EFFECT OF TEMPERATURE ON COPPER. 295 
enraiy J C1 
iets oe et 
| sal ttt — or] at | ef of aie 
a 4 > 
oe of 
1 
+, oa i I 
a ~ oo a o <7 
12. Summary of Results.—The results of the investigation may 
be summarized thus :—(a) The relation between the ultimate 
tensile strength and the temperature may be very closely repre- 
sented by the equation f = 32000 -21 ¢, where / is the tensile 
strength expressed in pounds per square inch, and ¢ is the temper- 
ature expressed in degrees F. (b) Temperature does not affect 
the elongation or contraction of area in any regular manner: and 
at any one temperature the variation in these two quantities is so 
great for different specimens that no particular percentage 
could be included in a specification for the supply of copper. (¢) 
The elastic limit in tension occurs at about 5,400 Ibs. per square 
inch at a temperature of 57° F.: this limit probably decreases 
rapidly with increase of temperature, but the differences in the 
behaviour of individual specimens are so great as to prevent the 
determination of the relationship between the two quantities. (d) 
The elastic limit in compression occurs at about 3,200 Ibs. per 
Square inch at a temperature of 57° F.: it decreases with increase 
of temperature, the relationship between the two being more 
regular than in the tensile tests. (e) The rate of permanent 
extension and compression increases rapidly with increase of tem- 
perature, as shown by the autographic stress-strain curves. 
