ABSTRACT
The historian of iron and steel is fortunate in that first the trade itself and later the government took a keen interest in the size and structure of the industry, so that statistical data relating to domestic production, as well as imports and exports, are available from the early eighteenth century. The usual basis of output estimates, indeed the only series which can be used for long-run comparisons, was the tonnage of pig iron produced in the blast furnace each year, even though pig was (and is) an intermediate good whose only use is as the raw material for subsequent reworking. In the early eighteenth century about 90 per cent of pig produced in Britain was refined into a tough, malleable, decarburized material known (from its shape) as bar iron. The proportion of pig used for castings gradually rose, as forge technology stagnated while foundry technique improved, until at the beginning of the nineteenth century almost half the output of pig went into castings. Forging was then transformed and by 1830 pig output was distributed in proportions of roughly 70:30 between bar and cast iron, as it had been half a century earlier. After 1856, and more especially 1870, the industry was revolutionized once again as mild steel, essentially an alloy of iron, carbon and small quantities of other elements, became the main end-product of the industry. Paradoxically it was only in 1881, when its decline was already evident, that statistics of puddling forge output began to be collected.
