1902.] produced by the midden Cooling of Metals. 



85 



copper rods. Curve A of that diagram was plotted from a tensile test 

 made with the material in the condition as supplied. Curve B shows 

 the elastic properties of the material after it had been heated to 630° C, 

 and allowed to cool slowly, while Curves C b Co, and C 3 show the effect 

 produced by quenching the copper from 500° 0., from 550° C, 

 and finally from 600° C. Specimen B showed more perfect elastic 

 behaviour for low loads than Specimen A, but large extension is shown 

 by Curve B to have occurred earlier with the annealed material. 

 Specimen C was first heated to 500° C, and quenched in cold water. 



Diag-kam No. 4. — (Mild steel under compression.) 



tons/in 2 



25 



%20 



i< 



I 



■% 



-J 







A. 

















































i 



tj 













7 











Contractions diminished hyzs§jsoo b - s of an inch forevery4 tons} 

 Sc&Lei-lUniU f an j ncn , p , / ,* of stress) 



Specimen A. — Annealed. 



„ B. — Quenched from a red heat. 



Diameter of specimens = 1*16 inches. 

 Total length = 1| inches. 

 Contraction measured on li inches. 



Curve C x was then obtained by applying and removing a load of 

 15,000 lbs. per square inch. The specimen was next quenched from 

 550° C, and Curve C 2 shows the slightly greater loss of elasticity 

 which was thus produced. Curve C 3 shows the large effect caused 

 by quenching the Speci men from 600 C. The breaking stresses 

 obtained with the three specimens were 35,300, 33,500, and 32,300 lbs. 

 per square inch of original area. These stresses were equivalent 

 to 41,600, 40,800, and 44,200 lbs. per square inch, when allowance 

 was made for the diminutions in area due to the large extensions 

 of the specimens before fracture. These corrections were made by 



VOL. LXXI. jt 



