6 Lange, Some Remarkable Steel Crystals. 



As remarked at the beginning of this communication, 

 the formation of crystals of iron or steel having truly 

 geometrical boundaries is of rare occurrence. The question 

 might then be asked in what manner is the crystallization 

 of steel revealed in its solidification from the liquid state 

 in the ordinary way, where the mass of the steel prevents 

 the formation of freely developed crystal forms owing to 

 the mutual interference of the crystal growths. 



Tschernoff assumes that iron solidifies not in approxi- 

 mately parallel layers, but by the growth of " pine-tree " 

 crystals {Revue Universelle, ser. 2, vol. 7, 1 880). I have myself 

 seen the etched surface of the whole longitudinal section 

 of a large steel ingot, the structure of which at some 

 distance suggested the appearance of interlacing branches. 

 However this may be, this tendency is not independent 

 of other physical circumstances, for it has been observed 

 that the interior of " bled " ingots, that is to say, ingots 

 from which the interior has escaped after partial solidifica- 

 tion, is always smooth. We also know that iron or steel, 

 like many other metals, when solidifying in a mould 

 through the walls of which the heat is rapidly conducted 

 away assumes a strongly columnar structure. 



Many years ago Mliller, in Germany, conducted a 

 series of experiments on steel ingots to determine the 

 stages of the growth of blowholes, and to do this he 

 poured out the interior of partly frozen ingots at various 

 stages of solidification. He invariably found the interior 

 surfaces smooth and without any surface protrusion of 

 crystal growths {Iroti, January 5th and September 14th, 

 1883). It would appear, therefore, that the solidification of 

 steel in the ordinary way proceeds in smooth parallel layers 

 in spite of a strong columnar structure, or, at all events, 

 the growth of the crystals keeps absolute pace with the 

 solidification of the steel. You will notice this columnar 



