4 



Duane — Emission of Electricity. 



7. The same amount of emanation was not used in each case, 

 so that the magnitudes of the currents in the two tables can- 

 not be compared with each other ; but it will be noticed that 

 with brass surfaces the positive current is six times as large as 

 the negative, whereas with iron surfaces it is only three times 

 as large. Thus the nature of the surfaces has a considerable 





Table I. 









Table II. 









Iron Tube and Electrode 





Brass Tube and Electrode 





Time 



+ Current 



— Current 





Time 



+ Current 



— Current 





+ Current 



in 



mm. 



mm. 



i^ sum 



in 

 min. 



mm. 



mm. 



% sum 

 C 



for 



min. 



sec. 



sec. 



sec. 



sec. 



1 potential 



11 



5-00 





1-64 



12 





2-27 







13 





1-68 





14 



10-50 





4-19 



4*30 



15 



4-72 





1-54 



16 





1-97 





4-14 



17 





1-58 





18 



9-80 





3-94 



4-05 



19 



4.43 





1-45 



20 





1-86 







21 





1-49 





22 



9-35 





3-77 





23 



4-03 





1-29 



24 





1-75 





3-59 



25 





1-43 





26 



8*85 





3-59 



3-38 



27 



3-86 





1-23 



28 





1-60 





3-31 



29 





1-39 





30 



8-33 





3-39 



3*19 



31 



3-57 





1-13 



32 





1.50 







33 





1-25 





34 



7-64 





3-08 



2-80 



35 



3-16 





0-96 



36 





1-45 







37 





1-20 





38 



7-00 





2-79 





39 



2-96 





0-90 



40 





1-39 





2-48 



41 





1-12 





42 



6-30 





2*46 





43 



2*78 





0-84 



44 





1-36 





2*08 



45 





1-10 





46 



5-82 





2*24 





47 



2-55 





0*75 



48 





1-31 







49 





1-01 





50 



544 





2-11 





51 



2'45 





0-74 



52 





1-13 







53 





0-93 





54 



5-10 





1-99 





55 



2-16 





0-63 



56 





1-10 





1-70 



57 





0*86 





58 



4*65 





1-79 





59 



1-98 





0-57 



60 





1-03 







61 





0-81 





62 



4-20 





1-62 



1-51 



69 



1-59 





0-45 



70 





0-78 







71 





0-66 





72 



3-58 





1-41 





effect on the currents, a fact that was not unexpected, as 

 undoubtedly the secondary and tertiary etc. rays from both 

 surfaces furnish carriers for the electric charges. 



8. The question whether any current is due to the ioniza- 

 tion of the residual quantity of air left between the metal 

 surfaces is an important one, and several series of experiments 



