130 ANNUAL OF SCIENTIFIC DISCOVERY. 



as is proved by prismatic examination, when all the colors are perceptible. 

 And the reason of this is, that at the high temperature to which the sulphur 

 is exposed, it volatilizes faster than the nitrate of potash and air together can 

 oxidize it, and offers every intermediate rate of combustion, and emits rays 

 of every refrangibility. 



In like manner it may be shown that carbonic oxide must burn with a blue 

 flame, and cyanogen with a red. "We can also foresee what must be the 

 optical result of resorting to unusual methods of combustion, as when we 

 throw into the interior of a flame a jet of air from a blowpipe. In this case 

 we destroy the red and orange strata, replacing them by bluer colors. Ex- 

 amining such a blowpipe cone by the prism, we have a beautiful demonstra- 

 tion that such has actually taken place. 



There is one of these special cases which deserves attentive consideration 

 in connection with the appearance of the electric light ; it is the production 

 of Fraunhoferian lines, when things have been arranged in such a way that 

 an incombustible material is present in the substance to be burnt. This 

 state is perfectly represented in the case of cyanogen, which contains more 

 than half its weight of incombustible nitrogen. When the peach-colored 

 nucleus of the cyanogen flame is properly examined, it yields a series of 

 dark lines and spaces exceeding in number and strength those of the sun- 

 light itself. These fixed lines are the representatives of dark shells, super- 

 posed among the shining ones with definite periodicity. In such a cyanogen 

 flame they bear no relation to the burning of the carbon, but must be attrib- 

 uted to the disengagement of the nitrogen. 



In other cases dark lines are replaced by bright ones, as in the well-known 

 instance of the electric spark between 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 they merit a much 

 more critical examination than has yet been given them; for by their aid we 

 may be able to ascertain points of great interest in other departments 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 certain conclusions respecting the 

 sun. For, since substances which are incandescent, or in the ignited state 

 through the accumulation of heat in them, show no fixed lines, their pris- 

 matic spectrum being uninterrupted from end to end, it would appear to 

 follow that the luminous condition of our sun, whose light contains fixed 

 lines, cannot be referred to such incandescence or ignition. At various times 

 those who have studied this subject have offered different hypotheses; one 

 regarding the sun as a solid or perhaps liquid mass in a condition of igni- 

 tion; another considering the light to be electrical; a third supposing it to be 

 the seat of a fierce combustion. Of such hypotheses we have given reason 

 for declining the first. Prismatic analysis, which demonstrates no resem- 

 blance between the light of the sun and that of any form of electric dis- 

 charges with which we are familiar, enables us in like manner to reject the 

 second ; and upon the whole, facts seem most strongly to prepossess us in 

 favor of the third, in artificial combustions similar fixed lines being observed. 

 If such is to be regarded as the physical condition of the sun, we can no 

 longer contemplate it as an immense mass, slowly and tranquilly cooling in 

 the lapse of countless centuries by radiation into space, as so many consider- 

 ations drawn from other branches of science have hitherto led us to suppose; 



