Mobility of the Positive Ion i 



Following is the list of the salts used 

 CsCl; Cs 2 C0 3 , 

 RbCl; Rb 2 C0 3 , 

 KC1 ; K 2 C0 3 , &c, see above, 

 NaCl ; Na 2 C0 3 ; NaOH, 



Li 2 S0 4 , 



BaC0 3 , 



8rC0 3 , 



Fla 



mes. 



779 



J> Monovalent metals. 



LiBr ; 



BaCl 2 ; 



SrCl 2 ; 

 CaCl 2 . 



It was found that from 1300° 

 duced ions of the same mobility 



Divalent metals. 



J 



upwards all these salts pro- 

 below 1300°, however, the 



monovalent metals led to a greater mobility. 



(4) Variation of Current ivith Temperature. 

 The saturation current in the flame fell off very rapidly 

 with the temperature, so that at low temperatures a very 

 sensitive galvanometer was required. In the earlier work a 

 d'Arsonval instrument giving 10 8 scale-divisions per ampere 

 was employed ; at low temperatures it was replaced by a 

 Nalder instrument 15 times as sensitive. On account of 

 the small distance between the electrodes (about 3 cm.) 

 saturation is closely approached with a fairly small voltage. 

 With 100 volts between the electrodes, the current generally 

 attains three parts of its saturation value. As no figures 

 connecting flame temperature with saturation current have 

 yet been published, I give below in Table I. the mean values 

 deduced from a large number of curves. No special attention 

 was paid to this branch of the work, but it was thought 

 desirable to put the results on record. The effective area of 

 the electrodes was about 2 sq. cm. j the values given are for 

 the total current. 



Table I. 

 Saturation Current and Temperature in Pure Flame. 



Temp. Abs. 



Saturation Current. 



Log. of Current. 



1150° 



35X10 -9 amp. 



54 



1220 



51 



71 



1300 



107 



103 



1370 



150 



118 



1450 



230 



136 



1700 



600 



178 



1950 



1500 



218 



