FOR MEASURING THE EXPANSION OF SOLIDS. 
279 
ing point of mercury, as proposed by MM. Dulong and Petit ; which agrees 
very closely with the amount employed in my first calculations, and which, de- 
ducting 62° for the mean temperature at which my experiments commenced, 
gives 600° for the interval for which the several expansions were determined. 
The first column of the following Table refers to the number of the experi- 
ment; the second to the mark of the register and the bar which was employed ; 
and the third to the amount of expansion in the same, occasioned by boiling 
mercury or 600° of temperature upon Fahrenheit’s scale. The fourth column 
exhibits the arc measured upon the scale ; and the fifth the equivalent expan- 
sion. The sixth contains the corresponding temperature ; the seventh records 
the state of the metal, which was the object of the experiment ; and in the 
eighth I have recapitulated the corresponding results of my former Essay. 
Table X. 
No. of 
Experi- 
ment. 
Mark of Re- 
gister and 
Bar. 
Expan- 
sion for 
600 °. 
Arc mea- 
sured on 
Scale. 
Expan- 
sion. 
Temperature. 
Metals observed. 
Temperature 
by former 
Pyrometer. 
7 
B 
Platinum 
.0152 
o 
5 
49 
.0508 
2005 + 65 
2070 
Copper, fusing point. 
2548 
8 
II 
Platinum 
.0159 
6 
10 
.0537 
2026 + 65 
2091 
Gold, fusing point. 
2590 
9 
III 
Iron 
.0229 
9 
2 
.0787 
2061+65 
2126 
ditto 
ditto 
12 
IV 
Platinum 
.0116 
4 
10 
.0363 
1877 + 65 
1942 
Silver, fusing point. 
2233 
13 
V 
Iron 
.0203 
7 
24 
.0645 
1906 + 65 
1971 
ditto 
ditto 
14 
I 
Platinum 
.0116 
6 
16 
.0546 
2824 + 65 
2889 
Iron, fusing point. 
3479 
17 
A 
Iron 
.0203 
2 
45 
.0239 
708 + 65 
773 
Zinc, fusing point. 
648 
18 
B 
Iron 
.0245 
4 
7 
.0358 
876 + 65 
941 
Zinc, inflaming. 
The most remarkable fact displayed by the preceding comparison is the 
beautiful accordance of the results obtained from two metals whose expan- 
sions are so different as those of platinum and iron. The temperature indi- 
cated by the latter exceeds that by the former in the instance of the fusing 
2 o 
MDCCCXXX. 
