214 ANNUAL OF SCIENTIFIC DISCOVERY. 



pie, have been looked upon the minute proportions of manganese founci in 

 some descriptions of steel, and also the appearance of nitrogen developed 

 during analytical operations. The former (howsoever its presence may be 

 considered to modify some mechanical property of the steel) has never been 

 deemed essential to its chemical composition when the steel is in its normal or 

 pure state; whilst the latter has ever been held (when recognized or detected 

 at all) as the result of some merely mechanical adherence of that element to 

 the metal, or to have been derived from the reagents present on analysis. 

 The same reasoning has applied to some other (so-called) foreign or acci- 

 dentally present matters ; and steel has, consequently, ever since the doc- 

 trines of modern chemistry began to be applied in reasoning upon it, been 

 looked upon as simply a compound of iron and of carbon, and as such, and 

 such only, it would appear to be held to be even up to the present hour. 



The same chemical doctrine of composition has always influenced, and 

 still continues to influence, the selection of materials to be used as reagents 

 in the formation of steel, or for the conversion of iron into steel. Hence, to 

 effect this conversion, it has ever been deemed needful only to bring heated 

 iron in contact with carbon, or with some carbon compound, in order that 

 the iron shall take up the one per cent, or thereabouts, considered as essen- 

 tial to- steel ; and hence, also, the selection of charcoal as this reagent prin- 

 cipally; and whenever other reagents may have been taken and used as 

 aids or substitutes leather shavings, for example this selection also has 

 always been made on the same general principle that it was the carbon alone 

 that was to be absorbed by the metal. It will be seen, however, that, not- 

 withstanding this guiding idea of the steel-makers, either accident alone, or 

 some theory of the quality of the carbon in these specially selected matei'ials, 

 has undesignedly led to the employment of the very elements along with the 

 carbon that the production or the chemical composition of steel demands, 

 and which other elements existing theory would have either altogether 

 rejected, or certainly never have especially sought for. 



Bearing in mind the broad facts as seen in the distinctive physical proper- 

 ties of steel and of iron, and the unsatisfactory character of the carbon-per- 

 centage explanation of these remarkable distinctions, is it not possible that 

 a careful examination of the daily operations used to produce steel may 

 exhibit the existence of some other phenomena, or the action of some other 

 elements playing as important a part, either in the operations or in the ulti- 

 mate composition of the steel, as that hitherto supposed to be fulfilled by 

 carbon alone? 



Before proceeding with my examination of already known facts, under 

 which iron is converted into steel, or steel converted into iron, or before 

 instituting any special line of research for developing new facts upon which 

 to reason as to the actual conditions and results, mechanical or chemical, of 

 conversion, it is needful to define what steel really is, physically; that is, 

 what distinguishing properties it possesses, which, taken independently of 

 its chemical composition, shall constitute an easy and incontrovertible test; 

 or, in other words, shall enable us clearly to distinguish steel proper from iron 

 compounds, or alloys of iron with other metals, or mixtures of iron with 

 non-metallic elements, which in some respects resemble but are not real steel. 



Steel is contradistinguished from all other compounds by its capability of 

 receiving different degrees of hardness, and a degree of hardness compara- 

 tively superior to any other metal ; by its elasticity under certain kinds of 

 treatment, its capability of receiving a fine and a peculiar polish, by its devel- 



