8io THE POPULAR SCIENCE MONTHLY. 



alternately in the same finery. This furnace, in its simplest form, 

 consists essentially of a shallow quadrangular hearth, formed of cast- 

 iron plates. In one side is a tuyere, inclined at an angle of 10 to 

 15. The bottom is kept covered with a layer of charcoal. In the 

 Siegen district, a piece of pig-iron, weighing fifty to sixty pounds, is 

 placed on the hearth, having been previously heated ; the hearth is 

 then three parts filled w^ith burning charcoal ; on it is placed a portion 

 of the cake produced in the last operation, w^hich has been kept hot in 

 burning charcoal, at the back of the furnace. The remainder of the 

 hearth is then filled up with charcoal. The other six or seven pieces 

 into which the last cake was divided are placed on the top. In this 

 process, the production of steel and the reheating of that obtained in 

 the last operation, preparatory to working it under the hammer, are 

 conducted together. The blast is turned on. The i)iece of pig-iron 

 forms into a pasty mass ; cinder, rich in oxide of iron, produced in the 

 latter part of the preceding operation, is then thrown in ; a second 

 piece of pig-iron, weighing about one hundred pounds, is added, and 

 afterward four or five pieces of spiegeleisen (cast-iron, containing 

 manganese), weighing each about a hundred pounds, are successively 

 added. If the metal is found to be too much decarburized, more 

 Spiegel is added. In this process, as in the Catalan, it is impossible to 

 obtain a homogeneous product. The principle in both is essentially 

 the same, viz., decarburization by oxide of iron. In this process, as in 

 every other process for the production of steel, manganese is used 

 with great advantage an advantage which arises from its power of 

 rejDlacing iron in the slag and of forming a slag that is more liquid 

 than one containing iron alone. 



The essential difference between the finery and the puddling proc- 

 ess consists in the use of a reverberatory furnace, the mani2)ulation 

 of the metal and the regulation of the temperature being thereby 

 greatly facilitated. The decarburization is effected by the addition 

 of oxide of iron produced during rolling, and partially by the air 

 which enters the furnace as the metal melts slowly down ; manganese 

 is added during the process. It is important that the temperature 

 should be kept low. It is difficult to weld this steel perfectly, because, 

 probably, the temperature at which it has to be worked is too low to 

 make the cinder sufficiently liquid to enable it to be squeezed out 

 under the hammer to the same extent that it is in the case of malle- 

 able iron. This difficulty has, however, been got over by completely 

 fusing the steel before working it, so as to enable the slag to sej^arate 

 completely. In this form metal manufactured by this process has 

 been largely used by Krupp. 



The principle which regulates the production of steel by these 

 methods is taken advantage of in the Uchatius process, in which pig- 

 iron is first granulated by running it while molten into cold water. The 

 granulated metal is then mixed with about twenty per cent, of roasted 



