Diffusion of Hydrogen through Hot Platinum. Ty 
proportional to p* in equation (1) and testing the experimental 
numbers by the formula so obtained. To compare with 
previous results we divide m by the area (8) of the internal 
surface of the platinum tube and obtain instead of (1) 
Q=2kpir[ Vo + o(c—2ay)], 
where k=1/RS. It in this we put 
Q=Ap?=A (2p [¢—a,])* 
and integrate, we obtain 
me ETN?) i Wits ; 
i (,-) = B—2(Vo—oc)(c—2)?—40(c—a)?, , (3a) 
where B is an integration constant. Asa matter of fact B 
determines the time required for all the hydrogen to escape, 
which is given by the equation T=(2¢)#kB/A. 
The accuracy of formula (3) has been tested by means of 
three series of numbers corresponding to different tempe- 
ratures. The temperature in the first series—those given in 
Table I1].—was 1158°C. The first column in the Tables 
(IIL., IV., and V.) contains the value of c—#(=y), and the 
second that of 2(V,—oc)y2+4oy:. The third column was 
obtained by subtracting two of the numbers in column II. 
from one another and dividing by the corresponding integral 
of time. In order to obtain as large a difference as possible 
the sixth row in column II. was subtracted from the first, 
the seventh from the second, and so on. The resulting 
values are proportional to the value of A, and their constancy 
therefore forms one test of the square-root pressure law. The 
fourth column was obtained by multiplying the mean value 
of the numbers in the third column by ¢. Addition of corre- 
sponding numbers in the second and fourth columns should 
then give independent values of B. The values of B thus 
found are exhibited in column V., and their constancy forms 
a second test of the square-root law. 
TaBLeE III. 
|. | ] 
| a II. TR Oe Go ee 
| y=c—a,. | 9y? +1122. 2965t | B. 
aes hI 3352 0 335-2 
| 106 313-2 21-9 3351 
| 91 289'6 45-0 334-6 
76 264-2 69:9 3341 
61 236'2 i 97:0 333-2 
46 204-7 3:00 128:8 333°5 
3:1 164-0 3:07 166-0 330°0 
2-1 138-0 2:96 1963 3343 
15 1164 2-94 218°5 334-9 
‘9 90-2 2:90 246 336°2 
| 3 51-4 2-92 284 | 335°4 
