160 INORGANIC EVOLUTION. [CHAP, 



nitrogen, oxygen, and carbon, and to a certain less extent they con- 

 tain proto-magnesium, proto-calcium, silicium, and sodium,* and pos- 

 sibly chlorine and lithium ; so that at last, by means of this recent 

 development of spectrum analysis, we have been able really to do for 

 the various stars what the biologist, a good many years ago, did for 

 the geological strata. 



It will be seen, then, that the answer to the question : " Do the 

 stars show a progression of chemical forms as the geological beds show 

 a progression of organic forms ? " is clear and precise. There is a. 

 progression. 



We are justified, therefore, in considering the matter further from 

 the evolution point of view. There are several points which merit 

 detailed consideration. 



Obviously we cannot expect to get much help by thinking along 

 several obvious lines, for the reason that in the stars we are dealing 

 with transcendental temperatures. For instance, we must not make 

 too much of the difference between gases and solids, because at high 

 temperatures all the chemical elements known to us as solids are just 

 as gaseous as the gases themselves ; that is to say, they exist as gases ; 

 at a high temperature, everything, of course, will put on the nature 

 of gas. Those substances with the lowest melting points, such as- 

 lithium and sodium, will, of course, under our present conditions put 

 on the gaseous condition very much more readily than other substances 

 like iron and platinum, but those are considerations which need not be 

 taken into account in relation to very high stellar temperatures ; of 

 course, there would be no solids at a temperature of 10,000 C., and 

 there will be no gases in space away from the stars if the temperature 

 of space be taken at absolute zero. 



Then with regard to metals and non-metals. Here again we really 

 are not greatly helped by this distinction. The general conception of 

 a metal is that it is a solid, and that, therefore, a thing that is not a 

 solid is not a metal : but the chemical evidence for the metallic nature 

 of hydrogen has been enlarged upon by several very distinguished 

 chemists, and mercury is generally known as a liquid. With regard to- 

 non-metals, there are certainly very many. Carbon is supposed to be 

 a non-metal, and it is remarkable that, so far as the stellar evidence has 

 gone as yet carbon seems to be the only certain representative of that 

 group. 



I must point out specially that the table of the chemical defini- 

 tions of the various stellar genera (given on pp. 70 and 71), which 

 contains nothing but hard facts, is perhaps, like the geological record,, 



* Campbell, Astronomy and Astro-physics, 1894, Tol. xiii, p. 395. 



