276 Mr. K A. Kent on the Zeeman Effect. 



screw was exceedingly accurate, used to measure the Zeeman 

 separation. 



Briefly the results of the investigation are as follows : — 



1. The separation of the outer components of the zinc lines 

 4680-38, 4722-26, 4810*71 is not proportional to the strength 

 of field for values of the latter from 26,000 to 33,000 c.G.s. 

 units ; that is, Reese's results for zinc are confirmed and 

 extended. 



2. Further, for iron lines chosen somewhat at random the 

 same is true, and the lines which, in the ordinary iron spec- 

 trum, are " nebulous " in character show the least increase 

 in Zeeman separation as the field is increased in strength ; 

 or, in other words, the curve plotted between strength of field 

 " H/' and resulting separation " AX," shows the greatest 

 droop. 



3. Hence it follows that Becquerel and Deslandres *, who 

 used a field of 35,000 c.G.s. units, were unjustified in their 

 attempt to discover in the lines of the iron spectrum a law 

 governing the separation. No such law as that proposed by 

 them is apparent from measurements made on my plates of 

 80 lines which appeared in good form for measurement. 



4. As to the pressure shift for iron : — In the spectrum of 

 this metal 34 lines were investigated with great care. 26 

 show both large pressure shift and large separation, or small 

 pressure shift and small separation ; while 8 show either large 

 pressure shift and small separation, or small pressure shift 

 and large separation. Thus it cannot be said that, if a line 

 show large pressure shift, it will show large separation ; or, 

 if small pressure shift, small separation. 



5. Nickel and cobalt were investigated. No law governing 

 the separation is apparent. 



6. Preston's law that -^ is constant for homologous lines 



of Kayser and Runge's spectroscopic series was extended. 

 In the expression given, " AX" represents the Zeeman 

 separation, th X " the wave-length, and " H n the field strength. 

 Preston deduced this law from measurements upon the lines 

 in the 2nd subordinate series of cadmium and magnesium, 

 whose wave-lengths are given by putting " n " equal to 3 in 

 Kayser and Runge's formula : — 



\- 1 = A + Bn~ 2 -{-Cn-' 



where "V ? is the wave-length, "A," " B," and "C" are 



constants, and " n " has integer values 3, 4, 5, &c. The lines 



* Comptes fiendus, No. 129, pp. 18-24 (1898). 



