Inventions in the Century

by William Henry Doolittle

With the invention of coke came also the revival of cast iron.

The process of making cast steel was reinvented in England by Benjamin Huntsman of Attercliff, near Sheffield, about 1740. Between that time and 1770 he practised melting small pieces of “blistered” steel (iron bars which had been carbonised by smelting in charcoal) in closed clay crucibles.

In 1784 Henry Cort of England introduced the puddling process and grooved rolls. Puddling had been invented, but not successfully used before. The term “puddling” originated in the covering of the hearth of stones at the bottom of the furnace with clay, which was made plastic by mixing the clay in a puddle of water; and on which hearth the ore when melted is received. When in this melted condition Cort and others found that the metal was greatly improved by stirring it with a long iron bar called a “rabble,” and which was introduced through an opening in the furnace. This stirring admitted air to the mass and the oxygen consumed and expelled the carbon, silicon, and other impurities. The process was subsequently aided by the introduction of pig iron broken into pieces and mixed with hammer-slag, cinder, and ore. The mass is stirred from side to side of the furnace until it comes to a boiling point, when the stirring is increased in quickness and violence until a pasty round mass is collected by the puddler. As showing the value of Cort’s discovery and the hard experience inventors sometimes have, Fairbairn states that Cort “expended a fortune of upward of £20,000 in perfecting his invention for puddling iron and rolling it into bars and plates; that he was robbed of the fruits of his discoveries by the villainy of officials in a high department of the government; and that he was ultimately left to starve by the apathy and selfishness of an ungrateful country. His inventions conferred an amount of wealth on the country equivalent to £600,000,000, and have given employment to 600,000 of the working population of our land for the last three or four generations.” This process of puddling lasted for about an hour and a half and entailed extremely severe labour on the workman.

The invention of mechanical puddlers, hereinafter referred to, consisting chiefly of rotating furnaces, were among the beneficent developments of the nineteenth century.

Prior to Cort’s time the plastic lump or ball of metal taken from the furnace was generally beaten by hammers, but Cort’s grooved rollers pressed out the mass into sheets.

The improvements of the steam engine by Watt greatly extended the manufacture of iron toward the close of the 18th century, as powerful air blasts were obtained by the use of such engines in place of the blowers worked by man, the horse, or the ox.

So far as the art of refining the precious metals is concerned, as well as copper, tin and iron, it had not, previous to this century, proceeded much beyond the methods described in the most ancient writings; and these included the refining in furnaces, pots, and covered crucibles, and alloying, or the mixture and fusion with other metals. Furnaces to hold the crucibles, and made of iron cylinders lined with fire brick, whereby the crucibles were subjected to greater heat, were also known.

The amalgamating process was also known to the ancients, and Vitruvius (B. C. 27) and Pliny (A. D. 79), describe how mercury was used for separating gold from its impurities. Its use at gold and silver mines was renewed extensively in the sixteenth century.

Thus we find that the eighteenth century closed with the knowledge of the smelting furnaces of various kinds, of coke as a fuel in place of charcoal, of furious air blasts driven by steam and other power, of cast iron and cast steel, and of refining, amalgamating, and compounding processes.

Looking back, now, from the threshold of the nineteenth century over the path we have thus traced, it will be seen that what had been accomplished in metallurgy was the result of the use of ready means tested by prolonged trials, of experiments more or less lucky in fields in which men were groping, of inventions without the knowledge of the real properties of the materials with which inventors were working or of the unvarying laws which govern their operations. They had accomplished much, but it was the work mainly of empirics. The art preceding the nineteenth century compared with what followed is the difference between experience simply, and experience when combined with hard thinking, which is thus stated by Herschel: “Art is the application of knowledge to a practical end. If the knowledge be merely accumulated experience the art is empirical; but if it is experience reasoned upon and brought under general principles it assumes a higher character and becomes a scientific art.”