10 



Proceedings of the Royal Irish Academy. 



There is, of course, uo reason to expect that the iouisatiou produced by 

 splashing and that produced by a ditterent method of breaking up water 

 should be identical. But apart from any apparent want of harmony between 

 these results, it was felt that there was need for a more detailed examination 

 of this type of ionisation. 



Apparatus and Method of Expcnment. 



The arrangement of apparatus is shown in fig. 1. The spraying apparatus 

 — a metal scent-spray fitted to a large bottle — is placed inside a cylindrical 

 metal vessel. Connected to this vessel is the " measiu-ing-cylinder." It consists 

 of a metal cylinder with a coaxial cylindrical electrode. The latter is insulated 

 from the cylinder, and connected to a Dolezalek electrometer. The cylinder 

 is connected to a battery of cells. The insulation of the electrode is protected 



Zai-th 



To ^Oason.tlrr 



^ 



,ripn^ 



on 



TaI 



Fig. 1. 



against drops of water by a specially long guard-cylinder connected to 

 earth. In the earlier experiments insulating material (^^) was introduced 

 between the measuring-cylinder and the spraying-chamber. But afterwards 

 in working with the more mobile ions it was found con^■enient to establish 

 metallic connexion, so that the two vessels were at the same potential. 

 This pi-evented any ions being held back by an adverse field from entering the 

 cylinder. The measuiing-cylinder was connected by tubing to a large 

 gasometer, so that air could be drawn from the spraying-chamber (which 

 had openings at B and C) at any desired rate. In the first experiments the 

 sprayer was driven with oxygen at a pressure of about 100 cms. of water. 

 Most of the experiments, however, were made with air at a pressure of about 

 20 cms. of mercury. Xo difl'erence in the nature of the ionisation was found. 

 The results got by the two methods have not, therefore, been specially 

 distintfuished. As to the magnitude of the etl'ect, no proper comparison can 

 be made, as the sprayers were difl'erent in the two cases. 



