98 On the Equivalent and Spectrum of Cesium. 
__ For the convenience of those who may use spectroscopes of 
the same construction as ours, we will mention the degrees on 
the scale of our instrument, which correspond to the cesium 
lines. In our observations we have brought the degree 100 (10 
on the scale) into the sodium line. Then the blue of strontium 
is at 156°, the violet of potassium 257°, the red of potassium at 
65-6° ; the red of lithium at 80-1°. With this adjustment the 
czesium lines are as follows, beginning with the red: : 
IT 80°, III 82-3°, IV 85°, V 87-8°, VI 91°, VII 97-8°, V 
101°, TX 106°, X 107-8°, XI 109°, XII 111°, XIII 112-13’, 
XIV 114-15°, XV 118°, XVI 121°, XVII 157-58°, XVI 
zt °o 
The position of the czesium lines on the scale figured = * 
ho 
~I 
kt en 
oo 
| 
at the top of the spectrum plate in Fresenius’ Zeitschrift, =— 
is approximatively given in the accompanying diagram, = _u 
by help of which our results may be directly compared = ~ 
with those of Kirchhoff and Bunsen. ae 
The order of brilliancy in the lines of what we sup- =—¥ 
ose to be the spectrum of pure cxsium, with but the = 
minutest trace of sodium, is for the red lines as follows: =~ 
; e line IV is only made =—® 
out under the most favorable conditions. II, nearly {=_ 
coincident with « lithium of Kirchhoff and Bunsen, and & 
not figured by them, is as bright as their y cesium, our &=—5 
VI(?). Among the yellow and green lines to the right =— — 
of the sodium line, the order of brilliancy is the follow- @_ 2 
ing: VIII, IX, XI, XU, XIV, XIII, XV, X. The = 
yellow line VIII, is hardly less characteristic of the =— 
spectrum of pure cesium than the two blue lines. It ==—g 
also is nearly as distinct as any of the green lines when &_ 
sodium is not present in too large quantity, and is much <& 
more readily made out than the extreme red line d of =~ 
rubidium. = 
To sum up, we find 4 red lines to the left of those = 
given by Kirchhoff and Bunsen, one of which is as bright =~ 8 
as any of the red lines in the cesium spectrum. Fur- =— 
ther, the red lines of K. & B. are not figured in their =_g¢g 
true positions, being too near each other and too far to 
the right. Finally, we observe a fine yellow line and 4 
i 3 
two unimportant green lines not ane a by K. & B. 
The lines which we have supplemented to those of K. 
& B. are not characteristic except in the absence of for- 
eign matters. For this very reason however they 
come important to those who are engaged in the study 
of the new elements. 
New Haven, Conn., Dec. 24th, 1862. 
OL 
MA Ty 
