226 ANNUAL OF SCIENTIFIC DISCOVERY. 



ON SOME POINTS OF CHEMICAL INTEREST CONNECTED WITH THE 



. BESSEMER PROCESS. 



The following abstract of a communication, presented to the American 

 Academy by Dr. A. A. Hayes, on the above subject, embraces many points 

 of interest. 



It is well known that Mr. Bessemer has based his improvements on the 

 startling novelty of making crude iron nearly pure, without the aid of tire, 

 from carbonaceous matter. In considering the ordinary mode of refining 

 crude iron, the final operations being performed on crude pig, or on partially 

 refined pig-iron, w r e have, as one of the conditions of success, the application 

 of an intense heat, and the presence of more or less atmospheric oxygen, nec- 

 essary to maintain the required degree of fluidity in the mass of iron, and to 

 burn out the carbon and other impurities present. As the iron loses its car- 

 bon and other extraneous substances, it becomes less fusible, and the work- 

 man, stirring the mass as it begins to lose its fluidity, gathers into rough 

 masses the aggregated particles, which are always spherical in general 

 form. From the masses, which are very porous and unequal, a bar of 

 regular form is obtained by the usual means of pressing, or hammering and 

 rolling. 



" There is in this process strictly a segregation of particles of pure iron 

 from the crude mass, which, under the agitation of stirring, unite to form 

 rounded aggregations; and the heat of the furnace being increased, the 

 separation of pure iron continues, until the melted impurities alone remain. 

 The change of crude to pure iron is accompanied by ihs production in part of 

 the impurities which remain; they arc not educts. Aside from the loss of 

 carbon in the form of carbonic oxide, the phosphorus and sulphur, which 

 my experiments have proved are always united to the metallic bases of the 

 earths or alkalis, with these bases, burn into oxidized products; while the 

 silicium and a portion of the iron, also oxidized, form the melted slag, or 

 cinder, as an additional foreign matter. To the loss of impurities we must 

 also add the weight of iron burned in forming secondary products ; so that, 

 if the operations were performed on crude iron containing ninety-two per 

 cent, of pure iron no more than eighty-two per cent, of malleable iron will be 

 obtained. By the method of Bessemer, crude iron in a melted state is 

 exposed, in a nearly closed receptacle, to jets of air forced into and under the 

 fluid; and it is alleged that such an excess of heat is produced in the process, 

 'that the metal continues to boil even after the blast has ceased/ The 

 direct statement is made, that ' air, dividing into globules, and diffusing 

 itself among the particles of fluid iron, and thus coming in contact at 

 numerous points with the carbon contained in the crude iron, and producing 

 thereby a vivid combustion/ and the same action is implied in other parts 

 of Mr. Besscmer's patent-specification. 



" Now, it is well known to chemists, that the combustion of the carbon of 

 crude iron cannot take place under the conditions. This carbon exists in gray 

 iron in the allotropic state of graphite, and is not combustible even alone, 

 when exposed highly heated to a current of atmospheric air. We burn it in 

 the laboratory by the application of oxygen in some condensed state only. 

 The proper chemical explanation of this point is a very simple one. Iron, 

 which is a highly combustible body at ordinary temperatures, has its attrac- 

 tion for oxygen enormously increased by the heat of fluidity, and in combin- 



