242 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1910. 



This energy may easily be computed as follows: As will appear 



later the radius of the drop was in this case 0.000197 centimeter. 



Furthermore, the value of the elementary electrical charge obtained 



as a mean of all of our observations is 4.891 X10~ 10 - Hence the 



energy required to drive an ion carrying a unit charge up to the 



surface of a charged sphere of radius r, carrying 16 elementary 



charges, is 



16e* 16 X (4.8 91 X10- 10 ) 2 ., 95xl0 - M ercTS 

 ~~ 6360197 -1-95X10 ergs. 



Now the kinetic energy of agitation of a molecule as deduced 

 from the value of e herewith obtained, and the kinetic theory equa- 

 tion, p=$nmu 2 , is 5.75 X10~ 14 ergs. According to the Maxwell- 

 Boltzmann law, which doubtless holds in gases, this should also be 

 the kinetic energy of agitation of an ion. It will be seen that the 

 value of this energy is approximately three times that required to 

 push a single ion up to the surface of the drop in question. If, then, 

 it were possible to load up a drop with negative electricity until the 

 potential energy of its charge were about three times as great as 

 that computed above for this drop, then the phenomenon here ob- 

 served, of the catching of new negative ions by such a negatively 

 charged drop, should not take place, save in the exceptional case 

 in which an ion might acquire an energy of agitation considerably 

 larger than the mean value. Now, as a matter of fact, it was regu- 

 larly observed that the heavily charged drops had a very much 

 smaller tendency to pick up new negative ions than the more lightly 

 charged drops, and in one instance tee watched for four hours 

 another negatively charged drop of radius 0.000658 centimeter, 

 which carried charges varying from 126 to 150 elementary units, arid 

 which therefore had a potential energy of charge {computed as above 

 on the assumption of uniform distribution) varying from ^XlO' 14 

 to 5.47X10 -14 , and in all that time this drop picked up but one single 

 negative ion, and that despite the fact that the ionization was sev- 

 eral times more intense than in the case of the drop of Table I. 

 This is direct proof independent of all theory that the order of mag- 

 nitude of the kinetic energy of agitation of a molecule is 5X10" 1 *, 

 as the kinetic theory demands. 



THE QUESTION OF VALENCY IN GASEOUS IONIZATION. 



The correctness of assertion 5 in the case of the ionization existing 

 in the observing chamber at the time at which the data in Table I 

 were taken is directly proved by the readings shown in that table, 

 since the great majority of the changes recorded in column 4 corre- 

 spond to the addition or subtraction of one single elementary charge. 

 There are, however, some changes which correspond to the addition 

 or subtraction of two or three times this amount and which therefore 

 seem at first sight to indicate the existence of multiply-charged ions. 



