276 EXCITED RADIO-ACTIVITY [cH. 
decayed at the normal rate, 7.e. the activity fell to half value in 
about 11 hours. 
Experiments were also made on the solubility of emanation X 
in different substances. A platinum plate was made active and 
then placed in different solutions, and the decrease of the activity 
observed. In addition to the acids already mentioned, a large 
number of substances were found to dissolve the emanation X to 
some extent. The active matter was however not dissolved to an 
appreciable extent in ether or alcohol. Many substances became 
active if added to the active solution of emanation X and then 
precipitated. For example, an active solution of hydrochloric acid 
was obtained by dissolving the emanation X from an active 
platinum wire. Barium chloride was then added and precipitated 
as sulphate. The precipitate was strongly active, thus suggesting 
that the emanation X was carried down by the barium. 
179. Electrolysis of solutions. Dorn showed that, if solu- 
tions of radiferous barium chloride were electrolysed, both electrodes 
became temporarily active, but the anode to a greater degree than 
the cathode. F. von Lerch (loc. cit.) has made a detailed examina- 
tion of the action of electrolysis on an active solution of emanation 
X of thorium. The active matter was dissolved off an active 
platinum plate by hydrochloric acid and then electrolysed between 
platinum electrodes. The cathode was very active, but there was 
no trace of activity on the anode. The cathode lost its activity at 
arate much faster than the normal. With an amalgamated zinc. 
cathode on the other hand, the rate of decay was normal. When 
an active solution of hydrochloric acid was electrolysed with an 
electromotive force smaller than that required to decompose water, 
the platinum became active and the activity decayed to half value 
in 4:75 hours while the normal fall is to half value in 11 hours. 
These results point to the conclusion that the matter emanation X 
is complex and consists of two parts which have different rates of 
decay of activity, and can be separated by electrolysis. 
Under special conditions it was found possible to make the 
anode active. This was the case if the anion attached itself to 
the anode. For example, if an active hydrochloric solution was 
electrolysed with a silver anode, the chloride of silver formed was 
