MECHANICS AND USEFUL ARTS. 91 



one, which removes the oxygen gas and all other impurities, with the 

 presence of atmospheric air. Being thus prepared, the ore melts and 

 descends to the hearth, where it first comes in contact with the fire, 

 which destroys the rest of the pulverized coal by frequent stirring, and 

 the iron is thus partially formed. From this hearth it is thrown to 

 another about eight inches lower down, where it is worked into balls 

 of about one hundred pounds amid the same sheet of fire, and in a few 

 minutes the balls are withdrawn, and placed under the hammer to 

 shape them. Scientific American, Jan. 26. 



MR. PLANT, a well-known practical miner, has invented an improve- 

 ni?nt in the manufacture of iron, which, although it lies in a small 

 compass, is, nevertheless, to all appearances, based on scientific prin- 

 ciples, the main feature of the invention being the application of steam, 

 conjointly with hot or cold blast, into the puddling and preparatory 

 chambers of the puddling-furnace, and by these means the heat in the 

 pucldling-chamber is regulated. London Mining Journal, Jan. 26. 



IMPROVED METHOD OF PRODUCING IRON AND STEEL. 



F. C. KNOWLKS has patented a process for the production of 

 iron and steel directly from the ore. For the first process, that of 

 making the iron directly from the ore, without any previous smelting, 

 he selects those ores most free from earthy matter, and the nearer 

 they approach to pure oxides the better. For the other process of 

 preparing iron ores by cementation in retorts, to make cast-iron by 

 smelting afterwards, the ores are taken indifferently, excepting such 

 as contain much sulphur and arsenic. They are first broken into pieces 

 of moderate size, so as when placed together in a heap there may be 

 interstices between them, capable of admitting a gas or vapor through 

 them without obstruction. They are then placed in retorts, rendered 

 gas-tight, and brought up to a red heat, each of which is connected 

 with gas-tubes, having stopcocks for the purpose of injecting and 

 regulating a current of gas among the ore. For this purpose two 

 sorts of gases are used, common carburetted hydrogen and carbonic 

 oxide prepared by slow combustion of charcoal or coke, though any 

 economical hydro-carbon may be used. When the retorts are charged 

 and the gas generated, the rationale of the process is as follows. The 

 ore being mainly an oxide of iron, the hydrogen of the hydro-carbon 

 unites with the oxygen of the ore to form water, while the carbon 

 unites with another portion of oxygen, forming carbonic oxide or car- 

 bonic acid, as the case may be, leaving metallic iron as the result. 

 The next process, when malleable iron is the proposed product, is to 

 shut off the gas on both sides of the retorts, and transfer their contents 

 to the puddling-furnaces, where the iron is treated in the common 

 way. It may be cut, piled, re-heated, and rolled as usual. If steel be 

 required, the cementation must be carried further, until the reduced 

 metal has absorbed about 1 per cent, of carbon. The reduced and 

 cemented ore is then put into crucibles to be run down into ingots, in 

 wind-furnaces, as is now done in the making of cast-steel. If the 

 earthy matter in the ore require it, some proper flux is to be added 



