182 Mr. H. Moore on the Ionization in Carbon- 



mixtures in order to produce the observed ionizations, it 

 being assumed for this purpose that the ionization due to 

 X-rays is produced by the ejected corpuscles. The results 

 obtained suggested that the true " atomic " phenomenon 

 might be the amount of corpuscular radiation liberated, the 

 final ionizations depending on the number of* ions produced 

 in the various vapours by the ejected corpuscles. 



It was impossible to obtain data for all the vapours 

 used, and therefore a fresh series of experiments had to be 

 undertaken to obtain the required factors. These experi- 

 ments were carried out on the mixtures themselves, the 

 object being to find what ratio exists between the ionization 

 produced in air to that produced in each mixture when equal 

 quantities of corpuscular radiation are absorbed in each. By 

 this means the amount of liberated corpuscular radiation 

 corresponding to any observed ionization can be determined 

 for each mixture. The direct determination of this factor 

 for each mixture obviates any errors which might creep into 

 its calculation (from Kleeman's numbers) based on a density 

 absorption law, a law which is possibly not universally 

 obeyed — hydrogen being a noteworthy exception. 



In this second type of experiment, a short wide chamber 

 was used, through which the homogeneous X-radiation from 

 tin was passed. A reversible lining allowed two kinds of 

 experiments to be made, one without, the other with corpus- 

 cular radiation,, The lining consisted of thin card coated 

 with gold-leaf on one side only. It was used with the gold 

 outwards at first, when the amount of corpuscular radiation 

 entering the chamber would be small ; then, during the 

 second kind of experiment it was reversed so that the gold 

 was turned inwards, thus introducing a large number of cor- 

 puscles into the mixture. The X-radiation, having to pass 

 through the same sheets of material in both cases, would be 

 of the same intensity in the gaseous mixture, and the ioniza- 

 tion due to the X-rays absorbed by the mixture would be 

 identical in the two experiments. By deducting the ioniza- 

 tion with the gold outwards from that with the gold inwards, 

 the ionization produced in the mixture by the corpuscular 

 radiation from the gold is given. A similar pair of experi- 

 ments carried out with air instead of the mixture gives the 

 ionization produced in air by the liberation of an equal 

 amount of corpuscular radiation. By this method the 

 required factors were obtained, experiments being also 

 made with hydrogen alone to determine the factor for 

 hydrogen : the factors obtained are given in column II. 

 Table II. 



