DOC.

21

MOLECULAR MOTION IN

SOLIDS

377

Experiments will

have to

decide whether

C

is independent

to

some

extent

of

the nature

of the

substance;

it will

be the task of

theory

to

modify

molecular

mechanics in such

a

way

that

it will

yield

the

law

of

specific

heats

as

well

as

the

seemingly

so

simple

law

of

thermal

conductivity.

Prague, May

1911. (Received

on

4

May 1911)

NOTE ADDED IN PROOF.

To

make

clearer the

last sections

of

§2,

let

me

add the

following.

If

p(v/v0)

denotes

a

function

that

is

to be

conceived

as

the

temporal frequency

of

the

instantaneous

frequency v,

and

j

(v0/T)

the

specific

heat of the monochromatic

structure

of

frequency

v0,

then the

specific

heat of

the

nonmonochromatic

structure

can

be

expressed

by

the formula

=

f$(vox\,J~(x)dx.T

x=o

One

arrives at

Nernst's formula

if

the function

p(x)

is

given

values

different from

zero

for the

arguments

1

and

1/2

only.