694 THE POPULAR SCIENCE MONTHLY. 



sion of the evidence already collected, or even a bare outline of it, 

 would lead us far beyond the limits of this article, which is simply 

 designed to show how much food for study even a feather will supply, 

 and what broad questions it will lead us into. 



WHAT THE CHEMISTRY OF THE ROCKS TEACHES. 



By C. C. MEREIMAN. 



IT is a general rule that substances can crystallize only while solidi- 

 fying from the liquid state of either fusion or solution. The only 

 exceptions are, that some few substances crystallize directly from their 

 vapors without passing through the intermediate liquid form. Now, the 

 older unstratified rocks of the geological formations, as the granites, 

 are unquestionably fusible, are crystalline in their structure, and are 

 practically insoluble. Therefore the evidence is conclusive that they 

 were all at one time in a molten, fluid state. 



Thus far, it would appear, geologists are agreed, since they have 

 named these formations the igneous rocks. But, whether the melted 

 minerals were ever heated to a higher degree than fusion — that is, to 

 the condition of vaporized elements — is an inquiry either carefully 

 avoided by the authorities in geology, or merely mentioned as pertain- 

 ing to an ingenious hypothesis which, it is claimed, is unsustained by 

 any sufficient proof. It remains to be seen, however, if this theory of 

 the original gaseous form of the material elements does not follow as 

 a necessary consequence from the chemical constitution of the rocks 

 themselves ; and if it does not explain and bear testimony in geologi- 

 cal and cosmical sciences to such an extent as to make it absolutely 

 essential to them. 



The question here presented resolves itself into two alternatives : 

 Either the materials of the earth's crust were formed, according to 

 chemical laws, out of the simple elements preexisting in liquid or gas- 

 eous form, or they were created in the condition of melted and oxi- 

 dized masses ready to cool into granite and limestone. The latter 

 supposition will hardly be seriously entertained in these days of free 

 inquiry into the natural causes of things. It is now not only conceded, 

 but expected, that science shall have sole jurisdiction in every case 

 where compound bodies are the subject of investigation. To follow 

 them back to the primal laws and elements of their being — to reveal 

 the cause and manner of their birth among the atoms — is now the 

 highest aim of inductive research. On this border-line of inquiry, 

 where the known shades off into the unknown, and the finite into the 

 infinite, science has of late gained its most signal triumphs. And it 

 scarcely requires a prophetic sense to discern that the groundwork of 



