840 Janoyer on the Injluence of Sulphur on Iron, 



m q 



would be disadvantageouSj as in tte manufacture of nails Tliere 

 is often also a demand for certain purposes for brittle iron. 



It has indeed been remarked, but without explaining the fact, 

 that certain coarse-grained *' cold-short" irons forge very easily. 

 "VVe must not conclude from this (which has often been done), 

 that all "cold-short" coarse-grained irons are always good when 

 hot. In fact, a bad iron may be charged with silicium for in- 

 stance, which will make it "hot-short" as well as "cold-short," 

 and which will not work nearly as well as a fibrous iron well 

 prepared and free from silicium. It is then necessary to ascer- 

 tain first that the irons are cold-short from the presence of a 

 small quantity of phosphorus, and not from the presence of an- 

 other ingredient, or some cause inherent in the metallurgical 

 treatment. 



In all the experiments on a grand scale, made to favor the pas- 

 sage of the phosphorus into cast iron without compromising its 

 quahty by introducing silicium, I have always observed that the 

 result from a charge containing equal quantities of clay and car- 

 bonate of lime was the best. In this case the slags have the fol- 

 lowing composition : 



Oxygen, 



Silica, 48-07 pr. ct. 24*97 24-97 



Alumina, - - • . 15'94 7*44 



Lime, 35*99 lOll 



1755 



These slags are well suited to a good result ; for without being 

 too silicious they are not injurious to the quality of the iron, in 

 facilitating the reduction of the silica ; neither do they contain 

 too great a quantity of base ^ prevent the decomposition of the 

 phosphates in the bed of fusion and the passage of the phospho- 

 rus into the cast iron. 



In conclusion I will allude here to the memoir of M. Stengel, 

 (Ann. des Mines, t. x, 3d serie), who pretends to have assayed 

 very sulphurous irons which were not in the least degree "hot- 

 short." He contends that it is to copper that this property of 

 iron must be attributed. Every one knows in fact that a feeble 

 quantity of copper prevents iron fi-om welding and renders it 

 "hot-short" in a high degree. But I will say in opposition to 

 M. Stengel, that this quality cannot ordinarily be attributed to 

 copper, copper being very rarely present, but as a general thing, 

 to the presence of sulphur. Besides, in all the trials on a large 

 scale which I have made with care, if copper had been the cause 

 of the "hot-short" iron which was obtained, there would have 

 been **fers de couleur" at the time of treatment with charcoal 

 as well as when the mineral coal was used, which was by no 

 means the case. 



When the irons obtained in la Bourgogne and la Franche- 

 Comte by the use of charcoal and those derived from the same 

 ores treated with mineral coal in the furnace of la Loire or the 



