424 ' Scientific Intelligence. . 
salted aleohol flame placed between the lime cylinder and the slit, pro» 
duces two dark lines of extraordinary sharpness and fineness, which ex- 
actly correspond to the lines D of the solar spectrum. In this manner 
these lines are artificially produced in a spectrum in which they do not 
actually occur, re 
If we introduce chlorid of lithium into the flame of Bunsen’s gas lamp, — 
the spectrum exhibits a very bright, sharply defined line, which lies in 
the middle between Fraunhofer’s lines B and C. If we allow solar rays of ; 
moderate intensity to pass through the flame to the slit, we see the line 
bright upon a dark ground; but with a greater intensity of the sunlight — 
a dark line occupies its place, which has precisely the character of Fraun- 
hofer’s lines. When the flame is removed, the line vanishes completely, 
The author concludes from these observations that colored flames in 
whose spectra bright sharp lines occur; diminish the intensity of rays of 
spectrum of a flame always arise from the presence of sodium ; the das — 
< r e that sodium 
their blowpipe flames. In pursuing together the investigation 
hoff’s discovery of the influence of flames upon rays © li 
m 
mond’s light requires a salt-flame of low temperature in or 
D may appear dark. The flame of alcohol and water 1s 4 if 
purpose, but the flame of Bunsen’s gas lamp is not. In this last ca86 © 
smallest perceptible quantity of salt causes the bright lines get 4. 
The authors reserve the developement of the consequences OFM 
able fact—Pogg. Ann., cix, p. 148, January, 1860. ‘iad 
Note—Professor Stokes, in a letter to the editors of the L. : 
Mag. directs attention to the fact that Foucault, in 1849, publ 
od in l'Institut containing observations exactly analogous 
‘irehhoff. Foucault’s experiments were made by t 
through the galvanic arc, and appear to have escaped atte 
their second and independent discovery by Kirchhoff. 
to 
