. 
Obferviations on the Fog of 1783. 87 
ferclutions of the earth, over which they have an influence . 
dn their turn.. If we confider the different bodies or fub- 
ftances of which that part of the earth known to us is com- 
poled, we fhall fee that, notwithftariding their apparent reft; 
they all obey, as we may fay, an inteltinal motion; and 
that this motion gives continual rife to new ¢ompofitions 
and combinations, the connection of which efcapes us, but 
which neverthelefs exift. The remains of animals and ve- 
getables flill diftinguithable, and which occupy fo much 
room in our globe; the acids which attack them; the aén- 
form fluids difengaged from them; the metals and pyrites 
brought to perfection, or decompofed ; the fires feparated, or 
collected; the fermentations and efferyvefcences; in 2 word, 
the innumerable decompofitions and recompofitions of all 
the parts of the earth, furnifh abundance of fubtle matter, 
which, by its levity, difengages itfelf at the furface of the 
globe, cannot, in certain circumftances, refilt the gravity of 
the air, and rifes fometimes to the fummit of the atmofphere. 
On the other hand, the rains which fall, moift fogs, and fe- 
veral other caufes, make a part of the water, which des 
taches itielf from the airs to penetrate the earth, and to coms 
bine with the fubftance of thefe exhalations. It is afters 
wards, i part, attracted by the external heat, or repelled by 
the heat of the earth itfelf; but it never returns to the atmo+ 
{phere as pure as it was when it iffued from it. It carries 
with it a great part of that fubtle matter of which I have 
fpoken; and it is-this afterwards which produces thunder, 
and almoft all fiery meteors, There is then a continual 
communication from the earth to the atmofphere, and from, 
the atmofpbere to the earth. The greater part of thefe ex- 
hhalations, in general, is fpecifically heavier than the atmn~ 
fpheric air; and, if they are not impregnated with a certain 
quantity of water, they cannot quit the earth. They muft 
neceflarily be there collected, and accumulate to a greater or 
Jefs depth in the time of great droughts. 
Let us now confult our regifters, and thofe of different ob~ 
fervers, and we fhall fee that there had prevailed, at leaft tor 
mine years, an extreme drought, not only in Europe, but 
alo in Africa and America, This was announced year after 
year 
