304 
at the surface of the bath would be one of from 7,—=26° K. to 7,=15°K. 
With a-==a,7; 
7 C 
Pe ee 5 
(= ——— al = ——_ —, 
V273 os ak‘ dt 6) 
(1) now gives 
1 | 
for the first portion TT, (HP Nr Vve een 
: À 1 
and for the third portion A AChE (PSP aen = ee 
el Ant 
while the substitution of 
SURE a nr eee 
gives 
pst — p,t = AAa, ky, C2 [(Fr), —(FD)] OD 
in which 
B 5 C(2m—-3nC) 
Re ga eas 
tg'a + (Ll — 2mC + 3nC’) 
ig’a „tga, We 
Te — — ens 
(5 ee 
so that p, and p, can be expressed in terms of p, and p,. From 
(4), (5), (7) it is seen that for a case such as that discussed in $ 3 
for which 7, =15°K. and 7, = 295°K, p, does not differ appreciably 
from p,, so that one need not be very particular about the lower” 
limit in the integral of (7) and (8), and the small jump in the tempe- 
rature is of no influence within the limits of accuracy desired; this 
indeed is obvious if one considers that the gas flows about 
20 times more slowly in the cold portion while the viscosity is also 
about as many times smaller. 
With the temperature function now obtained for the interchange 
of pressure in a gas of known C,n, and a, through a capillary of 
radius Zè, and for a given temperature distribution, we obtain 
dm, ah* 
SS ee A: a “ta Gh he eo 
= age PP) 0) 
ER: 
in which m, is the mass of gas in the volumenometer, and 
IE Ln, (F7,—F7,) + Mn. 7, + Na, 
where the quantities Z, M and N follow at once from (4), (5) and (7). 
The first member of the expression for A refers to the portion of 
the capillary in which the fall of temperature occurs, and the second 
