on the Elasticity of certain Metals. 363 
where the numbers of the second column relate to the second 
definition of the modulus of elasticity. 
f the variation in elasticity is compared with the influence 
exercised by the temperature on other properties of bodies it 
will be remarked that it is much greater than the cubical dila- 
wich as well as the variations of refraction. It is of about 
the same order as the variation of the permanent ee 
caused by the temperature, as well as that of specific hea he 
increase of the galvanic resistance on the other hand is ; much 
greater 
It results further from the sign of the quadratic term that 
the variation of elasticity for all three metals is the most rapid 
in the higher temperatures. While, however, the increase for 
iron is almost imperceptible, and is ‘also v very ‘small for copper, 
it is quite considerable for brass. The decrease for 1° is for 
At 0°. At 50°. At 100°. 
Tron, 0°0447 00459: 0°0472 per cent. 
Copper, 0°0520 0°0548 0°0576 
Brass, 0°0428 0°0564 00699 =“ 
It will be observed that the differences in the variation of 
the coefficient of elasticity for the three metals investigated, 
are in the order of the height of their melting poi 
The results of these investigations show no trace at all of 
the remarkable phenomenon of a maximum, alluded to at the 
Deginning of this article, which would seem to be indicated f 
on by the investigations of Wertheim. If, therefore, different 
parse of iron do not manifest a totall different behavior, or 
if the modulus of the longitudinal elasticity does not undergo 
a very different change in consequence of temperature from 
that of the torsional elasticity, this anomaly must be accounted 
for by the imperfect method of observation employed by Wer- 
theim. This supposition is confirmed further by the observa- 
tie of Kupffer (see below), as well as by a very simple experi- 
ment, If, namely, two tuning forks are in vibration, and one 
of them is heated, the number of vibrations changes in the 
manner demanded ‘by the assumption of a decrease of elasticity 
for i greeny temperatures 
It is to be remarked here that Wertheim’s calculation of the 
— oh er by condensation during vibration, loses thus all 
ue.* 
1 lsrotion of Kup er. +—These investigations appear 
be h less known than they deserve, for they 
contiga an uch Be and sich material for practical u 
Kupifer’s Ghearbhtiie are in general on bars vibrating peed 
* Pogg. Ann., Bd. 11, S. 32. 
+ Mem. de l’Acad. de St. Petersb. 1856, 6 ser. T. vi, p. 400. 
