CHEMISTRY OF THE ROCKS. 65 



was originally combined only into carbonic acid gas ; that both 

 were brought to the surface of the earth in solution with rain- 

 water ; and that sulphur in this form united with the metals which 

 had failed to be oxidized upon their condensation in the air, and 

 also sulphated the quick-lime in the earth which had not been 

 carbonated by the carbonic solution. Then there is the exceptional 

 production in nature of the chloride of sodium common salt. 

 Apparently in this one instance the oxide is the less stable com- 

 pound. 



But if, as we have endeavored to prove, there is a necessity of 

 accounting in accordance with this theory for the various com- 

 pounds and phenomena with w r hich geology makes us familiar, 

 then it is in the highest degree essential that experiment and re- 

 search be prosecuted in this new field. And there must be no 

 hesitation in accepting the conclusions to which they lead. 

 Should the nebulous origin of one planet be thus established 

 by internal and inductive evidence, then the nebular theory of 

 the formation of worlds, which has heretofore been received as 

 only a provisional hypothesis, must be accepted as having a scien- 

 tific basis. If the earth has once been a self-luminous body, in 

 all respects excepting size like the sun of to-day, it follows from 

 anology that the other planets have likewise been minor suns 

 which have become extinguished by the burning out of their mate- 

 rials. To an observer on any unseen world among the stars, our 

 sun should have appeared in those times as a brilliant double or 

 multiple star, around which nine lesser companions have shone 

 out for a season, and then one after the other folded themselves 

 up in darkness. 



Furthermore the study of this subject may throw light on 

 many cosmical problems may tell us in earth- periods if not in 

 years, how old the sun is when his glowing vapors begin to con- 

 dense into dark clouds, and perhaps too something of his future 

 prospects as a luminary. It is remarkable that the spectrum has 

 never shown any indications of free oxygen in the atmosphere 

 of the sun. Is not the absence of this element further corrobo- 

 rated by the fact that the solar spots which, there is evidence to 

 believe, are condensing clouds of iron and calcium, do not glow 



