Various Gases by the a. Particles of Radium. 337 



The same result shows that, although ions are very apt to be 

 drawn through a gauze by a strong field on one side, yet in 

 this case nothing of the sort takes place. To prevent it, a 

 second gauze has been placed 3 mm. below the first, and 

 earthed, so that there are strong, equally-balanced fields on 

 both sides of the latter. 



Fist 2. 



T 







C 2 H S C\ 

 A 50 volts 

 8 \SQ - 

 C 300 •• 

 D 500 - 



Putz gas. 

 Co 3 m m 





3 cm 













C.KfQ 





A 



\ ^ 



I *.Y °) 







3 





6 



9 



A thin uniform metal sheet might replace the gauze, but 

 unless it were very thin it would cut off more of the range 

 than can generally be spared ; and if it were thin it would be 

 liable to flexure by the powerful electric forces, so that the 

 depth of the ionization-chamber might become indeterminate. 



We must now consider the assumption that the area of 

 the ionization curve may be represented by the product of the 

 coordinates III as already defined. This is really equivalent 

 to the supposition that the ionization resulting from the 

 expenditure of a quantity of energy Be by the a particle is 

 equal to kf(v)8e, where f(v) is a function of the velocity of 

 the particle and h is a constant, depending on the nature of 

 the gas molecule. It implies in the first place that the area 

 of the ionization curve in any gas is not dependent on pressure 

 and temperature, and that, if the form of the curve is altered 

 by a variation of these conditions, it is only in so far that all 

 the ordinates are multiplied by some factor, and all the 

 abscissae divided by the same factor. It implies, in the second 

 place, that the ionization curve of one gas can be made to 

 coincide with the curve of any other gas, by multiplying all 

 the ordinates by some factor, and all the abscissa? by some 

 other factor. Let us examine the evidence in favour of these 

 statements. 



If the hvpo-thesis is true, RI must be independent of pressure 

 PHI. Mag. S. 6. Vol. 13. No. 75. March 1907. 2 B 



