H. HENSOLDT ON FLUID CAVITIES IN METEORITES. » 



Carbonic acid is a gas which can become reduced to the con- 

 dition of a liquid only under extreme pressure. Wherever we find 

 enclosures of liquefied carbonic acid in terrestrial rocks, (and we find 

 them frequently), we may take it for granted that the formation of 

 those rocks has taken place deep in the earth's crust, under the 

 gigantic weight of superincumbent masses. It has been found that 

 cavities containing liquefied carbonic acid often occur in Basalts and 

 other so-called basic lavas, which are known to be derived from deep- 

 seated reservoirs beneath volcanoes, where, besides the weight of 

 tremendous rock-masses above, we have the compressing force of 

 great quantities of elastic vapour held in confinement ; while in the 

 so-called acid lavas, of which we possess very conclusive evidence 

 that they are formed at no such very great depths, the presence of 

 liquefied carbonic acid is extremely rare and exceptional. The 

 fact that these liquid cavities are often contained in the crystals of 

 granitic rocks is regarded by geologists as a most important evi- 

 dence that the granites have been formed deep in the earth's crust, 

 under conditions of enormous pressure ; and we never find this 

 liquid in sedimentary strata, or any other materials which are un- 

 likely to have been exposed to extreme pressure during their 

 formation. 



It has been attempted to explain the presence of liquefied carbonic 

 acid in the cavities of crystals, by the assumption of its origination 

 through chemical processes, through changes which might have 

 taken place in certain portions of the crystals, leading to the 

 freeing and subsequent compression of the gas ; but even the most 

 ingenious argument which has been advanced, or could be advanced, 

 to support such a theory, on closer examination hopelessly falls to 

 the ground, leaving not the smallest room for doubt that all 

 crystals occurring in terrestrial rock-masses, whicli contain 

 enclosures of liquefied carbonic acid, must have been formed under 

 conditions of enormous pressure, which we can only conceive to 

 have taken place deep under the surface of our planet. 



But how about extra-terrestrial rock-masses? How about 

 meteorites in which we find liquefied carbonic acid in millions of 

 minute cavities? Could they have been originated under circum- 

 stances totally different from those which prevail on this globe ? 

 Could the carbonic acid in them have been condensed to a liquid 

 without extreme pressure ? Certainly not ; this would be little 

 short of a miracle, and as we cannot conceive the possibility of 



