CHEMISTRY. 179 



converter at a very high temperature. Hence will be seen the ne- 

 cessity of employing irons containing high percentages of silicon. 

 At least 2 per cent, of this element is essential, any less quantity 

 \jeing insufficient to generate heat enough to keep the iron thor- 

 oughly liquid and fluent until the end of the casting process. It 

 is often asserted that irons for Bessemer conversion must be 

 4 gray irons, 1 as they are called, that is, irons rich in carbon. 

 Now, although this happens, as a rule, to be true enough, it is 

 apt to lead to misapprehension. The fact that Bessemer pig irons 

 are carbonized varieties is an accident and not an essential feat- 

 ure. What is essential is that it should contain a large quantity 

 of silicon, and very little indeed the least possible of sul- 

 phur, phosphorus, and manganese. ISTow, a pig iron containing 

 much silicon, and no sulphur or manganese, is pretty sure to con- 

 tain a high percentage of carbon, as all smelters are aware. This 

 fact is a feature of the blast furnace, and almost without excep- 

 tion. If an iron could be produced with much silicon, a little car- 

 bon, no phosphorus, it would, I think, be not altogether unsuited 

 to the Bessemer treatment. In a word, the quantity of carbon is 

 approximately immaterial except so far as it implies proper con- 

 ditions with respect to other elements. The main element re- 

 quired is the silicon, and not the carbon. 



" Of equal importance and absolute necessity is the absence of 

 phosphorus. This element is the arch-enemy of the iron-maker, 

 but it is the very scourge and pestilence of the steel-maker. I 

 venture to assert that the most formidable problem which has 

 arisen with respect to any process dealing with iron or steel is the 

 phosphorus problem in the Bessemer converter. A few pounds 

 of phosphorus in a ton of Bessemer railway bars render them 

 unfit even for the scrap-heap. Fifteen-hundredths of one per 

 cent, of it i sufficient to render common wrought iron worthless, 

 but one-tenth of that quantity will ruin Bessemer metal past all 

 remedy. But the smallness of the quantity which is capable of 

 working this terrible destruction is by no means the worst evil. 

 There are two other circumstances of an appalling nature, namely, 

 the almost universal presence of phosphorus, and the absolute 

 impossibility of eradicating it by any process at present known. 

 " I have already ventured the opinion that phosphorus increases 

 its affinity for iron with every increase of heat, at least rela- 

 tively, if not absolutely. This fact seems to be absolutely. If 

 we accept it, we can instantly explain what seem, otherwise, to 

 be many anomalies and contradictions. It will explain to us 

 why, in the great heat of the blast furnace, it leaves every 

 other combination, and enters the iron ; why, in the much lower 

 heat of the puddling furnace, it seems to waver between staying 

 with the iron, or forming a new alliance with oxygen, ready to 

 choose either at the influence of any third substance which may 

 affect the question ; why, in the Bessemer process, it clings to the 

 iron with a desperate tenacity which nothing seems able to re- 

 solve. These three facts then are all of them formidable : 1st. 

 That a minute quantity of phosphorus is capable of working 

 terrible injury, and that it is omnipresent throughout nature; 



