552 



Prof. Richardson and Mr. Hulbirt on the 



Iron. 



Very erratic results were obtained with this metal and the 

 values of e\m obtained showed no tendency, so far as we have 

 been able to observe, to become constant either with lapse of 

 time or with any other conditions. This is probably to be 

 attributed to irregularities in the emission itself, as it was 

 very frequently noticed that during the experiments with 

 iron the electrometer spot did not move uniformly, but 

 was liable to jerks as though the thermionic emission was 

 ah intermittent phenomenon. Moreover, the value of the 

 fraction of the total ionization which passed through the slit 

 in any particular position was not constant, but kept varying, 

 so that it was often impossible to get the same value twice at 

 the same point. For these reasons the values obtained with 

 iron do not possess the same definiteness as in the case of 

 the preceding metals. A large number of experiments were 

 made with iron in the hope of being able to make the con- 

 ditions more definite. Two different kinds of iron were used: 

 (a) strips of Norway iron rolled from wire, (6) strips of 

 transformer iron rolled from sheet. The numbers for those 

 experiments on Norway iron which led to an estimate of ejm 

 are given in the following table: — 





Norway 



Iron. Positive Ions. 





z. 



H. 



V. 



X, 



e/m. 



•550 

 •550 

 •455 



4850 

 4850 

 4650 



304 

 223 



200 



1-40 

 1-475 



•90 



500 

 410 

 317 



Average values ... e/m=409, Corrected ... e/n 

 m/B.= 23-6, m/E 



\ 



,=650. 



= 14-8. 













that it was noted at the time that in the case of the experi- 

 ment which gave the lowest value of e\m the conditions were 

 exceptionally steady. If this number (317) were taken 

 alone we should have for the corrected values of ejm and 

 m/H the numbers 



e\m 503 



and 



ijR 19-2. 



