Manchester Memoirs, Vol. Iv. (191 1), No. ^4. 13 



iron, which are occasionally found in furnace hearths or 

 slag masses. A good example of this formation was once 

 sent to me by the late Mr. H. A. Hoy, which had been 

 taken from a pocket in the hearth of one of the steel- 

 melting furnaces of the Lancashire and Yorkshire 

 Railway Company at their Horwich works. Prolonged 

 exposure to a temperature not far removed from the 

 melting point had oxidised away the carbon, silicon and 

 manganese, whilst by absorption and concentration, the 

 phosphorus content had increased to a remarkable extent 

 as the following analysis of the sample shows : — 



Analysis of Horwich "'Furnace-Crystals''' ? 

 Combined Carbon ... ... nil 7 



Silicon ... 



Manganese 



Sulphur 



Phosphorus 



Iron 



trace „ 

 nil „ 

 •02 „ 

 36 „ 



9962 „ 



The external appearance of the metal resembled a mass of 

 crystal surfaces, mostly pentagonal, with smooth flat faces, 

 some being of considerable size. These might, at first 

 sight, appear to furnish proof of a definite form of 

 crystallization, but this is not actually the case. Their 

 formation was due to the constant growth of the granules 

 under the combined influence of time and heat ; and the 

 effects of expansion and contraction upon groups of such 

 granules in their plastic condition produced the forms of 

 pentagonal dodecahedra such as are produced by the 

 compression of plastic spheroids. This would be helped 

 by the liquation of the more fusible phosphide of iron 

 between their cleavage planes. On breaking up the mass 

 when cold the lines of fracture would be along the brittle 



