FOR MEASURING THE EXPANSION OF SOLIDS. 
269 
The expansion of Platinum. 
Length of Bar. 
From 32° to 212° = .00088420 X 6.5 . . . = .005747300 
From 360° to 572° = .00091827 X 6.5 . . . = .005968755 
.011716055 
From 212° to 360° = Mean of the above . . . = .005858027 
Total expansion from 32° to 572° = .017574082 
Add for the expansion from 572° to 660°, 
the temperature of boiling mercury, calculated at 
the highest rate : — 
180° : .005968755 : : 88° : .002918058 . . =.002918058 
.020492140 
Deduct expansion for 32°, the experiment with the 
pyrometer having been made at 64° .... =.001021742 
Calculated at the lowest rate : — 
180° : .005747300 : : 32° : .001021742 
Real expansion of the bar by Dulong and Petit = .019470398 
If from the real expansion thus obtained 01947 
We deduct the apparent expansion obtained by the pyrometer .01163 
The remainder .00784 
will be the expansion of the black-lead. ~ 
The expansion of Iron. 
Length of Bar. 
From 32° to 212° = .00118203 X 6.5 . . . =.007683195 
From 360° to 572° = .00146842 X 6.5 . . . = .009544730 
.017227925 
From 212° to 360° = Mean of the above . . . = .008613962 
Total expansion from 32° to 5 72° =.025841887 
Add for the expansion from 572° to 660°, 
the temperature of boiling mercury, calculated at 
the highest rate : — 
180° : .009544730 : : 88° : .004666311 . = .004666311 
.030508198 
Deduct expansion for 32°, the experiment with the 
pyrometer having commenced at 64° . . . =.001365901 
Calculated at the lowest rate : — 
180° : .007683195 : : 32° : .001365901 
Real expansion of the bar by Dulong and Petit . .029142297 
