Heroes of the Telegraph [45]
shown by both manufacturers. In England the process is now generally known as the 'Siemens-Martin,' and on the Continent as the 'Martin-Siemens' process.
The regenerative furnace is the greatest single invention of Charles William Siemens. Owing to the large demand for steel for engineering operations, both at home and abroad, it proved exceedingly remunerative. Extensive works for the application of the process were erected at Landore, where Siemens prosecuted his experiments on the subject with unfailing ardour, and, among other things, succeeded in making a basic brick for the lining of his furnaces which withstood the intense heat fairly well.
The process in detail consists in freeing the bath of melted pig-iron from excess of carbon by adding broken lumps of pure hematite or magnetite iron ore. This causes a violent boiling, which is kept up until the metal becomes soft enough, when it is allowed to stand to let the metal clear from the slag which floats in scum upon the top. The separation of the slag and iron is facilitated by throwing in some lime from time to time. Spiegel, or specular iron, is then added; about 1 per cent. more than in the scrap process. From 20 to 24 cwt. of ore are used in a 5-ton charge, and about half the metal is reduced and turned into steel, so that the yield in ingots is from 1 to 2 per cent. more than the weight of pig and spiegel iron in the charge. The consumption of coal is rather larger than in the scrap process, and is from 14 to 15 cwt. per ton of steel. The two processes of Siemens and Martin are often combined, both scrap and ore being used in the same charge, the latter being valuable as a tempering material.
At present there are several large works engaged in manufacturing the Siemens-Martin steel in England, namely, the Landore, the Parkhead Forge, those of the Steel Company of Scotland, of Messrs. Vickers & Co., Sheffield, and others. These produced no less than 340,000 tons of steel during the year 1881, and two years later the total output had risen to half a million tons. In 1876 the British Admiralty built two iron-clads, the Mercury and Iris, of Siemens-Martin steel, and the experiment proved so satisfactory, that this material only is now used in the Royal dockyards for the construction of hulls and boilers. Moreover, the use of it is gradually extending in the mercantile marine. Contemporaneous with his development of the open-hearth process, William Siemens introduced the rotary furnace for producing wrought-iron direct from the ore without the need of puddling.
The fervent heat of the Siemens furnace led the inventor to devise a novel means of measuring high temperatures, which illustrates the value of a broad scientific training to the inventor, and the happy manner in which William Siemens, above all others, turned his varied knowledge to account, and brought the facts and resources of one science to bear upon another. As early as 1860, while engaged in testing the conductor of the Malta to Alexandria telegraph cable, then in course of manufacture, he was struck by the increase of resistance in metallic wires occasioned by a rise of temperature, and the following year he devised a thermometer based on the fact which he exhibited before the British Association at Manchester. Mathiessen and others have since enunciated the law according to which this rise of resistance varies with rise of temperature; and Siemens has further perfected his apparatus, and applied it as a pyrometer to the measurement of furnace fires. It forms in reality an electric thermometer, which will indicate the temperature of an inaccessible spot. A coil of platinum or platinum-alloy wire is enclosed in a suitable fire-proof case and put into the furnace of which the temperature is wanted. Connecting wires, properly protected, lend from the coil to a differential voltameter, so that, by means of the current from a battery circulating in the system, the electric resistance of the coil in the furnace can be determined at any moment. Since this resistance depends on the
The regenerative furnace is the greatest single invention of Charles William Siemens. Owing to the large demand for steel for engineering operations, both at home and abroad, it proved exceedingly remunerative. Extensive works for the application of the process were erected at Landore, where Siemens prosecuted his experiments on the subject with unfailing ardour, and, among other things, succeeded in making a basic brick for the lining of his furnaces which withstood the intense heat fairly well.
The process in detail consists in freeing the bath of melted pig-iron from excess of carbon by adding broken lumps of pure hematite or magnetite iron ore. This causes a violent boiling, which is kept up until the metal becomes soft enough, when it is allowed to stand to let the metal clear from the slag which floats in scum upon the top. The separation of the slag and iron is facilitated by throwing in some lime from time to time. Spiegel, or specular iron, is then added; about 1 per cent. more than in the scrap process. From 20 to 24 cwt. of ore are used in a 5-ton charge, and about half the metal is reduced and turned into steel, so that the yield in ingots is from 1 to 2 per cent. more than the weight of pig and spiegel iron in the charge. The consumption of coal is rather larger than in the scrap process, and is from 14 to 15 cwt. per ton of steel. The two processes of Siemens and Martin are often combined, both scrap and ore being used in the same charge, the latter being valuable as a tempering material.
At present there are several large works engaged in manufacturing the Siemens-Martin steel in England, namely, the Landore, the Parkhead Forge, those of the Steel Company of Scotland, of Messrs. Vickers & Co., Sheffield, and others. These produced no less than 340,000 tons of steel during the year 1881, and two years later the total output had risen to half a million tons. In 1876 the British Admiralty built two iron-clads, the Mercury and Iris, of Siemens-Martin steel, and the experiment proved so satisfactory, that this material only is now used in the Royal dockyards for the construction of hulls and boilers. Moreover, the use of it is gradually extending in the mercantile marine. Contemporaneous with his development of the open-hearth process, William Siemens introduced the rotary furnace for producing wrought-iron direct from the ore without the need of puddling.
The fervent heat of the Siemens furnace led the inventor to devise a novel means of measuring high temperatures, which illustrates the value of a broad scientific training to the inventor, and the happy manner in which William Siemens, above all others, turned his varied knowledge to account, and brought the facts and resources of one science to bear upon another. As early as 1860, while engaged in testing the conductor of the Malta to Alexandria telegraph cable, then in course of manufacture, he was struck by the increase of resistance in metallic wires occasioned by a rise of temperature, and the following year he devised a thermometer based on the fact which he exhibited before the British Association at Manchester. Mathiessen and others have since enunciated the law according to which this rise of resistance varies with rise of temperature; and Siemens has further perfected his apparatus, and applied it as a pyrometer to the measurement of furnace fires. It forms in reality an electric thermometer, which will indicate the temperature of an inaccessible spot. A coil of platinum or platinum-alloy wire is enclosed in a suitable fire-proof case and put into the furnace of which the temperature is wanted. Connecting wires, properly protected, lend from the coil to a differential voltameter, so that, by means of the current from a battery circulating in the system, the electric resistance of the coil in the furnace can be determined at any moment. Since this resistance depends on the