There is yet another important alloy, which from its chief use takes the name of bell-metal; its companion alloy is gun-metal. In the mixing of these metals special alloys are aimed at according to the object in view, that is to say, the ingredients vary, but, broadly defined, the copper and its alloy tin used in bell-metal are in the proportion of three to one. The metal was in the past used for those much employed articles of commercial and domestic use, mortars, in addition to the founding of bells. Bell-metal was also the material of which weights and measures (especially the standards kept in many of the old cities) were chiefly made (see illustrations and references thereto in Chapters [X] and [XI]).
The Sources from which Copper is Derived.
Copper seems to have been very widely distributed all over the world, a fact that has contributed to its general use. At one time a local metal employed in a pure state and in conjunction with alloys, chiefly where it was mined, it is now brought to the metal-founder from other parts of the world. Although vast quantities of copper are now imported into England, it was from British mines that the supply was drawn in days gone by. The Britons understood its use, no doubt finding it out by accident, just as the natives of many other countries have done. Copper, as evidenced by the marvellous Benin bronzes, was known in Central Africa long ago. The mines at Mansfield, in Germany, are the oldest in Europe, and there workers have been digging up copper for seven centuries.
The collector of old metal objects naturally takes the greater interest in well authenticated specimens known to have been fashioned in districts once famous for their copper mines. Unfortunately, the Cornish mines produce little ore now. When the Romans worked them they obtained copper quite near to the surface; but such easily mined ores have long been cleared.
Copper smelting was carried on in Cumberland and Northumberland in days gone by. In the seventeenth and eighteenth centuries copper was smelted in Yorkshire and Lancashire. Then we read of the reopening of old Cornish mines and of furnaces being erected in Bristol. The mines of Anglesea are less known, although they were once very active. South Wales has for many years past been closely identified with copper smelting, and rolling mills were established in Swansea as early as 1720; and although the better knowledge of metallic chemistry enables manufacturers to produce copper more economically than in days gone by, the old principle of crushing, calcining, roasting, and washing the ore, although improved by modern machinery, is still adhered to.
As with many other industries, the invention of the steam-engine was a boon to the owners of copper mines in Cornwall, many being flooded towards the end of the eighteenth century. With the steam-engine to work them, pumps were put in operation, mines were cleared, and for a time at any rate ore was procured and renewed activity was visible in many British centres. In those days many of the things we now regard as curios were being made. As with many other raw materials the value of copper steadily advanced, for as trade and commerce grew, immense quantities were used up for sheathing ships' bottoms, roofing buildings, for engravers' plates, and for the rolls used in the printing of calicoes. Other sources of supply have been found, for the chain extending from Land's End to Dartmoor no longer serves. The famous Parys Mines are no more, and it is from foreign countries the supply comes. Some of our Colonies have proved rich in ores, such, for instance, as South Australia, where it is said an early settler examining the burrow of a wombat found the green mineral, that incident leading to the opening of mines yielding vast quantities of copper ore.
The Making of Brass.
The brass of commerce, rolled in sheets, drawn in rods and wire, and cast in ingots ready for the founder, is, as it has been stated, a composite metal, very well suited to many purposes. During the sixteenth century much progress was made in metal-founding. The Worshipful Company of Founders was busy. Many "battery" works were set up in England, and there brass was hammered or battered into shape. Thus brass-workers were engaged in making useful pots and pans, now in their much worn state eagerly sought after by the collector. Some worked with the ladle and crucible, others with the hammer and anvil or wood block.
The earlier brass was composed of copper mixed with calamine melted in a crucible, a process which continued until the more modern form of melting metallic zinc with copper was understood. Champion's process, by which this newer method was carried out, was kept secret for some time, but about the middle of the eighteenth century it was generally understood and the process of stamping brass became a common one in the Birmingham district.