These three rich tin-bearing areas were: (1) Galicia in north-western Spain, (2) the south of Brittany, especially between the estuaries of the Loire and the Vilaine, a deposit long since exhausted, and (3) the still-important deposits of southern England, in Cornwall and parts of Devon, which are believed to have been visited by the Phœnicians. Just as the gold of California brought population and civilisation to the Far West of North America long before the natural increase of eastern peoples would have led to a westward movement, so the rich tin deposits of south-western Britain, with the other metals of those favoured islands, brought merchants and navigators to what was the Far West of ancient Europe.
The bold navigators who had learnt their craft in the Mediterranean Sea left its basin by the Strait of Gibraltar, and visited successively those masses of ancient rocks which project out into the ocean, and form the western extremities of Spain, France and Britain. But it was not only the sea route which was utilised, at least in later times. Perhaps so long ago as five centuries before our era a land route was organised which carried British tin to Marseilles, and thus to the Mediterranean. The great valley of the Rhone renders such a traverse of France feasible, and the passage from the valley to the Rhone to that of the Loire or of the Seine is easy. The existence of a commerce in tin thus ensured that France was early and deeply permeated by Mediterranean civilisation, for it involved the existence of high roads through her land, at a time when northern Europe generally was cut off from the civilisation of the Mediterranean. There is even reason to believe that trade in tin led to the founding of an early maritime power on the barren shores of Brittany. The trade in tin certainly did much to open the way for the future civilisation of France.
Though, as we have indicated, bronze was for long of relatively great importance, yet the use of iron dates back to great antiquity. It seems to have been a rare and precious metal when the Homeric poems took shape, and for long afterwards its use was partial and limited. The fact, however, that it is very readily destroyed by rust when exposed to air and damp, makes it difficult to draw any certain conclusions from its absence in ancient remains.
The slow growth of the use of iron must be largely ascribed to the great difficulties in smelting it, especially when it occurs in impure forms. Iron does not occur in the pure state, as copper does to a small extent, but it is enormously abundant, being found, to a greater or less extent, in almost all rocks. Relatively pure ores are rare, most iron-bearing minerals containing a large number of impurities, some of which are very difficult to remove. Further, the process of smelting always requires much fuel, and, in the case of the more impure ores, remarkable skill and science. The result was that the early smiths could only employ a very high grade of ore; all others were useless to them. Even with a high grade of ore, they could only extract a relatively small amount of the iron present.
A very curious little proof of this latter fact is furnished by the Roman iron workings in the Forest of Dean in Gloucestershire. The refuse thrown out of the ancient furnaces worked by the Romans here, was re-smelted by the British smiths long centuries afterwards, and this refuse fed their furnaces for a period of between two and three hundred years.
The next point of interest in regard to iron is the source of the necessary fuel. At first wood or charcoal was always employed, and therefore iron could only be smelted in the vicinity of forests. Thus the Forest of Dean, already mentioned, supplied the wood used by the Romans in smelting, and the trees of the Weald or “wood” of Sussex and Kent were completely removed during the long centuries when the iron ores of that region were smelted. The Forest of Arden, near Birmingham, is another region where iron was long smelted by the aid of charcoal. The amount of fuel required, especially in the early days, was very great, and as the forests were cleared without any regard for scientific forestry, it naturally followed that in many districts the destruction of the necessary fuel led to a diminution of the industry.
In England coal was not generally employed in the smelting of iron until after the middle of the eighteenth century, and long before that the British forests had been largely destroyed. The result was that the British iron industry had declined, and in the early part of that century considerably more iron was imported than was made in England. The countries which at this time were specially favoured in connection with the industry were those in which pure iron ores co-existed with extensive forests. This condition occurred especially in Germany, where the iron deposits formerly worked were those of the upland regions which have kept their forests till this day. Thus the wood and the ores of the Harz Mountains and of the Erzgebirge, or Iron Mountains, were of great importance before the industrial revolution, and up till the early part of the eighteenth century the German iron industry was more important than the British.
The replacement of charcoal by coal led to a great diminution of the cost of production, and permitted the use of low-grade ores, but it was not in itself a great improvement. Charcoal is a singularly pure form of carbon, and its use as the reducing agent gives a high quality of iron. Coal, on the other hand, often contains impurities which spoil the iron, and have to be provided against in various ways. Not all coal, indeed, is suitable for iron smelting. The result is that where charcoal can still be obtained cheaply, as in the Scandinavian countries and in parts of Russia, it is still used in smelting, and the iron so produced is particularly valuable.
The original demand for iron, as we have seen, was very small, and even down to the middle of the eighteenth century remained insignificant. But with the use of machinery, the spread of railways, the replacement of wood by iron in shipbuilding and for the framework of buildings, etc., the demand in all civilised communities has become enormous, has become too great to permit of any forests supplying the necessary fuel. With the far increased demand has come an elaboration of methods which means very costly installations and much skill and training among the workers.
From the time of the industrial revolution till the present, then, a well-developed iron industry has demanded the following:—fuel, usually furnished by coal; an abundant supply of the ore, either furnished locally or easily obtained by water carriage, ores being so bulky that land carriage is rarely profitable; certain accessories, notedly limestone to serve as a flux, and ganister, a kind of sandstone used to form a lining in parts of the apparatus used; capital, necessary for the purchase and fitting up of the costly plant; the tradition and skill which come from the long practice of the industry.