294 R. Meldoia—Bright Lines in the Solar Spectrum. 
into the en, gases compose m c 
paratively pnsil mass, such as those of oxygen and nitrogen, 
chromosphere, an — are thankies at a much lower tem- 
perature than that zo 
The elements hivtly concerned in producing selective ab- 
sorption in sun spots, as shown by the local thickening of their 
spectral lines, are all elements of high vapor density compared 
with oxygen—viz: Na, a, Ba, Fe, Ni, rom 
this it appears that the disturbances producing these phenomena 
must extend low down in the oe e band spec- 
enough to allow of the formation of compounds. 
7. It will help to give greater precision to the hypothesis of 
a zone of combustion, if we follow the course of a ray of light 
supposed to be euiitied by the photosphere and received in the 
spectroscope of a terrestrial observer. Passing through the re- 
versing layer, the ray undergoes that — absorption which 
om rise to oe Fraunhofer lines; and if its TL could be 
Lockyer, P: y. Soc., xviii; Young, Journ, Frank. si Sept., 1869 and 
tie. 1870; an a fo age Eni iii, p. 111, and vol. vii, p. 1 ; Respighi, Atti d. 
Real. Accad. d. oa 1872; Tacchini, Co omptes Ban os us, xxi, : ’ g29; H. C. Vogel, 
tungen, 1 - and numerous other 
Pb iapeesae! Young’ states (Nature, vii, p. ey that in wat he gente a sun- 
e observed “between C and D some very peculiar shadings. ath inated 
Roy. Astr. Soc., Nov. 9, 1877), a dark shaded band was seen at about wave-length 
6380, aahae toward the b Se shaded off toward the red. Nothing seen on 
aff 
really equivalent to aes molecules Pr compo 
