» found in Siberia, r 5 
which, on cooling, funk down. The mixture. of fulphur 
found.in yarious mafles, agrees. alfo exceedingly well with ~ 
the phenomena of fire-balls, and efpecially with the great 
inflammability of fulphur in yery thin impure air; for it is 
well known that fulphur in an air-pump will take fire in air 
in which few other bodies could do the fame. In regard to 
thofe maffes in which no fulphur was found, this may have 
arifen from the fulphur efcaping in vapour, fince fome time 
after the appearance of fire-balls a {trong fmell of fulphur 
has been perceived. The brittlenefs of the Siberian iron, 
mafs when heated, may arife from fome fmall remains of 
fulphur, which may perhaps be the caufe of the facility with 
which fragments of this mafs, as well as that found at Aix- 
la-Chapelle, could be roafted. 
2..The whole texture of the mafies betray ed evident figns 
of fufion. This, however, cannot have been ccunicea by 
any common. natural or artificial fire; and_particularly for 
this reafon, becaufe iron fo malleable is not fufible in fuch 
fire, and, when it is fufed with the addition of inflammable 
matters, lofes its malleability, and becomes like common - 
raw iron. . The vitrified fubftance in the Siberian mafs is 
equally incapable of being fufed in a common fire. The 
fire then muft have been much ftronger than, that produced 
by the common natural and artificial means, or the fufion 
muft have been effected by the force of' exceedingly ftrong 
electricity, or perhaps both cayfes may have been com- - 
bined together. | 
3. Befides the fimilarity of the above-mentioned maffes, 
the circumftances refpeéting their falling are fo like, that 
they cannot be confidered as merely accidental, and_there- 
fore give more credibility to the accounts. . This being pre- 
mifed, the principal queftion then is, whether the pheno- 
mena of this kind obferved were the effects of thunder, or 
arofe from detached fragments of fire-balls?. Several cir+ 
cumftances quoted by Dr. Chladni feem to oppofe the idea 
af their arifing from thunder; but agree fo perfectly. with 
B3 every 
