429 
where R is a gas constant, equal to 1.98 gram calories, for Pb a = 58, 
b = 7.8 X 10- 5 . 
In the following tables (see p. 431) the values of atornic heats 
of lead and silver at various temperatures are recorded. 
Lead (atomic heat). 
Absolute 
temp. 
Nernst's 
observed value 
Calc. from 
Einstein 
Calc. from 
Griffiths 
62° 
5.63 
5.58 
5.62 
66° 
5.68 
5.63 
5.64 
79° 
5.69 
5.75 
5.68 
Dewar’s value at about 50’ abs. = 4.96 
Silver (atomic heat). 
64° 
3.72 
3.61 
84° 
4.43 
4.44 
86° 
4.40 
4.50 
Dewar’s value at 50° abs. = 2.62. 
Though Nernst’s, Einstein’s and Griffiths’ values agree with each 
other, Dewar’s values are divergent owing to a large range of 
temperature. 
Griffiths and Griffiths have calculated the following values of 
the atomic heats at — 273° C., Al = 3.54, Fe = 0.73; Cu = 4.73, 
Zn = 4.294, Ag = 5.378, Cd = 4.95, Sn = 4.997, Pb = 4.527. 
These figures also do not agree with the statement of Dewar 
that atomic heats of elements bet ween the boiling points of liquid 
hydrogen and helium would be all very small and nearly constant. 
Evidently Dewar’s data show the mean atomic heat between his 
experimental range of temperature. 
Sinee the product of atomic weight and specific heat at the ordinary 
temperature is very nearly constant, if we plot the atomic heats at 
the ordinary temperature against the atomic weights, we shall get a 
straight line parallel to the axis representing the atomic weights. 
On the other hand by plotting the specific heats of elements at the 
ordinary temperature against their atomic weights, very nearly a 
rectangular hyperbola is obtained, since the product of specific heat 
and atomic weight is constant. 
This non-periodic curve is quite unique amongst the physical 
