268 ANNUAL OF SCIENTIFIC DISCOVERY. 



pig metal are used, and the remainder is made of bar iron; these proportions 

 would produce a cast steel suitable for most purposes. Thus, for cast steel to 

 be manufactured into edge tools, ten pounds of pig metal are added to thirty 

 pounds of bar iron. For table knives, eight pounds of pig metal are combined 

 with thirty-two pounds of bar iron ; and for hard steel, twelve pounds of pig 

 metal are added to twenty-eight pounds of bar iron. But as almost all irons 

 differ in hardness and quality, these proportions must, to a slight degree, be 

 modified according to the judgment of the melter." 



ON THE MANUFACTURE OF IRON. 



The following is an abstract of a paper read before the London Society 

 of Arts, by Prof. Calvert : 



After pointing out what were believed to be the causes of inferiority of 

 iron, in many works, apart from the varying qualities of the ores, the injurious 

 action which an impure fuel had upon the quality of the iron was particularly 

 alluded to ; and the necessity of removing the sulphur from the coal or coke, 

 when employed in the blast furnaces, before it could be imparted to the cast 

 iron during the process of smelting, was strongly enforced. 



Prof. Calvert then referred to several instances in which the quality of iron, 

 after the application of the chloride of sodium in the blast furnace, had been 

 greatly improved. These improvements were described to have been effected 

 at a very small cost, by the following simple process. If the blast furnace 

 was worked entirely with coal, chloride of sodium was added, with each 

 charge, in proportion to the quality of the ore and flux employed ; but a 

 better result was produced if the coal was previously converted into coke, 

 and an excess of the chloride was used in its preparation, in order to act on 

 the sulphur of the coal and of the ore should any be found therein ; and a 

 greater improvement was manifested in the quality of the iron, when only 

 coke so prepared was used in the blast furnace. The coke, so purified, emit- 

 ted no sulphurous fumes when taken out of the coke oven ; nor when extin- 

 guished with water did it give off the unpleasant odor of sulphuretted 

 hydrogen, nor was there any sulphurous acid gas liberated, during the opera- 

 tion of smelting iron in the cupola, or in raising steam in the locomotive 

 boiler, by coke so prepared ; and it was stated that these decided advantages 

 were gained, in some cases at an additional cost of only one penny per ton of 

 fuel. Prof. Calvert then gave the results of a series of experiments which had 

 been made upon trial bars one inch square, cast from iron melted hi the 

 cupola, with coke prepared by his process. He exhibited specimens of the 

 iron so prepared, when the closeness of texture and the absence of the " honey- 

 comb " appearance prevailing in the iron cast with the ordinary coke, was 

 clearly demonstrated. 



The mode of experimenting was described, and the results were given very 

 elaborately, and it was shown that the average increase of strength was from 

 10 to 20 per cent. 



Taking the mean of the whole experiments, the following conclusions were 

 arrived at: The mean breaking weight of the bars, 1 inch square, smelted 

 with the improved coke, was 515-5 Ibs.; ditto, with extraordinary coke, 427-0 



