DOC. 12 THERMODYNAMIC

DEDUCTION

293

Published

in

Journal de

physique 3

(1913):

277-282. Lecture delivered

at

a

meeting

of the

Societe

francaise

de

physique,

Paris, 27

March

1913, published

April

1913.

[1]This

paper

summarizes results earlier derived

in

Einstein

1912b

(Doc. 2)

and

Einstein

1912f

(Doc.

5). In

a

contemporary

letter Einstein

wrote:

"Tomorrow

I must

go

to Paris

to give

a

lecture

in

French

at the

Sorbonne. Isn't that

daring?

Keep

your

fingers

crossed

on

Thursday

morning,

because then

the

miracle

will

take

place" ("Morgen

muss

ich

nach

Paris,

um

in

der

Sorbonne einen französischen

Vortrag

zu

halten.

Ist das

nicht kühn? Halte mir

also

am

Don-

nerstag Vormittag

freundlich den

Daumen;

denn dann

wird das

Mirakel stattfinden."

See Ein-

stein

to

Elsa

Löwenthal, 23

March

1913

[Vol. 5,

Doc.

434]).

For Einstein's

happy

memories

of his

trip

to Paris,

see

Einstein

to

Marie

Curie,

3 April

1913

(Vol. 5,

Doc. 435), and

Einstein

to

Jean

Perrin, 4

April

1913

(Vol. 5,

Doc. 437).

[2]See

Einstein 1905i

(Vol.

2,

Doc.

14), §9,

for Einstein's

first

application

of

the

quantum

hypothesis

to

photochemical processes.

See the

editorial

note,

"Einstein

on

the

Law of

Pho-

tochemical

Equivalence,"

pp.

109-113,

for

a

brief review of Einstein's work

on

photochemistry.

[3]In

Einstein 1912b

(Doc.

2) only an

infinitely

small

frequency

domain

was

assumed

to be

photochemically

effective; in

Einstein

1912f

(Doc. 5)

Einstein

generalized

his

approach to

a

finite

frequency

range.

[4]The

first,

the second,

and

the

fourth of

the

following

five

assumptions are explicitly

stated

in

Einstein 1912b

(Doc. 2), pp.

833-834; the

others

are

implicitly

assumed.

[5]See

Einstein

1912b

(Doc. 2), pp.

834-844, and, in

particular,

Einstein

1912f

(Doc. 5),

pp.

882-884,

for

Einstein's earlier discussion of what

he

there called

"improper"

("außergewöhnliches") thermodynamic equilibrium.

[6]Einstein had earlier denoted

the

energy

absorbed

by a

mole

as

Ne

(see

Einstein 1912b

[Doc. 2], p. 835).

[7]The numerator

on

the

right-hand

side

of

the

equation

should

be

p.

[8]Equation

(c)

is the

equation

in the

preceding

line.

[9]"l'equation

(2)"

should

be

"l'hypothese

2°."

[10]See

Einstein 1905i

(Vol.

2,

Doc.

14),

§9,

and Stark

1908a,

p.

893; see

also Stark

1912

for Stark's claim

to

priority

on

this derivation, and

Einstein

1912g

(Doc. 6)

for Einstein's

response.

[11]This

was

earlier established

in

Einstein

1912f

(Doc. 5).

[12]For

a

brief discussion of

subsequent experimental

work

on

the law

of

photochemical

equivalence

and Einstein's continued interest

in the matter,

see

the

editorial

note,

"Einstein

on

the

Law of Photochemical

Equivalence,"

pp.

112-113.