MR. J. MUIR ON THE RECOVERY OF IRON FROM OVERSTRAIN. 



25 



Effect on Recovery of Temperatures below 100 C. 



Diagram No. VIII. , which is in two parts, gives the complete history of a 

 specimen which was allowed to recover its elasticity at various temperatures, after 

 having been overstrained. It shows, among other things, the very considerable 

 hastening produced in the process of recovery from overstrain by even such a moderate 

 temperature as 50 C. (120 Fahr.). A lengthy description of this diagram need not 

 be given, as the side-notes accompanying the diagram give all necessary details. The 

 tables which follow give most of the readings from which the curves of this diagram 

 have been plotted. The material employed differed slightly from that considered 

 last, particularly as regards the position and character of the yield-point ; it resembled 

 more closely, perhaps, the material of Diagram III. 



Diagram No. VIII. (First Part). {Recovery at 50 C., &c.) 



Extensions - diminished aa explained on page le. 

 Scaie : - i unit jgftj of An inch, f < t 



Curve No. 1. Primary last. 



.. .. 2. 30 minutes after No. 1 . 

 3. After 5 minutes at 50 C. 



4. 15 more at 50 C. 

 5. 17 hours at noiniitl 



ture (say 13 C.). 

 6. After 15 minutes at 50 C. 



Curve No. 7. After 5 minutes at 95 C. 



8. 3 days after No. 7. 



9. 20 minutes after No. 8. 



10. 4 hours after No. 8. 



11. After 15 minutes at 50 C. 



12.- 15 70 C. 



, 13. 5 95 C. 



A comparison of the distances at the top between Curves 3, 4, 5, and 6, strikingly 



indicates the large effect of a small increase in the temperature of the restoring bath. 



The distance between 3 and 4 (after subtracting ^th of a unit for change of origin), 



I units, may be taken as a measure of the recovery due to 15 minutes 



\i|.. c\< in. A. i: 



