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Dr. R. W. Boyle on the Behaviour of 



The ordinates represent ionization current and the abscissae 

 the corresponding temperatures. The three curves, A, B, and 

 C, represent three widely different quantities of emanation, 

 which correspondingly required three measuring devices 

 differing widely in sensitiveness. The scales o£ ordinates 

 are therefore very unequal : scale of C > scale of B > scale 

 of A. 



In Table I. are given the experimental details concerning 

 the curves shown in fig. 2. The " Partial Pressures of 

 Emanation" are calculated — assuming Boyle's law to hold 

 approximately — from the fact that the equilibrium amount 

 of emanation of 1 gm. of radium has a volume of O'b* cub. mm. 

 at N.T.P. These pressures are included merely to give an 

 idea of the extreme tenuities of the emanation before or after 

 condensation. (The abbreviation " m.r.e " means the amount 

 of emanation in radioactive equilibrium with the stated number 

 of milligrams of radium element.) 



Table I. 



(1) 



Curve. 



(2) 

 Quantity of 

 Emanation. 



(3) 

 Vol. of 

 Tube. 



(4) 



Partial Pressure 



of Emanation. 



(5) 

 Measuring Device. 



A 



B 



C 



78 m.r.e. 

 0-30 „ 



o-oi „ 



0*6 c.c. 

 10 „ 



2-3 „ 



6xl0~ 2 mm. Eg. 

 1-5X10" 3 „ 



2xl0 -6 „ 



flOO mm. Hg. 

 Galvanometer \ pressure in ioni- 

 [ zation chamber. 



f Only a few mm. 



Electroscope J ?8: P ressur £ in 

 1 ; ionization cham- 



[ber. 



f 760 mm. Hg. 



Electroscope ^ pressure in ioni- 

 [ zation chamber. 



The general form of the curve consists of three parts. 

 First there is an initial, flat, or nearly flat, portion ; then a 

 steep portion rising from the temperature axis : and then a 

 bend towards the temperature axis, after which the curve 

 continues to rise but much less markedly. The last portion 

 extends much further than is shown in the diagram. As an 

 example the following table shows the readings in an experi- 

 ment where the galvanometer was used. 



