242 THE SCIENTIFIC PAPERS OF 



metallic iron are set free, and taking the atomic weights of 

 iron = 28, and of silicon 22'5, it follows that for every 4 x 22 - 5 = 

 90'0 grains of silicon abstracted from the metal, 9x28 = 252 

 grains of metallic iron are liberated from the cinder. 



Carbonic oxide, again, being represented by C 0, and the cinder 

 by Fe 3 O 4 , it follows that for every four atoms of carbon removed 

 from the metal, three atoms of iron are liberated ; and taking into 

 account the atomic weights of carbon = G and of iron = 28, it 

 follows that for every G x 4 = 24 grains of carbon oxidized, 

 28 x 8 = 84 grains of metallic iron are added to the bath. 



Assuming ordinary forge pig, after being remelted in the 

 puddling furnace, to contain about 3 per cent, of carbon and 

 2 per cent, of silicon, it follows from the foregoing that in 

 removing this silicon 'W 3 x 2 = 5'6 per cent., and in removing 

 the carbon ff x 8 = 10' 5 per cent, of metallic iron is added to 

 the bath, making a total increase of 5'G + 10'5 - 5 = ll'l 

 per cent., or a charge of 420 Ibs. of forge pig metal, ought to 

 yield 4G6 Ibs. of wrought metal, whereas from an ordinary 

 puddling furnace the actual yield would generally amount to only 

 370 Ibs. (or 12 per cent, less than the charge), showing a difference 

 of 96 Ibs. between the theoretical and actual yield in each charge. 



This difference, amounting to fully 20 per cent., is due to the 

 enormous waste by oxidation to which the iron is exposed after it 

 has been " brought to nature " (by the removal of the carbon) ; 

 when it is in the form of a granular or spongy metallic mass and 

 during the process of forming it into balls. So great a waste of 

 metal by oxidation seems at first sight almost incredible, but 

 considering the extent of surface exposed in the finely divided 

 puddled mass, it is not at all exceptional, and is in fact almost 

 unavoidable in a furnace of the ordinary construction, maintained 

 as a puddling furnace is, at a welding heat. Many attempts have 

 been made, for example by Chenot, Clay, Renton, and others, to 

 produce iron directly from the purer ores, by reducing the ore in 

 the first instance to a metallic sponge, and balling up this sponge, 

 which is a loose porous mass, somewhat similar to spongy puddled 

 iron, on the bed of a furnace, but all these attempts have failed, 

 simply on account of the great waste of iron, a waste amounting 

 to from 25 to 50 per cent., in balling up the sponge. Indeed, the 

 loss in an ordinary puddling furnace would probably be greater 



