WHAT IS THE SUN MADE OF ? 459 



Repeating the experiment with other metals, we produce 

 other black bands 011 our artificial spectrum, conformable in 

 every respect to other Frauenhofer bands. And thus, by fol- 

 lowing out this beautiful train of reasoning, philosophers have 

 arrived at two conclusions : First, that the sun, as was an- 

 ciently supposed, is a mass of molten fire ; second, that he 

 is surrounded with a blazing atmosphere, in which at least 

 exist the metals iron, magnesium, sodium, chromium, and 

 nickel. 



Nor have the experiments of Professors Bunsen and Kir- 

 schoff, of Heidelberg (to whom these discoveries are due), only 

 revealed a new mode of analysis for substances already known, 

 but they have actually succeeded in discovering two new al- 

 kaline metals, to which the names ccesium and rubidium have 

 been given. Subsequently our own countryman Mr. Crookes, 

 using spectrum analysis, discovered the new metal thallium. 

 Indications of both these metals having been recognised in 

 the waters of Baden and Durckheim, the professors, after a 

 tedious course of manipulation, succeeded in obtaining them. 

 It now remains to be seen whether this beautiful spectral 

 analysis may not be hereafter applied to the discovery of 

 mineral poisons. 



