Mobility of the Positive Ion in Flames, 



'83 



at various temperatures. The temperature stated refers to 

 the mean value for that portion of the flame in which the 

 minimum gradient occurs. In the last column are given the 

 relative mobilities on the assumption that the mobility varies 

 as the square root of the temperature. 



It will be seen by comparing columns V. and VI. that at 

 the three highest temperatures given the mobility varies very 

 approximately as the square root of the temperature. This, 

 it will be shown later, denotes an ion of mass equal to that 

 of a hydrogen atom between these limits of temperature. 

 Below 1450° the mobility falls off very rapidly, until at 1150° 

 it only retains a few per cent, of its former value. Had the 

 law k — k vd persisted, the mobility at 1150° would have 

 fallen to only 77 per cent, of the highest value. It is obvious 

 that extensive clustering sets in at temperatures under 1450°. 

 By representing the results graphically (vide fig. 4), it is 



Fig. 4. 

 Variation of Mobility and Temperature, 



500 















cS 1 

























/ 



f 











,' 















V 















' 









i 









' 









J 









/ 







A 



/ 







600 900 1200 1500 1800 



Temperature absolute. 



seen that this clustering commences at about 1400°. Down 

 to 1300° ions from all metals give the same result, but at the 

 two temperatures examined below 1300° it was found that 

 the ions produced by the divalent metals had a smaller 



3F2 



