55^ ConjeQures on the Stones which 



magnefia. But nothing is more rare in the volcanic pro- 

 ductions, with which we are acquainted, than magnefia, if we 

 except iron allayed with the nickel in the native" (late. Be- 

 fidds thefe ftones have been coliefled at fuch a dlllance from 

 all volcanoes, that the power which could fo long fupport 

 and convey through the air fuch enormous maflcs, would 

 be flill more inexplicable than their fpontaneous produc- 

 tion. 



Chemifts have proved, ift, That thefc ftone<, colledled in 

 places and at times difiant from each other, have a refem- 

 blance in regard to the fubllancts of which they are com- 

 pofed, and difier only bv the proportions of their elements r 

 ad, That they difier from all tlie other mineralogical com- 

 pounds found at the furface of the globe. It is natural, 

 therefore, to afifign to them all an origin of the fame kind, 

 and very different from that by which ihe minerals hitherto 

 obferved have been produced. 



Struck with thefe fingular charafters, C. Delaplace and 

 Biot mentioned, during the difcuflion which took place in 

 the National Inftitute in confenuence of Vauquelin's analy- 

 lis, a very bold opinion, but which is rendered probable by 

 the celebrity and charafter of its authors. According to 

 them, thefe ftones may be the produft of a volcanic eruption 

 in the moon. Comparing the mafs and denfity of the moon 

 with that of the earth, and calculating the didance between 

 our planet and its fatellite, they have eftabliflied that a vol- 

 canic eruption might projeft a body to fuch a difiance from 

 the moon as to be within the fpliere of the earth's attraction. 

 It is befides proved, by altronomical obfervation, that the at- 

 mofphere of the moon is exceedingly rare, and confequently 

 could oppofe very little refinance to the elevation of Ifones 

 projected from the moon. To this may be added, that as 

 the moon has Icarcely any atniofphere, this ci'cumftance 

 may ferve to explain why the metals contained in thefe 

 flones are not in the (late of oxide. 



But the fame obfervation which has difcovered volcanoes 

 in the moon, lliews tlieni in a ftate of luminous ignition, and 

 hitherto luminous ignition has never been known to take 

 place without oxygen. All the gafcs abforb caloric, and 

 on becoming concreie, fufter it to cfcape. Oxygen alone 

 poifcfres the property of abforbing light, and of emitting it 

 when it combines with bodies during combufiion. It thence 

 follows, I ft, That nietaljic fubflances projeCt'.d from the 

 moon ought to be oxidated, ai leaft in great part : .ad, That 

 the obfervations which prove the great tenuity or little ex- 

 tent of the atmofphere of the moon, ought. to jiiduce us.to 



. believe 



