362 



BRUSH— GENERATION OF HEAT IN STEEL. 



to have in my laboratory. Fig. 3 shows the composition of this 

 metal, which is hard and very brittle. The carbon is all combined, 

 and remains so after heating and quenching. 



An induction experiment with a large lump of the metal showed: 

 Temperature of complete loss of magnetic susceptibility 757°. 



40 60 80 100 



Hours After Harderung 

 Fig. a. 



140 



Temperature of complete recovery of magnetic susceptibility 



704°. 



Slowly heated many fragments, aggregating in weight that of the 

 usual twelve bars of steel, to 906° and quenched. 



Very moderate generation of heat followed the quenching, as 

 shown in Fig. 3, and it was much less persistent than usual, as indi- 

 cated by its small value at the end of 150 hours. Hardness was 76. 



The behavior of this specimen of steel, or white cast iron, was not 

 thought sufficiently encouraging to warrant finiher experiments 

 with it. 



For a general check on the performance of the apparatus, twelve 

 half inch round bars of Swedish charcoal iron, of the aggregate 

 weight of the steel usually employed, were slowly heated to 960° 

 and quenched. Complete loss of magnetic susceptibility had oc- 

 curred at 801°. The bars were warmed about three degrees just 

 before being placed in the calorimeter. 



There was no trace of heat generation following the quenching. 

 Indeed, the curve of cooling followed the normal cooling curve with 

 such fidelity that nowhere did they differ as much as the width of 



