CHILLED IRON. 



17 



over the surface of muoli-worn chilled rolls used in slioct 

 mills. In such cases the sheets get a faint diaper pattern 

 impressed upon them. The opening of crack spaces points 

 to lateral shrinkage of the portions of chilled material they 

 surround, and to some release from a state of involuntary 

 tension. If tliis action is accompanied by some actual densi- 

 iicatlon of the lissnred chill, then we have a result that possible 

 conflicts with the example of condensation from chilling cited 

 by Dr. Percy. After expressing a hope that a good trade in. 

 corn-milling chilled rolls may grow up in Bristol, the papoi' 

 con<;ln(k:d with an inquiry as to tlio most economical and 

 least troublesome means of eitlier breaking up or raoltinf 

 worn-ont sheet rolls, some of which occasionally consist of 

 lumps of three tons weight. 



DISCUSSION. 



Mr. de SoTEES had always remarked tho surprising con- 

 solidation and absence of honeycombing in the bodies of 

 broken chilled rolls. He did not think it was usual in 

 this country to use a pouring head of so groat a height 

 (with corresponding augmented liquid pressure) as men- 

 tioned by tho author of the paper. Whore an open-hearth 

 melting plant existed, tlie melting down of old rolls was not 

 difficult nor expensive. He agreed with much that had been 

 said as to tho importance of pig mixtures and uniformity of 

 melting. 



Prof. Ryan referred to the chemical composition of cliill- 

 mg-iron mixtures as being of importance, and ho advanced 

 views to account for tho cracking which develops in chilled 

 surfaces subjected to heat dni-ing wear. 



Mr. SuTCLiFifE drew attention to tho comparative effect of 

 radial and tangential "gates" for introducing the molten 



p 



