Inventions in the Century

by William Henry Doolittle

Early Spain produced a furnace which was adopted by the whole of Europe as fast as it became known. It was the Catalan furnace, so named from the province of Catalonia, where it probably first originated, and it is still so known and extensively used. “It consists of a four-sided cavity or hearth, which is always placed within a building and separated from the main wall thereof by a thinner interior wall, which in part constitutes one side of the furnace. The blast pipe comes through the wall, and enters the fire through a flue which slants downward. The bottom is formed of a refractory stone, which is renewable. The furnace has no chimneys. The blast is produced by means of a fall of water usually from 22 to 27 feet high, through a rectangular tube, into a rectangular cistern below, to whose upper part the blast pipe is connected, the water escaping through a pipe below. This apparatus is exterior to the building, and is said to afford a continuous blast of great regularity; the air, when it passes into the furnace, is, however, saturated with moisture.”—Knight.

No doubt in such a heat was formed the metal from which was shaped the armour of Don Quixote and his prototypes.

Bell in his history of Metallurgy tells us that the manufacture of malleable iron must have fallen into decadence in England, especially before the reign of Elizabeth and Charles I., as no furnaces equal even to the Catalan had for a long time been in use; and the architectural iron column found in ancient Delhi, 16 inches in diameter, about 48 feet long and calculated to weigh about 17 tons, could not have been formed by any means known in England in the sixteenth century. This decadence was in part due to the severe laws enacted against the destruction of forests, and most of the iron was then brought to England from Germany and other countries.

From time immemorial the manufacture of iron and steel has been followed in Germany, and that country yet retains pre-eminence in this art both as to mechanical and chemical processes. It was in the eighteenth century that the celebrated Freiberg Mining Academy was founded, the oldest of all existing mining schools; and based on developing mining and metallurgy on scientific lines, it has stood always on the battle line in the fight of progress.

The early smelting furnaces of Germany resembled the Catalan, and were called the “Stückofen,” and in Sweden were known as the “Osmund.” In these very pure iron was made.

The art of making cast iron, which differs from the ordinary smelted iron in the fact that it is melted and then run into moulds, although known among the ancients more than forty centuries ago, as shown by the castings of bronze and brass described by their writers and recovered from their ruins, appears to have been forgotten long before the darkness of the middle ages gathered. There is no record of its practice from the time the elder Pliny described its former use (40-79 A. D.), to the sixteenth century. It is stated that then the lost art was re-invented by Ralph Page and Peter Baude of England in 1543—who in that year made cast-iron in Sussex.

The “Stückofen” furnace above referred to was succeeded in Germany by higher ones called the “Flossofen,” and these were followed by still higher and larger ones called “Blauofen,” so that by the middle of the eighteenth century the furnaces were very capacious, the blast was good, and it had been learned how to supply the furnaces with ore, coal and lime-stone broken into small fragments. The lime was added as a flux, and acted to unite with itself the sand, clay and other impurities to form a slag or scoria. The melted purified iron falling to the bottom was drawn off through a hole tapped in the furnace, and the molten metal ran into channels in a bed of sand called the “Sow and pigs.” Hence the name, “pig iron.”

The smelting of ore by charcoal in those places where carried on extensively required the use of a vast amount of wood, and denuded the surrounding lands of forests. So great was this loss felt that it gave rise to the prohibitory laws and the decadence in England of the manufacture of iron, already alluded to. This turned the attention of iron smelters to coal as a substitute. Patents were granted in England for its use to several unsuccessful inventors. Finally in 1619 Dud Dudley, a graduate of Oxford University, and to whom succeeded his father’s iron furnaces in Worcestershire, obtained a patent and succeeded in producing several tons of iron per week by the use of the pitcoal in a small blast furnace.

This success inflamed the wood owners and the charcoal burners and they destroyed Dudley’s works. He met with other disasters common to worthy inventors and discontinued his efforts to improve the art.

It is said that in 1664 Sir John Winter of England made coke by burning sea coal in closed pots. But this was not followed up, and the use of charcoal and the destruction of the forests went on until 1735, when Abraham Darby of the Coalbrookdale Iron Works at Shropshire, England, commenced to treat the soft pit coal in the same way as wood is treated in producing charcoal. He proposed to burn the coal in a smouldering fire, to expel the sulphur and other impurities existing in the form of phosphorus, hydrogen and oxygen, etc. while saving the carbon. The attempt was successful, and thus coke was made. It was found cheaper and superior to either coal or charcoal, and produced a quicker fire and a greater heat. This was a wonderful discovery, and was preserved as a trade secret for a long time. It was referred to as a curiosity in the Philosophical Transactions in 1747. In fact it was not introduced in America until a century later, when in 1841 the soft coal abounding around Pittsburgh in Pennsylvania and in the neighbouring regions of Ohio was thus treated. Even its use then was experimental, and did not become a practical art in the United States until about 1860.