360 



BRUSH— GENERATION OF HEAT IN STEEL. 



Following the eighth quenching there was good generation of 

 heat, better than after third quenching, but differently distributed in 

 time — not so rapid at first, but much better sustained (curve not 

 plotted). This appears to confirm the third experiment. 



I cannot, thus far, offer any promising explanation of the absorp- 

 tion of heat in the fourth, fifth, sixth and seventh experiments. 



It may be seen that absorption was rapid during the first few 

 hours, and nearly (not quite) ceased at the end of 50 or 60 hours; 

 while generation was well marked up to 150 hours. In earlier ex- 

 periments generation of heat was easily detected at the end of a 

 month. 



As it seemed desirable to learn whether plain carbon steel would 

 show, like the nickel-chromium steel, generation of heat without 

 hardening, or absorption of heat when quenched at rising tempera- 



Analysis of Steel 

 Phosphonos 0.012 

 Sulphur. 0.016 

 Silicon 0.21 



Manganese 0.31 

 Carbon 1.14 



10 20 30 40 50 60 70 80 



Hours After Hardening 



Fig. 2. 



120 



140 



tures below the lower critical temperature, after annealing, the fol- 

 lowing experiments were made with the carbon steel used for the 

 first experiment described in the first paper of the series. The 

 normal cooling curve and upper curve of heat generation shown in 

 Fig. 2 are taken from that paper. 



Following is a resume of the early and recent experiments with 

 the carbon steel : 



