Ionization produced by Heated Salts. 



07 Ft 



6 1 t> 



to 320 volts when ionization by collision occurred. The 

 above remarks are applicable to positive and negative 

 current-E. M. F. relations obtained at pressures of 9, 7, 3, 1, 

 and 0*4 cm. In general it was impossible to obtain, during 

 the first ten or fifteen minutes' heating, current readings 

 which were of any value in determining the saturating 

 potential. The very rapid initial rise or decay of the 

 ionization, as exhibited in the curves in fig. 3, explains 

 the difficulty. It was expedient, therefore, to determine the 

 relations between current and potential in the regions of 

 steady or slow decay with time effects. 



P = 9 cm. H 



< v . 



Table I. 



450-5° 0. 



1 div. = lxl0- 10 



ami 



Potent) a i,. 



Current. 



(Volts.) 



(Tube A.) | (TubeB.) 



1 



+ 40 



25'8 



4-6 



+80 



46-9 



11-7 



+ ]20 



64-0 



18-3 



+ 160 



80-0 



22-5 



+200 



82-5 



22-1 



+240 



85 



26-8 



-40 



22-0 



2-0 



-80 



41-5 



29 



-120 



60-3 



4.4 



-160 



70-S 



54 



-200 



700 



5-3 



-240 



732 



6-7 



The positive ionization was examined under a constant 

 pressure of 1*3 cm. and at temperatures which ranged from 

 345° C. to 465° G. 300 mgms. o£ cadmium iodide were 

 used in each case. Two sets of results are given in fig. 3 ; 

 curves 1 and 2 show the current-time relations at a tempera- 

 ture of 385° C, curves 3 and 4 at 465° C, under the 

 saturating potential of 200 volts. Curves 1 and 3 pertain to 

 the ionization effects in the salted tube A. Curves 2 and 4,. 

 obtained with the unsalted tube B, show that there can he 

 an ionization in B ivhen uncharged matter only enters it. In 

 fact the ionization in B may equal or exceed that of the 

 salted tube. The current-time relations at 415° C. showed 

 that the currents in B, initially equal to those in A, were 

 after two hours' time twice or thrice as large. The ionization 

 produced in both tubes when the temperature was below the 



