GASES BY THE ACTION OF RONTGEN RAYS AND OTHER AGENTS. 
439 
§ 9. Nuclei Produced by the Discharge of Electricity from a Pointed 
Platinum Wire. 
The effect of the electric discharge from a pointed wire in altering the appearance 
of a steam-jet has been studied by many observers. 
In expansion experiments, however, no effect appears to liave been noticed other 
than the immediate removal of all dust particles or fog from the air inside the 
ajiparatus.^ To study the properties of the condensation nuclei arising from this 
source an expansion apparatus allowing of rapid expansions of large amount is, in 
fact, necessary. 
Fig. 12. 
The apparatus which I have used for experiments on this subject is shown in 
fig. 12. The cloud-vessel consisted of a glass bulb with a side tube through which 
was sealed a platinum wire, reaching well into the interior of the bulb and ending in 
a sharp point. This was connected to one terminal of a Wimshurst machine. The 
other terminal of the machine was connected to earth and to another platinum wire 
fused through the neck of the bulb, the lower part of which was filled with mercury, 
covered with distilled water. The side tube was kept dry by warming when 
necessary with a small flame. 
No condensation nuclei were produced, except when the point of the wire was 
luminous when viewed in the dark. 
* First observed by Lodge, ‘Nature,’ vol. 31, p. 26-5, 1885. 
