DOCS.

6,

7

FEBRUARY-MARCH

1903

11

Incompl.

semiperm.

membrane

according

to

Sutherland.[22]

Suppose

that

during

the

functioning

of

the

incompl. semip.

membrane

in

the

absence

of

counterpressure

a

certain

quantity

of the

dissolved

substance

passes through.

If the

concentration of the solution

passing

through

remains

unchanged,

then the membrane

is not semipermeable,

and

the

pressure is

0;

if

the concentration

is

0,

then the

pressure

is

equal

to

the

theoretical

osmotic

pressure.

/

\A

pressure

B

--Concentration of

the

solution

passing through

It

seems

to

me

that

it follows from

Sutherland's

conception

that the

line in

the

diagram

would be

a

straight

line from A

to B.

7.

To

Michele

Besso

[Bern] Tuesday

[17

March

1903][1]

Dear

Michele,

Thanks

for

the letter

and

card! I

ought to

have

written

so

many

letters

in recent

days-this

is

my excuse,

and it

applies

to all

of

them,

because I have not

written

a single

one.[2]

First of

all

about

the[3]

--v

=

0. If

one

interprets

p1

...

pn as

coordinates

9pv

in

an

n-dimensional

space,

then the

system

corresponds to

a

point.

e

is

the

density

of

points,

sipv are

the

components

of

the

material

flow,

and

the

above

expression

the

solenoidal condition. The condition that E

be the

only

integral

of the

equations

of

the

given

form[4] is

no

limitation,

since

I

free

myself

of it

when

I

consider

"adiabatically"

influenced

systems.[5]

Your

note

concerning

cathode radiation

seems unobjectionable

to

me.[6]

Have

you

already

calculated the absolute

size

of the

ions

under the

assumption

that

they

are

spheres

and

that

they are large

enough

to

permit

the

application

of

the

equations

of

the

hydrodynamics

of

viscous

liquids?

Given

our knowledge

of

the

absolute

size

of

electrons,

this would

certainly

be

a simple

matter.

I

would have

done

it

myself,

but

I

do

not

have

the

necessary

literature

and

the

time for

it;

you

could also

make

use

of