DOC.

13

ELASTIC BEHAVIOR AND SPECIFIC HEAT

335

Substance A.104

Substance

X

.

104

Aluminum

45

Palladium

58

Copper

53

Platinum

66

Silver

73

Cadmium

115

Gold

79

Tin

102

Nickel 45

Lead

135

Iron

46

Bismuth

168

According

to

the

theory

of

specific

heats derived from Planck's radiation

theory,

specific

heat

is

supposed

to decline

as one approaches

absolute

zero according

to

the

following

law:

(

a

\

2

T

C

=

'6

H

[13]

where

C

denotes the

specific

molar heat and

it has

been

stipulated

that

hV

_

h.c

T

=a

=

EX

Here h and

k

are

the

constants

of

Planck's

radiation

formula.

Thus, one

can

use

the

[14]

behavior of

specific

heats

to

determine

X

for

a

second

time.

Among

the

substances

listed

above,

silver

is

the

only one

to have

had

its

specific

heat

at low

temperatures

determined

with

adequate

accuracy.

Nernst5

found for

silver

that

a

=

162,

which

yields

X.

104

=

90,

while

we

calculated

from

the

constants

of

elasticity

that

X

.

104

=

73.

This

close

agreement

is

really surprising.

A

still

more

exact test

of Sutherland's

conception

is

likely

to

be realized

only by

perfecting

the molecular

theory

of

solids.

(Received

on

30

November

1910)

5

Cf. W. Nernst, Bulletin des Seances de la Societe

franc.

de

Phys.

(1910):

19-48.

[15]