xx Journal of the Asiatic Society of Bengal. [N.S., XIV, 
Band Spectra. 
_ The study of the magnetic resolution of band spectra is of 
great interest, because, at one time it was thought that unlike 
line spectra they are not of electronic origin. For a very long 
time, repeated investigations failed to show the evidence ot 
the Zeeman effect in the case of individual lines of which the 
band spectra are formed. Dufour found that some of the 
bands were sensitive to the magnetic field. Fortrat has 
recently shown that the apparent absence of the Zeeman effect 
in band spectra was due to insufficient strength of the magnetic 
yed, and that when a field of 40,000 or 50,000 
all the lines. The latest work shows that the study of the 
those which do not. Among the latter, all those which have — 
been investigated up to the present time in intense fields have 
their lines slightly displaced by the field in a manner which 
varies from one series to another, but always in the same way 
for the same series. With regard to others, which show 
Zeeman effect, identical separations are found for the heads 
of any particular series. These facts show that the distribution 
into series has a true physical significance. 
Very recently Deslandres and Burson examined the spe 
Zeeman effect was observed, in addition to special displace- 
ments, and simplifications of the doublets similar to those des- 
cribed by Paschen and Back and Fortrat. F. Croze examining 
spectrum! 
of hydrogen, a systematic study of the Zeeman effect has 
enabled the lines belonging to bands to be separated from thos? 
