CHEMISTRY SINCE TIME OF DALTON 



chemists were amazed or delighted, according to their 

 various preconceptions, to witness the proof that many 

 familiar terrestrial elements are to be found in the ce- 

 lestial bodies. But what perhaps surprised them most 

 was to observe the enormous preponderance in the si- 

 dereal bodies of the element hydrogen. Not only are 

 there vast quantities of this element in the sun's atmos- 

 phere, but some other suns appeared to show hydrogen 

 lines almost exclusively in their spectra. Presently it 

 appeared that the stars of which this is true are those 

 white stars, such as Sirius, which had been conjectured 

 to be the hottest ; whereas stars that are only red-hot, 

 like our sun, show also the vapors of many other ele- 

 ments, including iron and other metals. 



In 1878 Professor J. Norman Lockyer, in a paper be- 

 fore the Royal Society, called attention to the possible 

 significance of this series of observations. He urged 

 that the fact of the sun showing fewer elements than are 

 observed here on the cool earth, while stars much hotter 

 than the sun show chiefly one element, and that one 

 hydrogen, the lightest of known elements, seemed to 

 give color to the possibility that our alleged elements 

 are really compounds, which at the temperature of the 

 hottest stars may be decomposed into hydrogen, the 

 latter "element" itself being also doubtless a com- 

 pound, which might be resolved under yet more try- 

 ing conditions. 



Here, then, was what might be termed direct experi- 

 mental evidence for the hypothesis of Prout. Unfortu- 

 nately, however, it is evidence of a kind which only a 

 few experts are competent to discuss so very delicate 

 a matter is the spectral analysis of the stars. What is 



VOL. IV. 6 1 



