26 ANNUAL OF SCIENTIFIC DISCOVERT. 



IMPROVEMENT IN THE MANUFACTURE OF IRON. 



The following are extracts from a recent patent by David Stew- 

 art, of Kittaning, Penn., as published in the ♦' Scientific Ameri- 

 can " : — 



'• My invention consists in an improved method of treating iron 

 as it comes from the blast furnace, or remelted pig iron, to remove 

 therefrom the carbon, silica, sulphur, phosphorus, and other im- 

 purities which are found in the iron, and which are not removed 

 from or have been contracted by the iron by the process of re- 

 duction from the ore. 



*' It is well known that pig iron, or iron from the blast furnace, 

 contains a large amount of carbon, which it receives in the process 

 of reduction, and which must be more or less completely removed 

 in order to produce wrought iron or steel. Carbon has a great 

 affinity for oxygen, greater than either carbon or oxygen have for 

 iron, and as the union of carbon and oxygen, at a sufficient tem- 

 perature to produce combustion, evolves a great amount of heat, 

 it follows that by mixing oxygen with molten pig iron, the carbon 

 ignites with vivid combustion, and is thereby eliminated, while 

 the increase of lieat thereby obtained renders the iron more fluid, 

 and obviates the necessity of using other fuel or fire than is fur- 

 nished by the carbon contained in the molten iron. 



*• The most improved mode of accomplishing this object, here- 

 tofore introduced into practice, is to pour the melted metal from 

 the blast furnace into a receiver or vessel through which a stream 

 of atmospheric air is forced at suflScient pressure. This, known 

 as the pneumatic process, is attended with the use of very expen- 

 sive apparatus and machinery, and, moreover, requires to be 

 closely watched, as the operation, if continued too long, injures 

 the metal ; besides, it is not effectual in removing the impurities 

 other than carbon, such as silicon, sulphur, phosphorus, etc. ; and 

 even as respects the removal of the carbon, its operation is not 

 always satisfactory, as it is difficult to secure the equal action of 

 the oxygen on all the particles of iron in the receiver. My im- 

 provement produces a much more satisfactory result, with little or 

 no special apparatus, and produces immediately from the molten 

 jDig metal wrought iron, which may be at once taken to the rolls 

 and worked in like manner as iron which has been puddled and 

 squeezed. 



'♦ My improvement consists in subjecting molten pig metal or 

 iron direct from the blast furnace to the action of oxygen (in any 

 convenient shape, as atmospheric air, ozone, or other vapor or 

 gas containing oxygen), by passing the molten metal in a stream 

 or shower, either poured or forced upwards or sideways, so as to 

 secure an intimate admixture of the particles of iron with the 

 oxygen, or otlier oxygen-bearing gas or vapor. In order to carry 

 this into effect, no special apparatus is required ; indeed, each 

 manufacturer will probably vary the arrangement of his furnace 

 to suit the mode of accompljjshing the desired result which 



