Vol. 6, 1920 
PHYSICS: F. C. HOYT 
641 
weaker than 73 in tungsten. In the case of both 185 and 72 we are deaUng 
with Hnes which he near the absorption hmits, and as there is some evi- 
dence to show a progressive shift from element to element of the absorp- 
tion limits relative to /Ss and 72 which would bring the absorption limits 
on opposite sides of these two lines in platinum and tungsten, this may 
account for the difference in intensity here. 
Another difference in intensity occurs in the case of (34, which is stronger 
in platinum than it is in tungsten, but we can ascribe it to a different cause. 
Noticing that (3^ which is between jSi and (3^ in tungsten is apparently 
absent in platinum, and that if and ^7 in tungsten were to stay at a 
constant wave-length interval from ^3 and ^2 respectively, they would 
nearly coincide in platinum, we can think of (3^ as in reality composed of 
these two lines. Since ^3 and ^4, belong together in L3 and ^2 and ^7 in 
Li, we would expect this wave-length interval to remain constant. 
Wave-lengths of the tungsten and platinum lines in the L-series are 
given in table I. Siegbahn calls the line at 1.2031 but this puts it out of 
TABLE I 
1.499 
1.313 
1.323 
1.120 
1.101 
1.098 
1.142 
1.072 
1.080 
Tungsten 
1 . 67505 
1.47348 
1.48452 
1.27917 
1.24191 
1.26000 
1 . 29874 
1.2031 
1.2118 
1.2871 
1 . 2205 
1.202 
PLATINUM 
1.242 
0.958 
0.933 
0.929 
0.900 
0.988 
TUNGSTEN 
1.4177 
1 . 09553 
1.06584 
1 . 05965 
1 . 02647 
1 . 1284 
1.079* 
1.072 
1.044* 
*Observed by Overn only. 
line with (3^ in other elements. The wave-length interval from ^2 to /?5 
is quite constant from element to element, and if it is not to be far off 
here, we would have to take the line at 1.2118 A as 185. 
Assignment of the Lines to Sub-Series. — The existence in platinum of 
the three series Li, L2, and L3 with critical potentials near the quantum 
potentials of 185, 72 and 74 respectively was shown by Webster and Clark ^ 
and Webster. 2 The stronger lines were measured directly by ionization 
methods, and the weaker ones were classified by means of constant voltage 
photographs. The following lines have been definitely assigned, by 
measurements on platinum alone : 
Li I, a2, ai, ^2, i^e, (3^ 
L2 7], /?2, Ti 
L3 74 
