82 CONDITION OF THE SUN'S SURFACE. [MEMOIR IV. 



were an oxidation of a portion of the translated matter 

 when the spark is taken in air. The order of evolution 

 of rays in this instance happens to be the same as in the 

 second illustration of Professor Dove, that is, from the 

 violet to the red. There are certain facts connected 

 with these appearances of color which are not generally 

 known, and deserve to be pointed out. 



(I then give an abstract of the preceding memoir, and, 

 after speaking of the production of dark lines in the cy- 

 anogen flame, continue as follows :) 



In other cases dark lines are replaced by bright ones, 

 as in the well-known instance of the electric spark be- 

 tween metallic surfaces. The occurrence of lines, whether 

 bright or dark, is hence connected with the chemical nature 

 of the substance producing the flame. For this reason 

 these lines merit a much more critical examination than 

 has yet been given to them, for by their aid we may be 

 able-to ascertain points of great interest in other depart- 

 ments of science. Thus if we are ever able to acquire 

 certain knowledge respecting the physical state of the 

 sun and other stars, it will be by an examination of the 

 light they emit. Even at present, by the aid of the few 

 facts before us, we can see our way pretty clearly to cer- 

 tain conclusions respecting the sun. For since substances 

 which are incandescent, or in an ignited state, through 

 the accumulation of heat in them, show no fixed lines, 

 their prismatic spectrum being uninterrupted from end 

 to end, it would appear to follow that the luminous con- 

 dition of our sun, whose light contains fixed lines, cannot 

 be referred to such incandescence or ignition. At vari- 

 ous times those who have studied this subject have of- 

 fered different hypotheses: one regarding the sun as a 

 solid or perhaps liquid mass in a condition of ignition ; 

 another considering the light to be electrical; a third 

 supposing him to be the seat of a fierce combustion. 



