IV.] THE CHEMISTRY OF THE PKIMEVAL EARTH. 37 



by Mr. Grove with regard to water, whose elements, oxygen 

 and hydrogen, when mingled and kindled by flame, or by 

 the electric spark, unite to form water, which, however, at a 

 much higher temperature, is again resolved into its component 

 gases. Hence, if we had these two gases existing in admixture 

 at a very high temperature, cold would actually effect their 

 combination precisely as heat would do if the mixed gases were 

 at the ordinary temperature, and literally it would be found 

 that " frost performs the effect of fire." The recent researches 

 of Henry Ste.-Claire Deville and others go far to show that this 

 breaking up of compounds, or dissociation of elements by in- 

 tense heat, is a principle of universal application ; so that we 

 may suppose that all the elements which make up the sun or 

 our planet would, when so intensely heated as to be in that 

 gaseous condition which all matter is capable of assuming, re- 

 main uncombined, that is to say, would exist together in the 

 condition of what we call chemical elements, whose further dis- 

 sociation in stellar or nebulous masses may even give us evidence 

 of matter still more elemental than that revealed by the experi- 

 ments of the laboratory, where we can only conjecture the com- 

 pound nature of many of the so-called elementary substances. 



The sun, then, is to be conceived as an immense mass of 

 intensely heated gaseous and dissociated matter, so condensed, 

 however, that, notwithstanding its excessive temperature, it has 

 a specific gravity not much below that of water ; probably 

 offering a condition analogous to that which Cagniard de la 

 Tour observed for volatile bodies when submitted to great press- 

 ure at temperatures much above their boiling point. The radi- 

 ation of heat going on from the surface of such an intensely 

 heated mass of uncombined gases will produce a superficial 

 cooling, permitting the combination of certain elements and 

 the production of solid or liquid particles, which, suspended 

 in the still dissociated vapors, become intensely luminous and 

 form the solar photosphere. The condensed particles, carried 

 down into the intensely heated mass, again meet with a heat 

 of dissociation ; so that the process of combination at the sur- 

 face is incessantly renewed, while the heat of the sun may be 



