The prejudices in America against the use of anthracite were as as they are here ; but there they are now being rapidly dissipated by an irre pressible spirit of enterprise, guided by scientific intelligence ; whilst we, out of reverence to the ignorance of our forefathers, adhere to and cherish them. In America anthracite was at first introduced into the parlour grates, where, having gained a triumph, it descended into the kitchens, in spite of the vehement pro testations of the ministers of the victualling having, however, here demonstrated its superiority over all other kinds of fuel, it next presents itself to the notice of stea-furnace men and the iron masters; these, however, asserted that there was something in its very nature which, in their occupations, forbade its use ; and they were so obdurate, Dr. Jones informs us, that " you might as well have attempted to convince them that it was fit to be made into candles, as that it might be employed for their purposes if their furnaces were suitably constructed, and the fuel properly managed." ' It appears likely, however," our scientific historian continues, " that it will soon assert its claims to superior excellence in these applications also, and triumph over the prejudices of the managers of furnaces, as it has over those of the householder, the cook, and the blacksmith." Improved Blowing Machinery.—In continuing our account of the process of obtaining iron in the smelting furnace, we omitted to notice that the blowing apparatus delineated in connexion therewith, has, in a great measure, been superseded by improved mechanism of that kind. The pumping cylinder, by an arrangement of valves well understood, is made to draw air on both sides of the piston, so that whilst the air enters on one side it is forced out on the other into the regulating vessel, from whence it is usually conducted into the fur nace by two or three distinct pipes and tuyeres. But a most ingenious arrange ment of blowing cylinders was invented by Mr. Paterson, of Lanark, which is described and figured in the article BLOWINO MACHINES, wherein several others are given. Water bellows have been extensively employed, but the objection to these has been the humidity which the air acquired by the spray; to remedy this defect, the air is forced into a dry regulator, which is simply a large air tight metal box, about 10 feet square and 40 feet long. At Bradley iron works they have a regulating cylinder of still greater dimensions. The uniform else deity which the air acquires in these great chambers causes it to issue in a constant equalized blast.
The blowing of heated air has recently been introduced at several foundries, and likewise at the Clyde iron works. It is the invention of Mr. J. B. Neilson, of Glasgow, whose patent was enrolled in March, 1829, and is designated an imroved application of air to produce heat in fires, forges, and furnaces, where bellows or other blowing apparatus is required. He proposes that the air sup plied by any kind of machine shall, before it enters the furnace or cupola, be made to pass through an air-vessel heated to very high temperature, a red heat if possible, by which means a current of hot air will be thrown on the fire instead of the cold current usually employed. It is recommended that the air vessel be surrounded with some non-conducting substance, and imbedded in masonry. The capacity of this vessel for a smith's forge he recommends to be about 1,200 cubic inches, and for a cupola or blast furnace, about 10,000 cubic inches. It was much doubted whether the increased temperature of the fire thus blown would produce advantages equivalent to the expense of constructing the air vessel and keeping it at the requisite heat; and as respects the smelting of iron in particular, the theory seemed opposed to the well-known fact that a much larger quantity of iron is yielded by the blast furnaces in the winter season, or when the air is cold, than during the summer season, when the air is warm. The experiments at the Clyde iron works, have however been reported most favourably of, and the saving of coal attending it is so ;great, that it was stated, in the Glasgow Chronicle, to be calculated to accomplish a saving in the consumption of this island to the amount of 200,0001. annually. At the Clyde iron works the air was heated to 220° Fehr. before it was discharged into the furnace; • an effect which was produced by the expenditure of only one eleventh part of the cost of fuel it takes to heat it to the same temperature in the blast furnace, which may be accounted for by the circumstance that Mr. Neilson's air vessel is heated by coals, while the blast furnace is heated by coke Should further experience in this invention confirm the views of the patentee, it may be regarded as a valuable improvement in metallurgic operations.
Refining Furnace.—The refining of pig-metal is a modern intermediate process of conversion, which the experience of our iron masters has led them to believe is the best economy in the preparation of the metal for being subse quently rendered malleable in the puddling furnace, although it is well understood to be unnecessary to the production of wrought iron. The furnaces employed for this purpose are small buildings, termed refineries ; a vertical section of one of them is given in the cut on the next page. a is a thick cast-iron trough, having three of its sides made double, with a hollow space between, around which water is caused to flow from an external cistern b, the cool ing effect of the fluid serving to prevent the fusion or other injury of the metal sides of the furnace by the intense heat; at c (in a line) are two pipes, through which air is forced from a blowing machine upon the materials in the trough ; these pipes are kept cool by a constant stream of water always flowing over them, brought on by small pipes d, regulated by cocks. The bottom of the furnace is of brick, on which the fuel is laid, and over it the pigs to be refined. The building is sur mounted by a wide chimney about 12 feet high, and the front, which is left open, has a projecting roof to cover the workmen who attend to it. In Wales it is usual to make these furnaces what is termed double; that is, the fire is somewhat larger though single, but the blast is double, there being usually three pipes and tuyeres on each of two opposite sides of the furnace ; each of the pipes are generally about an inch in diameter, and supplied with a blast equal to about 2 or 21 lbs. pressure upon the square inch. The pigs are kept in a state of fusion for some time, exposed to an intense heat from the powerful blast just mentioned, which drives off a portion off the carbon united to the metal. When the operation, which usually occupies two hours, is deemed to be complete, a hole in front of the hearth is tapped, through which the liquid metal flows into a very thick oblong flat mould, of cast-iron, placed over a cistern of water ; this causes the metal to be rapidly chilled, which is thus brought into a cake about 2 feet broad and 20 feet long. This plate of metal is extremely brittle, and presents on its fracture a silvery whiteness : it weighs about a ton. In some refineries the furnace is lined with firebricks or stones, without water running round it, and the refined metal is cast upon sand in shallow moulds or depressions, and water is then thrown upon the metal to cool it quickly. As inattention or neglect on the part of the refiner would be productive of serious loss to the iron master, he is always paid according to the metal produced. Great experience and practical skill are requi site qualities in a refiner; his occupation is one of great personal exertion, and he is exposed to an intense fire, that no one unaccustomed to it could even approach. He puts the charge of pigs upon the fire, attends to the progress of the melting, supplies the fire from time to time with coke, frequently stirring it up to equalize the heat; sees that the tuyeres are in good order, and that the water circulates uninterruptedly ; runs out the metal when it is ready ; he removes the plate from its mould when it has a little cooled, by means of a lever, on to a truck, and wheels it out of his shed ; he then prepares his mould for the next plate, removes his cinders, and repeats the operation. The quantity of refined metal thus produced by a " double" furnace in Wales, is from 60 to 70 tons per week, of 6 days of 24 hours each, the men working in turns of 12 hours at a time, and 12 hours rest. The refiner selects his materials according to the quality of iron wanted. The best quality is from the dark grey pig, or No. 3, and the infe rior sorts from bright, mottled, and white in their order. The very " worst " white iron cannot be used by itself in the refinery ; being almost infusible from its deficiency of carbon, it is disposed to clog and settle on the hearth. To work up such iron in the refinery, it is mixed with pigs of a "better quality," or those containing more carbon, the union conferring fusibility. When . No. 3 pigs are used, it requires about 221 cwt. of them to produce one ton of refined metal ; the "yield" however varies, from causes before adverted to, according to the degree of carbonation of the pig metal employed, the quality of the coke, the management of the blast, and various other circumstances. This reduction of weight is however not an entire loss, as a quantity of " cinder" is produced which floats on the top of the metal, and detaches itself as it cools; this cinder contains usually about 50 per cent, of its weight of iron, which is recoverable on the blast furnace.