30 
STONES FALLING FROM THE AIR. 
Retrospect. 
lias to counterbalance this constant evaporation, and to puriff 
the atmosphere which contains all these volatilised matters. J( 
it probable that nature ctriploys other methods to purify the air j 
and it is most likely, that organized bodies are the most power- 
ful agents employed in this work. Plants especially seem to be 
charged with this office; they even appear to absorb mucilagi- 
nous matter, which has been proved by MM. Duputryen, 
Thenard, and Mocate to exist in the* air in a considerably large 
quantity. Vegetables are nourished by it; and this cause, 
together with several others, makes it possible to conceive how 
that plants set in matter which is incapable of supplying them 
with any alimentary moisture, should nevertheless vegetate and 
grow with strength. 
Such are the principal proofs, or rather the most decisive 
f lets, which give probability to the hypothesis, which considers 
aerolites as formed in our atmosphere. We can even assert, 
that these proofs are sufficiently strong to render this opinion 
deserving of more attentive examination ; and we are far from 
thinking with M. Bigot de Morogues, that this supposition 
itself is in any respect hasty or rash. With equal frankness it 
must be allowed, that the hypothesis of which we have been 
giving an account, is subject to a number of objections* ; but 
can it be proved as has been advanced, in my opinion, rather 
gratuitously by M. Bigot de Morogues, that aerolites have been 
♦ One of tlie strongest objections again.^t the hypothesis, which 
admits the formation of aerolites in the midst of terrestrial reijioiis, is 
the total absence of oxygen in the stone which fell at Li.^sa, and was 
analysed by KIat>roth. It is in fact siueular, that the particles of iron 
and martial pyiites should have been able to resist even a short inflamma- 
tion without heginiiiijg to be oxided. Butin the aerolites such as that 
whieli fell at Alais, the charcoal which I’.icy contained contiuned to 
bnin, and the silex which w'as separated from it, was not in the state of 
jelly as in the other metcorolites, which indicates that they had not 
experienced a great degree of heat. Tbi.s last fact is nnfaVourahle to 
the opinion, which considers aerolites as stones .slmt fmm the volcannca 
of the moon. See the analysis of a stone that fell at Alais the i.Mh of 
March, ItJOti, by M. Thenard ; Amiaies de CLiiuie. Auu 6 e, i uoti. p. 103. 
small 
