232 ANNUAL OF SCIENTIFIC DISCOVERY. 



By the aid of this coke the English blast furnaces produce 120,000, 

 to 200,000 kilogrammes of iron each week, when by the employment 

 of charcoal the quantity produced would only be 20,000 to 30,000 

 kilogrammes. 



IMPROVEMENTS IX THE MANUFACTURE OF IRON AND STEEL. 



A Parisian, says the London Mechanic, has patented a method of 

 manufacturing malleable iron and steel from decarbonated cast iron, 

 without casting, by heating it in contact with a metallic oxide, or a 

 carbonate containing a sufficient proportion of oxide, and then rolling or 

 hammering it without previous puddling. The cast iron to be con- 

 verted should be cast in bars or plates, in such a way that the bubbles 

 or impurities may form the end of the bar or plate, and be cut off 

 with the rough end, instead of being distributed over the entire sur- 

 face ; and the bars or plates should also be of such size that, when 

 extended by rolling, they will give the required form of bar or plate 

 to be produced. The substances used for effecting the conversion 

 of the cast iron are protoxide of zinc and calamine ; but the oxides 

 of iron, red oxide of manganese, deutoxide of copper, protoxide of 

 tin, or oxides of lead may also be employed. The protoxide of zinc 

 calamine, and the oxides of iron, when not too large a proportion of 

 silica therein, are the most suitable. The quantities of oxide em- 

 ployed will vary with the degree of decarbonization to be effected. 

 The cast-iron bars or plates to be converted, having been placed along 

 with a proper quantity of the particular oxide employed in a cement- 

 ing a case, are raised to a cherry-red heat in a suitable furnace, and 

 kept at this heat till the process is completed. The rate at which the 

 process proceeds is one third of a line from each surface in 25 hours. 

 For making steel, a less quantity of oxide is used, or the process con- 

 tinued for a less time. The metal is then extended by rolling, and the 

 rough ends cut off. It is then fit for market. 



BURNT LIME AS A FLUX. 



The study of the gases formed in blast-furnaces, with which the 

 authors have been engaged for some years, has shown that the use of 

 carbonate of lime as a flux is attended with great loss, and likewise 

 that this loss may be obviated by using burnt lime instead. The ^ases 

 were taken from a blast-furnace, 54 feet high, at Ougree, at thirty- 

 two places, 1 foot apart, and the per-centage of carbonic acid deter- 

 mined. 



It ;s evident from the examinations, that the carbonic acid is formed 

 on the first introduction of atmospheric air, and within a remarkably 

 short distance is reduced to carbonic oxide, for the gas 8' above the 

 tuyere does not contain a trace of carbonic acid ; however, the zone 

 from which carbonic acid is entirely absent is of very limited extent ; 

 from 9' to 10' above the tuyere the gas again contains carbonic acid, 

 and in no inconsiderable quantity. 



