FOG. 
5d0 
decompofed, and the nafcent hydrogen fo readily blended 
with azof, as to prothice ammonia. 
The mod extraordinary fog, of which we have any ac. 
count in hidory, occurred in the month of June 1783. 
Of this the following datement is given by M. Toaldo, 
of Padua, in the Journal de Phyjique : “Two particular 
phenomena are to be noticed, as having accompanied 
this remarkable fog, viz. exceffive rain, and violent thun¬ 
der. On the morning of the iSth of June, after a dorm, 
which had been preceded by feveral others, the fun ap¬ 
peared extremely pale through the fog, which now filled 
the whole atmofphere. This fog became dill more con- 
denfed the following days ; and was not diffipated by the 
winds, nor even by the dorm of the 26th in the morning, 
accompanied by a great deal of thunder, which was heard 
all along the direction of the mountains from one fea to 
the other. This fog dill exided in the beginning of July, 
and feemed to become thicker, at lead at certain hours. 
It did not prevent the fun or dars of the fird magnitude 
from being feen, except in the lower part of the horizon. 
People could look at the fun without being incommoded, 
and without ufing coloured or fmoked glafs. It appeared 
of different colours, according to the kind of rays which 
the difference in the denfity of the fog fud'ered to pafs. 
As the yellow and red, being the dronged, were thofe 
which pierced it oftened, the fun appeared like a ball on 
fire, or of a blood colour ; which gave occafion to many 
fanciful people, whofe imaginations were heated, to think 
, they faw there, as in the clouds, the figures of men and 
animals. Very often the fun, in the higher part of the 
atmofphere, feemed pale and white by the abfence of fe¬ 
veral coloured rays ; and he appeared red when he was 
lower, becaufe his rays then palfed through a great por¬ 
tion of the atmofphere. The dars were often vifible at 
noon-day through the fog. 
“ That it may not be imagined that this phenomenon 
is new in the world, I diall give a (hort account of thofe 
obferved formerly, analogous to it. But it will fird be 
proper to fay a few words refpedting the caufe of this ex¬ 
traordinary fog, which I am inclined to think came from 
Sicily and Calabria, where there were violent earthquakes. 
We know, by the accounts given, that the heavens in 
thofe countries appeared cloudy after the great (hocks, 
which may be readily believed when we confider the im- 
menfe exhalations that mud have been difperfed through¬ 
out the atmofphere. In the month of June the fouth- 
ead winds prevailed throughput all our country. Thefe 
winds at Venice are called Foriani, becaufe they fird take 
place on this fide of the gulf.- It is very probable that 
thefe winds, truverfing that part of the atmofphere, may 
have carried with them a large mafs of exhalations, which, 
being dopped by the chain of the Alps, difperfed them- 
felves in Lombardy, and occupied even the Alps, which 
people, with adonifhment, beheld red, or of different co¬ 
lours, according to the polition of the fun and of theob- 
ierver. It does not appear that thefe exhalations arofe 
from our territory, which was not feen to fmoke, as is ge¬ 
nerally the cafe in the time of a fog; but it proceeded 
downwards , as if it had fallen from the atmofphere. It 
was not feen to touch the earth, except when, by an op¬ 
tical illufion, the nebulous dratum, by being lengthened, 
appeared united with the fenfible horizon. It occafioned 
no hurt, therefore, to the fruits of the earth ; it is faid 
only that it bladed the olives and vines a little on the 
elevated grounds. If any differed in the flat country, 
the caufe may be afcribed to the rains which took place 
at the time when they were in bloom. 
“ If this fog arofe, as I have faid, from exhalations dif- 
engaged at the time of earthquakes, it mud have been 
dry, and mud have contained abundance of earthy, fiery, 
mineral particles, with a great deal of inflammable air and 
electric fire. To thefe may be afcribed the frequent 
thunder which took place, efnecially towards the middle 
of the month. The thunder in general made dreadful 
ravage, burning houfes, and dedroying men and animals. 
Letters from Hungary date, that, after feveral dtocks of 
an earthquake, the city of Kremnitz was fet on fire by 
lightning. The fame fate was apprehended for Vicenza 
on the morning of the 26th, the repeated claps of thunder 
being fo viol* nt. Five or fix houfes were that day dtuck 
by the lightning, which occafioned confiderable damage. 
The lightning fell alfo in about a dozen different places 
in the neighbourhood, particularly in the mountains.” 
The fame fog is accurately defcribed by M. De Lama- 
non, of the National Inditute at Paris ; who differs in 
opinion from M. Toaldo, as to its caufe. His datement 
is as follows: “ When this fog, which may be called an 
eledtric fog, began to appear, I was at Sallon de Crau, in 
Provence. In order to free my neighbours from uneafi- 
nefs as much as podible, I wrote a letter to M. Artaud, 
editor of the Courier d’Avignon, in which, after fpeaking 
of the nature of the fog, I faid it would be dedroyed by 
the dorms that would enfue. The event fully judified 
the predidtion. Having learned from the public papers 
that this phenomenon was not local, but almod general 
throughout Europe, I made new obfervations, and tra- 
verfed the highed Alps of Provence, Dauphiny, and Pied¬ 
mont; and, during the courfe of my travels, collected in¬ 
formation refpedting the fog, and the effedfs of the thun¬ 
der. But before I offer that explanation of the pheno¬ 
menon, which appears to me mod probable, let me en¬ 
deavour to give an accurate defcription of it. 
“ In almod all countries the fog was preceded by a 
dorm. It began the fame day at places very remote from 
each other; as Paris, Sallon, Turin, Padua, &c. where 
it appeared, for the fird time, on the 18th of June. M. 
Senebier wrote to the count de Saluces, prefident of the 
Academy of Turin, that the fog was obferved at Geneva 
on the 17th ; and it began at Grenoble on the 21 d. A 
north wind prevailed in feveral places when the fog began ; 
and in other places, where it began the fame day, a fouth 
wind prevailed. The fog, after having ceafed, re-ap¬ 
peared in fome places by the north wind ; in others, by 
an ead, wed, or fouth, wind. The atmofphere was not 
every where equally dry. At Sallon I obferved that it 
did not make La!ts enter into deliquefcence ; did not raife 
the hygrometer; did not prevent evaporation from being 
abundant; and did not even tarnifh glafs which I expofed 
to it. The fait-pits at Hyeres, in Provence, crydallifed 
a fortnight fooner than ufual by the eft'efil of the fog. 
Mefl'rs. Toaldo and Senebier obferved, the one at Padua 
and the other at Geneva, that the hygrometer did not 
reach the point which denotes humidity. In the Champ>- 
faur of Dauphiny, and at Turin, the fog was fometimes 
h u mid. 
“ The fun, which was never feen but through the fog,, 
appeared very pale in the day-time ; of a blood-red co¬ 
lour at riling, and dill more (o at fetting. At Sallon the 
fog .fometimes diffufed a very difagreeable fmell, difficult 
to be determined, and which fome believed to be fulphu- 
reous. This bad fmell was perceived in other places. 
It was hurtful to the eyes. At Sallon, perfons whofe 
lungs were weak, found difagreeable effedds from it. The 
inhabitants of the Champfaur informed me that feveral 
people in that neighbourhood had violent pains in the 
head ; and that, in general, they lod their appetite. In 
Lower Provence, Languedoc, and other places, the fog 
ripened the corn, and was favourable to the harved. The 
peafants beheld, with the greated fatisfaftion, the effedt 
of the fog on their crops ; and yet were afraid of it. In 
Upper Dauphiny, and at Turin, it blighted feveral fields 
of wheat, and rendered copper buttons green. In other 
places it dried the plants. At Padua, Turin, Paris, Sal¬ 
lon, Grenoble, the barometer remained almod always da- 
tionary at the point which denotes its mean date. 
“ There were fome days remarkably warm ; bur, in ge¬ 
neral, the months of June and July were almod every 
where lefs warm than ufual. That year there was no 
fummeron the high mountains of Provenceand Dauphiny, 
where the fltepherds of the plains of Crau and Camargue 
tend 
