562 Mr Campbell, The Radioactivity of Potassium, 
Table II. 
Salt in solution 
°/o k. 2 o 
Activity 
Activity K 2 0 
k 2 co 3 
9-8 
140 
143 
33 
10-8 
16-5 
153 
33 
19-0 
26-0 
137 
33 
25-7 
31-0 
121 
33 
29-5 
38 
129 
33 
33-0 
46 
140 
KOH 
26 
31-0 
120 
kno 3 
9-8 
14-5 
148 
KI 
14-7 
20-5 
139 
K . C 2 H 3 0 2 
24-5 
30*5 
124 
„ (in 
alcohol) 8 '64 
9-9 
115 
Not only are the activities of solutions smaller than those of 
solids, but they appear to be much more variable. Successive 
measurements made on a solid always agree to two or three units: 
successive measurements on a solution often differ by twenty units 
and it is only by taking some ten or fifteen observations that 
a mean can be obtained which can be reproduced to the same 
degree of accuracy as a single observation on a solid. Many 
variations in the apparatus have been tried in order to get rid 
of this variation but none have been successful. No explanation 
can be offered at present, but the phenomenon is probably connected 
with the abnormality of the activity. 
§ 7. When rearrangement of the apparatus had failed to get 
rid of the peculiarity of solutions, a few rough experiments were 
tried on solutions of uranium. Table III shows the results. It 
Table III. 
Substance 
°lo uo 3 
Activity 
Activity U0 3 
uo 3 _ 
100 
•790 
•79 
Solution (1) 
35-6 
•278 
•78 
„ (2) 
23-4 
•196 
•84 
„ (3) 
22-5 
•182 
•82 
» (4) 
16-4 
•131 
•80 
„ (5) 
13-0 
•117 
•90 
» (6) 
10-7 
•092 
•86 
will be observed that none of the solutions show an activity less 
than that which would be expected from their content of uranium: 
the deviation is in the opposite direction to that of the potassium 
salts and is in the direction which might be expected from what 
is known of the value of \jp for /3 rays. The experiments of 
