340 EXPERIMENTS RELATIVE TO METEORITES. 



The most important difference consists in the fact that, in the meteorites, 

 nothing has been found which resembles the materials that constitute the strati- 

 fied formations — neither arenaceous rocks, nor fossiliferous rocks ; that is to say, 

 nothing which testifies to the action of an ocean on these bodies any more than 

 to the presence of life. 



A great difference is manifested, even when we compare the meteorites with the 

 terrestrial rocks not stratified. Never has there been met with in the meteorites 

 either granite, or gneiss, or any rocks of the same family which form, with these, 

 the general layer on which rest the stratified formations. We do not even 

 observe there any of the constituent minerals of granitic rocks — neither orthose, 

 nor mica, nor quartz — any more than tourmaline and other silicates which are 

 associates of those rocks. 



Thus, the silicated rocks which form the envelope of our globe are wholly 

 wanting among the meteorites. It is, as has been seen above, in the deeper 

 regions only that we must seek the analogues of these latter ; in those basic 

 silicated rocks which only reach us in consequence of eruptions by which they 

 have been expelled from their primitive repository. In every point of view, the 

 absence in meteorites of the whole series of rocks which constitute, to so great a 

 depth, the crust of the earth is a cu'cumstauce well calculated to arrest attention, 

 whatever may be the cause. 



This absence may be explained in different ways; whether it be that the 

 meteoric fragments which reach us do but proceed from the internal parts of 

 planetary bodies constituted like our globe ; or whether these planetary bodies 

 themselves are deficient in silicated quartziferous or acid rocks as well as in 

 stratified formations, In this latter case, which is the most probable, thej' must 

 have passed through evolutions less complete than the planet we inhabit ; and it 

 is to the co-operation of the ocean that the earth has owed, in its origin, its gran- 

 itic rocks, as it has owed to the ^ame agency, at a later period, its stratified 

 deposits. 



GENERAL OBSEEVATION. 



In fine, the privilege of uhiquity pertaining to peridot, as well in our deep 

 subjacent rocks as in the meteorites, is explained, as the preceding experiments 

 show, by the fact that it is in some sort the universal scoria. 



It may be concluded from what precedes that oxygen, so essential to organic 

 nature, must also have played an important part in the formation of the planetary 

 bodies. Let us add that without oxygen we can conceive of no ocean, nor of 

 any of those great functions, whether superficial or profound, of which water is 

 the cause. 



We thus touch on the foundations of the history of the globe, and draw closer 

 the bonds of relationship, already disclosed by the similarity of their composition, 

 between the parts of the universe whose nature it is given us to know. 



APPENDIX. 



DEVELOPMENT OF THE COLLECTION OF METEORITES OF THE MUSEUM. 



For the thorough study of meteorites it was indispensable to possess a collec- 

 tion in which the descents which have occurred in different countries should be 

 represented in as complete a manner as possible, and in which they might be 

 examined and compared with one another. For this reason it is proper to say a 

 few words on the development of the principal collection of France. 



