1306 
emee, esmee en er 4 Se LE 
We introduce this into the expression for the energy and determine 
the part of the second degree with respect to the quantities e. As 
e, etc. represent the deformations from the strained condition (e), 
the coefficients of the invariants /',? and /', will give the new 
values of A and 5. We find 
A=A+(9C + 2D)e 
B=B+(3D+E)e. 
Now when we introduce these values for A’ and #4’ into the 
expression for the thermal pressure and when we add to it the 
elastic tension at the absolute zero, we find for the total tension 
in the case of equipartition 
9C42D 3D+E 
S—(6A+2B) e+(27C-+9D LE) et | 3 
(6A4+2B)e+(27C4+9D +B) -( tee )e 8 
(9C+2D)? (3D4 EB)? | ( 
Ti AR 9 B? at ; | 
In this « is the total energy which is proportional to 7. Thus the 
equation of state for changes in which the solid body remains 
isotropic has been found. 
dS 
To find the modulus of compression we determine 7a: for this 
; aoe 
we find 
„_64+2B si Bie ee (a 2 wees ‘i 
3 3 54 A? 27 B? 
The factor e¢ now still depends on the temperature; to find this 
factor we can apply (3), where the last term may be neglected 
as we will confine ourselves to a linear expression in ¢. The e can 
then be found by considering the expansion at zero pressure. When 
we put in (3) S=O we find : 
ee SD+E ) 
€ 
184 9B 
GEE 6A--2B 
6A+2B (27C4+9D+E/9C+2D  3D+E 
in ice. Nr lea ames il L8A ae 2 
(9C-L2D)? (83D +E)? | (°) 
BAE es ore 
Easily the form of the equation of state can be indicated in the 
case that the quantum-theory is introduced. We will confine our- 
selves to the case of the temperatures being so low that the upper 
