely unknown. The evidence that the British Bronze Period followed a simpler and ruder one of stone is such as scarcely to admit of challenge, independent of the à priori likelihood in favour of this order of succession. The question however suggests itself whether metallurgy did not find its natural beginning there, as elsewhere, in the easy working of the virgin copper, and so intercalate a copper age between Europe’s stone, and its true Bronze Period. On this subject Dr. Latham remarks, in his Ethnology of the British Islands, “Copper is a metal of which, in its unalloyed state, no relics have been found in England. Stone and bone first; then bronze, or copper and tin combined; but no copper alone. I cannot get over this hiatus; cannot imagine a metallurgic industry beginning with the use of alloys.” It is a mistake, however, to say that no unalloyed British copper relics have been found. No very special attention was directed till recently to the distinction. Nearly all the earlier writers who refer to the metallic weapons and tools of ancient Mexico and Central America, apply the term “copper” to the mixed metal of which these were made; while among European antiquaries the corresponding relics of the Old World are no less invariably designated bronze, though in many cases thus taking for granted what analysis can alone determine. It is an error, however, that the later nomenclature of archæological periods has tended to strengthen: partly from the lack of appreciation of the importance of the argument in favour of the first use of the metals in a condition corresponding to the most primitive arts, and the discovery of scientific processes at later stages.
This peculiar interest attaches to the metallurgy of the New World, that there all the earlier stages are clearly defined: the pure native metal, wrought by the hammer without the aid of fire; the melted and moulded copper; the alloyed bronze; and then the smelting, soldering, graving, and other processes resulting from accumulating experience and matured skill. But examples of British implements of pure copper have also been noted. In a valuable paper by Mr. J. A. Phillips, on the metals and alloys known to the ancients,[[78]] the results of analyses of thirty-seven ancient bronzes are given. Among these are included three swords, one from the Thames, the others from Ireland; a spear-head, two celts, and two axe-heads: all of types well-known among the weapons of the “Bronze Period.” Yet of the eight articles thus selected as examples of “bronze” weapons, one, the spear-head, proved on analysis to be of impure but unalloyed copper. Its composition is given as copper, 99·71; sulphur, ·28. In 1822, Sir David Brewster described a large battle-axe of pure copper, found at a depth of twenty feet in Ratho Bog, near Edinburgh, under circumstances scarcely less remarkable than some of the discoveries of works of art in the drift. The workmen dug down through nine feet of moss and seven feet of sand, before they came to the hard black till-clay; and at a depth of four feet in the clay the axe was found. The author accordingly remarks: “It must have been deposited along with the blue clay prior to the formation of the superincumbent stratum of sand, and must have existed before the diluvial operations by which that stratum was formed. This opinion of its antiquity is strongly confirmed by the peculiarity of its shape, and the nature of its composition.”[[79]] In 1850, my brother, Dr. George Wilson, undertook a series of analyses of ancient British bronzes for me, and out of seven specimens selected for experiment, one Scottish axe-head, rudely cast, apparently in sand, was of nearly pure copper.[[80]] Of eight specimens of metal implements selected for me by Mr. Thomas Ewbank, of New York, as examples of Peruvian bronze; four of them, on analysis, proved to be of unalloyed copper. The rich collections of the Royal Irish Academy furnish interesting confirmation of this idea of a transitional copper era. Dr. Wilde remarks, in his Catalogue of Antiquities, “Upon careful examination, it has been found that thirty of the rudest, and apparently the very oldest celts, are of red, almost unalloyed copper.” In addition to those there are also two battle-axes, a sword-blade, a trumpet, several fibulæ, and some rudely formed tools, all of copper; and now that attention has been directed to the subject, further examples of the same class will doubtless accumulate.
A very important difference, however, distinguishes the mineral resources of the British and the North American copper regions. Copper, as we have seen, occurs in the trappean rocks of Keweenaw and Ontonagon, in masses of many tons weight; and detached blocks of various sizes lie scattered about in the superficial soil or exposed along the lake shore, ready for use without any preparatory skill, or the slightest knowledge of metallurgy. Nature in her own vast crucibles had carried the metal ores through all their preparatory stages, and left them there for man to shape into such forms as his convenience or simplest wants suggested. The native silver had undergone the like preparation, and is of frequent occurrence as a perfectly pure metal, being found, even when interspersed in the mass of copper, still in distinct crystals, entirely free from alloy with it. But neither tin nor zinc occurs throughout the whole northern region to suggest to the native metallurgist the production of that valuable alloy which is indissolubly associated with the civilisation of Europe’s Bronze age. In Britain it is altogether different. The tin and copper lie together, ready for alloy, but both occur in the state of impure ores, inviting and necessitating the development of metallurgy before they can be turned to economic uses. Tin is obtained in Cornwall almost entirely from its peroxide; and copper occurs there chiefly combined with sulphur and iron, forming the double sulphuret which is commonly called copper pyrites or yellow copper ore. The smelting process to which it has to be subjected is a laborious and complicated one; and if we are prepared to believe in the civilisation of Britain’s Bronze Period as a thing of native growth, the early discovery and use of alloys very slightly affects the question.
The ancient American miner of Lake Superior never learned to subject his wealth of copper to the action of fire, and transfer it from the crucible to the shapely mould. No such process was needed where it abounded in inexhaustible quantities in a pure metallic state. If, in the midst of such readily available metallic resources, he was found to have used tools of bronze or brass, to have transported the tin or zinc of other regions to his furnaces, and to have laboriously converted the whole into a preferable substitute for the simpler metal that lay ready for his use, it would be difficult indeed to conceive of such as the initial stage in his metallurgy industry. But Britain presents no analogy to this in its development of metallurgy arts. Tin, one of the least widely-diffused of metals, is found there in the greatest abundance, and easily accessible, not as a pure metal, but as an ore which is readily reduced by charcoal and a moderate degree of heat to that condition. This was the metallic wealth for which Britain was sought by the ancient traders of Massilia, and the fleets of the Mediterranean; and on it we may therefore assume her primitive metallurgists to have first tried their simple arts. But alongside of it, and even in natural combination with it, as in tin pyrites and the double sulphuret, lies the copper, also in the condition of an ore, and requiring the application of the metallurgist’s skill before it can be turned to account. We know that at the very dawn of history tin was exported from Britain. Copper also appears to have been wrought, from very early times, in North Wales as well as in Cornwall. Both metals were found rarely, and in small quantities, in the native state, but these may have sufficed to suggest the next step of supplying them in larger quantities from the ores. To seek in some unknown foreign source for the origin of metallurgic arts, which had there all the requisite elements for evoking them, seems wholly gratuitous; and, if once the native metallurgist learned to smelt the tin and copper ores, and so had been necessitated to subject them to preparatory processes of fire, the next stage in progressive metallurgy, the use of alloys, was a simple one. It might further be assumed that, with the discovery of the valuable results arising from the admixture of tin with copper, the few pure copper implements—excepting where already deposited among sepulchral offerings,—would for the most part be returned to the melting-pot, and reproduced in the more perfect and useful condition of the bronze alloy. There seems, however, greater probability in the supposition that if Britain had a copper period, or age of unalloyed metals, it was of brief duration.
The cassiteron, or tin which made the British Islands famous among Phœnician and Greek mariners, long before the Roman legions ventured to cross the narrow seas, was derived, as has been noted, from the same south-western peninsula, where copper is still wrought. The name of Cassiterides, or Tin Islands, bestowed on Cornwall and the adjacent isles, seems to imply that tin was the chief export, and was transported to the Mediterranean, to be mixed with the copper of the Wady Maghara, and other Asiatic mines, to form the Egyptian, Phœnician, and Assyrian bronze. Tin, therefore, the easiest of all metals to subject to the requisite processes, first engaged the skill of the British metallurgist; and that mastered, the proximity of the copper ore in the same mineral districts, inevitably suggests all the subsequent processes of smelting, fusion, and alloy.
The practical value of the alloy of copper and tin was well-known both to the Phœnicians and the Egyptians. Tin occurs in considerable abundance, and in the purest state, in the peninsula of Malacca, and thence, probably, it was first brought to give a new impetus to early eastern civilisation. Britain is its next and its most abundant source; and since America was embraced within the world’s sisterhood of nations, Chili and Mexico have become known as productive sources of the same useful metal. But the mineral wealth of Mexico and Peru was familiar to nations of the New World long before it was made to contribute to European commerce; and to a proximity of the metals best suited for the first stages of human progress, corresponding in some degree to that to which Britain’s ancient metallurgy has been traced, the curious phases of a native and purely aboriginal civilisation may be ascribed, which revealed itself to the wondering gaze of the first European adventurers who followed in the steps of Columbus. Whatever doubts may arise relative to the native origin of British metallurgy, and the works of art of the European Bronze Period, in consequence of their most characteristic illustrations being preserved in the mixed metal, bronze, and not in pure copper: there is no room for any such doubts relative to the primitive metallurgy of the New World. The American continent appears to have had its two entirely independent centres of self-originated metallurgic arts: its greatly prolonged but slight progressive Copper Period; and apart from this, and in part at least contemporaneous with it, a separate Bronze Period, with its distinct centres of more advanced civilisation and better regulated metallurgic industry, in which the value of metallic alloys was practically understood.