CHEMICAL SCIENCE. 231 



of sulphur in iron diminishes its value, principally by rendering it 

 brittle at a red heat. The sulphur which the iron contains is rarely- 

 derived from the ore, but principally from the fuel employed. Search- 

 ing for a method which would enable me to decompose the mineral 

 sulphides, as also those of the fuel, after many trials I discovered that 

 chloride of sodium (common salt) applied in a certain way, and in 

 suitable proportions, would accomplish the end I proposed, and this 

 in consequence of the following chemical reaction. 



By the influence of heat, the bisulphide of iron is decomposed into 

 the protosulphide of iron, which again, in contact with the chloride 

 of sodium, forms chloride of iron and sulphide of sodium ; the former 

 at a high temperature, in the presence of watery vapor is decomposed 

 into protoxide of iron and chlorohydric acid, while the latter passes 

 off in the slag or scoria of the furnace, and consequently the sulphur 

 is not fixed by the iron. This process, which I have tried on a large 

 scale at three manufactories, has afforded very satisfactory results. I 

 would remark that the iron which I have the honor to submit, was 

 obtained at the same kind of furnace, and under similar circumstances, 

 as the ordinary iron, except the application of my process ; the crys- 

 talline structure of the iron, which diminishes its tenacity, it will be 

 remarked, has disappeared, and it has become fibrous and very tena- 

 cious. In the case of the malleable iron, I have not been able to 

 determine exactly the ratio of the tenacity which the purified iron 

 presents, compared with that prepared in the usual manner ; but I 

 have determined the comparative resistence to fracture of two bars 

 of cast iron ; the bars were 1 inch diameter and 5 feet long, placed 

 upon two supports distant 4 feet 6 inches. A gradual pressure was 

 applied to the centre of the bars until fracture occurred. Pounds 

 required to fracture the unprepared cast iron: 487,456,487,470; 

 pounds required to fracture the purified cast iron: 556, 525, 544, 

 562, 569, 544. 



The same specimens of iron were analyzed, and the unpurified was 

 found to contain ygVg- ^ su ^P uur ? while the purified did not contain 



over T^O- 



I have applied the process to the combustion of coke on a large 



railway in England ; and it has proved that during the combustion, 

 the sulphur was not at all set free, confirming what I have above 

 advanced, that it remains in the cinders, so that it does not attack the 

 copper coverings of the fire-boxes or the brass tubes, resulting in a 

 great economy. At some future time I shall take the liberty to submit 

 to the Academy the difference in wear of a locomotive in which rny 

 coke is burnt, and one used with the ordinary fuel. 



I have obtained at Manchester, by the employment of prepared 

 coke, very satisfactory results by refining the cast iron in the cubilots ; 

 iron of the same quality melted in the same cubilot, with coke of the 

 same kind, was during the operation purified, and acquired great 

 tenacity, as shown by the numbers below. 



Bars of Cast Iron, 1 inch diameter 4 feet 6 inches long (ordinary coke) 514 Ibs. 



(prepared coke) 528 Ibs. 



