on the spark spectra of titanium, chromium and manganese. 43 
These values are fairly comparable ; and the ratio of the con- 
stituents of the sextuplets appears to be 1:3: 4, whilst the 
values of the outside constituents of the triplets are comparable 
with the extreme constituents of the sextuplets. The numbers 
may be represented as simple multiples of 0'68, the index 
numbers being 1, 3 and 4. 
The values of the constituents of the Cd. lines seem to be 
a little higher than the corresponding ones of Zn. and Mg., but 
the differences are probably due to errors in the measurements, 
and particularly as the extreme constituents of the sextuplets 
impinged so closely upon their neighbours that it was difficult 
to strike their centres of gravity. 
The following notes describe the results of experiments with 
titanium, chromium and manganese. The same apparatus was 
used as in the experiments with the other metals. The strength 
of the field was 39,980 units, and only those lines were measured 
whose constituents left well marked images on the photographic 
plate during an exposure of 30 minutes. 
The column A gives the wave lengths of the lines ; the 
distances between the constituents of the divided lines are omitted, 
but the values of c?A/A 2 calculated from them are given, and a + 
sign means that the constituents are on the side of greater wave 
length and a — sign of shorter wave length. The letters s and p 
signify as before that the constituents vibrate so that their electric 
vectors are respectively perpendicular or parallel to the lines of 
force. The remark “the middle constituent removed by calcite” 
means that the constituents were so close, or intense or diffuse 
that they could only be seen separately by cutting out those 
parallel to the lines of force by introducing a calcite prism be- 
tween the source of light and the condensing lens. 
Titanium. 
The lines were identified by comparison with the measure- 
ments and descriptions of Exner and Haschek (Sitz. d. k. Akad. 
Wien, Vol. cvir. n^. Abth. p. 796) for wave lengths from 4747’83. 
The line 325203 was divided into six constituents, which 
appeared to be equally sharp and strong. The measurements 
were taken between corresponding constituents. The values of 
dA/A 2 are in the simple ratio of 1:3:6. 
\ 
(?X/\ 2 
325203 
+ 2-82 s 
+ 1-40 2 ? 
+ 0-47 2? 
0 
- 0-47 r 
- 1-40 j> 
- 2-82 a 
