284 THE SCIENTIFIC PAPERS OF 



of scrap iron or of ores in a more or less reduced state in a bath of 

 intensely heated pig metal. These processes have now received 

 very considerable practical development at the works of the Lan- 

 dore Siemens-Steel Company, of Messrs. Vickers and Company of 

 Sheffield, and at several other works. Two processes are employed 

 at these works, the Siemens-Martin process, which consists in dis- 

 solving scrap metal or steel in a bath of pig metal to which spiegel- 

 eisen is finally added, and the ore-reducing process in which pig 

 metal and ore in a more or less reduced condition are employed. 



The process chiefly employed at the Landore works consists of 

 introducing on the bed of an intensely heated regenerative gas 

 furnace, as shown in Plates 43 and 44, about six tons of pig metal, 

 which may be No. 3 or 4 hematite pig. When a fluid bath has 

 been formed, oxide of iron (which should by preference have been 

 melted beforehand with such proportions of lime or other fluxing 

 materials as to form with the silica in the ore and in the pig metal 

 a fusible slag) is added, or natural ores may be used in their raw 

 condition if they contain lime and manganese, as, for example, the 

 African Mokta ore. When about 30 cwt. of this ore have been 

 dissolved (with ebullition) in the metallic bath, it is found that a 

 sample taken from it contains only about O'l per cent, of carbon ; 

 a point which can easily be detected by the eye of the workmen 

 owing to a peculiar bright appearance of the sample when chilled 

 in water and broken by the hammer. 



In order not to pass beyond this point, samples are taken out 

 from time to time during the latter part of the operation, and 

 such a series of samples, which have been kindly supplied to me 

 by Messrs. Vickers and Co., together with samples of steel made 

 by the process, are now placed before you. The requisite point of 

 decarburisation being reached, the supply of ore must be stopped, 

 and from 8 to 10 per cent, of ferro-manganese or spiegeleisen 

 added to the bath. When this has been well incorporated by 

 stirring, the metal is ready to be tapped into a ladle mounted 

 upon wheels, which is afterwards propelled into the foundry, and 

 discharged either into ingot moulds, to be hammered and rolled, 

 or into dried clay moulds for the production of steel castings. 



Considerable difficulty was experienced to find a material to 

 resist the excessive heats necessary for carrying out this process ; 

 ordinary Dinas bricks, which are considered the most refractory 



