1892.] NEW-YORK MICROSCOPICAL SOCIETY. 73 



This contains the desired carbon, manganese, and silicon to pro- 

 duce the grade of steel desired. 



The product is then poured from the converter into the casting 

 ladle, and from the latter into cast-iron ingot moulds of 14^ or 16 

 inches square, or 16 by 19 inches on the base, as the case maybe. 

 These moulds stand vertically in pits and are filled with 4 or 5 

 feet of molten metal. Chilling and congelation begin as soon as 

 the metal is poured ; crystallization forming structure in the in- 

 got, the character of which is dependent upon the grade of the 

 steel, its impurities, size of the ingot, rate of solidification, and 

 particularly the rate of cooling. 



In Bessemer rail-steel ingots of 14^ inches or 16 inches square 

 on the base, of the grades of .50 and .60 carbon, the chilling of 

 the exterior surfaces in contact with the mould induces a decided 

 columnar structure, extending at right angles from the mould i 

 to 3 inches into the interior of the ingot, then there is more de- 

 cidedly polyhedral structure to the centre of the ingot. In the 

 upper portion of the ingot a pipe is apt to develop, also gas cavi- 

 ties. In the pipe and cavities traces of crystals are present, the 

 former especially often being studded with perfect forms of pine- 

 tree crystals. 



In the blow holes, in the columnar structures of the grades of 

 steel mentioned, I have always found traces of crystallization. 

 There seem to be two systems, in which the main axes are in 

 parallel rows, the lateral axes appearing at right angles to the 

 main axes, forming a series of projecting points at right angles to 

 one another in two directions ; in the other system the base of 

 the points seemingly being surrounded by hexagons. 



Specimen No. 10 shows the decided columnar structure of the 

 exterior of a .60 carbon ingot. In another specimen of a lower 

 grade of steel blow holes have formed in the columnar structure. 



Returning to specimens Noi. 8 and 9, which formed a trans- 

 verse section from the exterior to the centre of the ingot, the ex- 

 terior blow holes may be noticed, though the columnar structure 

 has been modified by long-continued heat, while the polyhedral 

 structure has been more strongly developed than usual. The 

 mould could not be stripped from this ingot, and was broken un- 

 der a drop, and in doing so the ingot was broken. The ingot was 

 many hours in cooling, and quite well-developed octahedral crys- 



