424 
ou the assumptions here made, expressed in terms of the normal 
volume as unit, dwn, = 0.692. 10 2 This value, which can also be 
regarded as to be obtained by extrapolation to very high temperatures, 
is markedly smaller than the value obtained above on the assumption 
that ay and dy may be regarded as constant over a small region of 
temperature, and it is also much smaller than that given by BRAAK, 
Diss. p. 82 and 83. We shall return to the variation of bw with 
the temperature when we come to consider the viscosity. 
From bwNe we obtain the diameter of the molecule using the 
relation 
4 
8 
b WN ANoog On == N. re a je : - F (6) 
~ 
L 
In this @) = 22413 |em*.]*) is the theoretical normal volume of 
the gram moleenle, and V = 6,85.10°**) is the AvoGapro number. 
We find 
6 = 223 10> femke 
From the values of v and o we further obtain the moment of 
the doublet 
me = 4,96.10—!" [electrostatic unit. em. |. 
Assuming that each pole bears a charge equal to that of a single 
electron, the distance between the poles should be 1,17.10—-° em.®, 
that is, about one twentieth of the diameter of a molecule; within 
the interior of a molecule there is therefore plenty of room for such 
a doublet. At the temperatures here considered the mean speeds of 
rotation assumed by the molecules are such that the electromagnetic 
force exerted by the molecules upon each other need not be taken 
into account, and this confirms the assumption previously made 
1) Cf. Suppl. N’. 23, note 23, and “Kinheiten” a. 
2) Taken from PerrIN's researches; cf. Suppl. N°. 23, note 173. 
3) Prom the energy required to ionise the gas RutTHERFORD and Mc KLING, 
Physik. ZS. 2 (1900), p 53, obtained the same order of magnitude. So, too, did 
ReinGaNuM, Physik. ZS. 2 (1900), p. 241, Ann. d. Phys. (4) 10 (1903), p. 334, 
and loc. cit. p. 417 note 1, from the dependence of viscosity upon temperature 
(cf. $6), from the tensile strength of metals, and from the latent heats of vapori- 
sation of liquids, while the same order of magnitude for the moment of the mole- 
cule was obtained by Desie, Physik. ZS. 13 (1912), p. 97, from the variation 
with temperature of the dielectric constants of certain liquids. 
