ae 
co 
pa 
Gr 
j I Z 
j ZIE hm Dbl sle| a | a ae 
5115.55 «6 680 | | 
5265.89 1 
5268.59 2 
5371.64; 4 | 
5592.44 4 | 
5615.00 3 | 1060 
5715.31 5 1160 
5761.10 3 | 990 
Mean: 678 | 16.4 | 9.7 | 11.6 | 9.5 46 38 | 43 | 43 
The ratios given in the last column are sufficiently indicated by 
the symbols at the head. 
From the observation-material given above it is evident that there 
are still many observations to be made before we shall be able to 
compare ZrrMar-effect and pressure-effect for each given spectrum- 
line. Most observations have been made for the groups I and II. 
For group Ill fewer. It is remarkable that just in this group nearly 
all determinations of a magnetic resolution are missing. Though 
also in the following groups some investigations of this effect are 
missing, this lack is so conspicuous in the third group that the few 
measurements eccurring in column Z more resemble exceptions. 
Already this phenomenon proves the suitableness of a division into 
definite gronps. Of the lines of this group we might then say the 
following: 
These lines taken together in one group because at an increase 
of pressure they remain bright and narrow, show also the same property 
to be of so small intensity at an investigation in a magnetic field, 
that they are not or hardly observable. So Miss GRAFTDIJK gives 
for the three lines of which still a 4. E. could be determined the 
intensities: 2, 2, 1, so that they belong to the weakest visible lines. 
Therefore the circumstances under which in Miss GRarrpisk’s 
experiments the spark-spectrum was excited (with an ordinary in- 
duetor) prove to bave been such, that the lines of group III together 
could not reach a sufficient or only an exceedingly small intensity. 
85 
Proceedings Royal Acad. Amsterdam. Vol. \VIII. 
