I 



Janoyer on the Injiuence of Sulj}hur o7i Iron, 339 



The only difference in the results is in the carbon; and it fol- 

 lows, as before stated, that the loss of sulphur is to be attributed 

 to its combination with carbon ; a combination facilitated hj the 

 presence of phosphorus, which tending constantly to form a phos- 

 phuret of iron rej^laces a certain quantity of carbon. 



We thence naturally infer that irons are less *' hot-short" 

 which are obtained with a mixture of phosphatic ores, because 

 of the tnjluence of pJios^korus in neutralizing partially the action 

 of sulphur in the irons. 



These explanations give us also an explanation of a known 

 fact m practical metallurgy, the explanation at present given be- 

 ing insufficient although partly true. There is no practical me- 

 tallurgist who in treating very phosphatic ores has not obtained, 

 contrary to his expectation, with a proper heat and slags, indi- 

 cating a complete reduction, — some cast iron completely white. 



It has always been supposed that phosphorus gave too great 

 fusibility to the mass and accordingly prevented the formation 

 of a gray iron. But to this explanation, which has some truth, 

 there must be added the loss of carbon caused by the tendency 

 of phosphorus to form a phosphuret of iron. For if the fusi- 

 bility were the only cause, the slags should be slightly charged 

 with iron, "which is not the case* In all the synthetical trials and 

 analytical results obtained, we find that phosphorus serves to 

 remove a portion of the sulphur probably by favoring the sepa- 

 ration of the carbon of the cast iron which then comoines with 

 the sulphur to form a sulphid of carbon. 



Moreover, phosphatic irons, according to Karsten (Manuel de 

 Metallm^gie), preserve better their neat^ pass more quickly to a 

 white heat, a heat Avhich spreads uniformly through the whole, 

 whilst sulphurous irons, and as a consequence those '^ hot-short," 

 cool rapidly and very unequally. The bar of forged iron in this 

 condition presents no homogeneity, and breaks very easily. 

 Hence in certain cases the influence of phosphorus, which is 

 generally considered very injurious, may perhaps be advanta- 

 geous. The metallur^st should use it with moderation, avoiding 

 too great a quantity m the bed of fusion, as it is known that 

 after cooling completely, phosphatic irons are brittle. 



It is therefore necessary before using it to ascertain the re- 

 quired amount by a series of experiments on a large scale. These 

 experiments should be made with much care, for, according to 

 Karsten, it is known that the extreme limit of phosphorus in a 

 good iron is O'SO percent; if this quantity is exceeded the irons 

 lose their tenacity when cold and will not resist a shock or blow. 

 Very phosphatic and "cold-short" irons have ordinarily a 

 grained fracture, with brilliant facets, without any fibres like 

 i^any strong irons. The practical metallurgist ordinarily selects 

 them for uses Tvhcre the very soft slightly '* hot-short" irons 



