472 Mr. J. J. Lonsdale on the Ionization 



negatives are also absent. In these cases the saturation 

 curves show no peculiarities. 



At the heights 14*8 and 21*5 voltages of 600 were placed 

 on both electrodes, but no current could be observed on the 

 last electrode. This shows that at these heights no doublets 

 are formed. At a height o£ 6 cms. the mercury struck the 

 plate without breaking into drops and no ions are produced. 

 If the mercury is forced by pressure from the dropper, there 

 is no ionization produced unless the mercury forms visible 

 drops before striking the plate. 



Professor J. J. Thomson has asked whether ions are first 

 produced by splitting doublets, or are ions first produced and 

 then doublets formed by the combination of positive and 

 negative ions. These results at the lower heights show that 

 ions are produced by dropping mercury without accom- 

 panying doublets. At greater heights both doublets and 

 ions are produced. As we get the ions without doublets in 

 certain cases it would seem that something more than ions is 

 necessary to produce doublets. 



With a view to further information on the subject of 

 doublets at atmospheric pressure, the ionization produced by 

 heating aluminium phosphate and lime was examined by the 

 same apparatus. The salt to be heated was placed on a thin 

 piece of platinum-foil in a wide glass tube and then heated 

 electrically to a bright white heat. Air filtered by cotton- 

 wool was drawn over the heated salt into the apparatus. 

 The curves giving the relation between the current and the 

 voltage shown on fig. 2, are the currents from aluminium 

 phosphate, C and D, and from lime, E and F. It will be 

 seen that there is a distinct kink in each at about the same 

 voltages as the mercury curve, and the saturation voltage of 

 the second part is the same as the saturation voltage of the 



If the saturation curve be examined 

 in the case of aluminium phosphate, 

 the current does not vary by more 

 than four divisions for voltages from 

 314 to 656. Yet if a voltage above 

 300 is put on the first electrode, and 

 the current examined on the second, it 

 is seen to be larger than the four divi- 

 sions difference observed in the current 

 on the first, from the following numbers. 

 The first three lines refer to lime and 

 the last to aluminium phosphate. 



negatives. 





V. 



C. 



314 



130 



352 



130 



390 



130 



432 



130 



474 



128 



516 



130 



558 



126 



flUO 



130 



656 



130 



