CHEMISTRY. 177 



tains more than 2 or 3 parts in 10,000. One part of silicon 

 in 1,000 of Bessemer metal, renders it hard and brittle when cold. 

 In ordinary Bessemer pig iron, it is present in quantities varying 

 from 1 to 4 per cent. The author gave it as his opinion, from ex- 

 perimental inquiries, that silicon is dissolved or "occluded" in 

 iron in the same way that carbon is, but that the solvent power 

 of the metal is so much greater for silicon than for carbon that it 

 is quite a rare thing, even if it ever occurs, for silicon to separate 

 in a free state from the iron. Mr. Bessemer confirmed the re- 

 marks of Mr. Snelus as to the universal presence of silicon even 

 in the best Sheffield steel ; and alluding to the prevailing opinion 

 that the presence of silicon was injurious, stated as his opinion 

 that, on the contrary, the presence of a small quantity of silicon 

 was beneficial. Eeported in Nature, Sept. 15, 1870. 



THE CHEMISTRY OF THE BESSEMER PROCESS. 



At the Troy Meeting of the American Association for the Ad- 

 vancement of Science, Lieut. C. E. Button, U. S. A., read a paper 

 on this subject, of which the following is an abstract : 



" Cast iron the raw material from which the malleable metal 

 is made may be formulated approximately as follows : 



Silicon (Si), 5 to 3 per cent. 



Phosphorus (P), 05 to 2 per cent. 



Manganese (Mn) , to 20 per cent. 



Sulphur (S), 25 to 2 per cent. 



Carbon (C), 2 to 5 per cent. 



Iron (Fe), - 90 to 96.5 percent. 



*' It is a rare thing if pig iron do not contain every one of these 

 elements, excepting manganese, in proportions within the limits 

 here given. Although manganese is oftener absent than present, 

 yet its importance is so great in the metallurgy of iron, that I 

 have deemed it necessary to introduce it into the discussion, par- 

 ticulary as its importance is greatest of all in the Bessemer pro- 

 cess. The percentages given are neither the highest nor the 

 lowest, but may be considered as the extremes of the normal 

 varieties. Some few extraordinary brands have been known to 

 exhibit very remarkable constitutions, such as 8 per cent, of 

 carbon, and 12 to 15 per cent, of silicon; but these are 

 mere curiosities of metallurgy, and not useful or practicable 

 materials." 



All these elements are readily oxidized, and, accordingto Lieut. 

 Button, in the order in which they have been mentioned, the car- 

 bon being the last impurity to be burned out. After reviewing 

 the ordinary methods of converting cast iron into wrought iron and 

 the order and manner of the elimination of the various injurious 

 substances, Lieut. Button says : 



" There is not a substance employed, nor a combination induced 

 or resolved, in the Bessemer process, which has not been re- 



