Fae 3h bat 
Sr AAG 
e , 0 
‘one 
tp ae 
te 
e. Objervations on @ Mafs of Iron " 
paflage through the high regions of the atmofphere, ocea-" 
fion only a tranfient electric flath, or actually take fire for a 
moment, and are again fpeedily extinguifhed, when they. 
get to fuch a diftance from the earth that the air becomes 
too much rarefied for the exiftence of fire. 
~ The grounds on which ‘Dr. Chladni founds the above the- 
ory, refpeéting the origin of the before-mentioned mafs of 
ifon, and its fimilarity to the productions of fire-balls, are 
farther explained by the author in the following manner =” 
1. As fire-balls confift of denfe and heavy fubftances, which 
by their exceedingly quick movement, and the friétion thence 
excited by the atmofphere, become eleétric, are reduced to 
a ftate of ignition,»and melted by the heat, fo that they 
extend to a great.fize, and burft; it thence follows, that in 
places where fragments, produced by the burfting of a fire- 
ball, have been found, fubftances endowed with all thefe pro- 
perties muft alfo have been found. Tron, however, the prin- - 
cipal component part of all the maffes hitherto found; pof- 
feffes all thefe properties ina very eminent degree. The 
weight and toughnefs of the principal component parts of 
fire-balls, which muft be very confiderable, fince, with the 
greateft poflible diftenfion, they retain confiftenee: enough to 
proceed with the utmoft velocity through fuch an immenfe 
{pace without decompofition of their miafs, and‘ without 
their progrefs being obftructed by the refiftance of the air, 
agree perfectly well with melted iron; their dazzling white 
light has by many obfervers been compared to that of melted 
iron; iron alfo exhibits the fame appearances of flaming, 
fmoking, and throwing out fparks, and all 'thefe pkegne 
mena are moft beautiful when they take place in vital air. 
Of the extenfion by elaftic fluids expanded by the heat, and 
of the contraction which follows from cold, traces may be 
difcovered in the internal fpongy nature of the iron maffes | 
which have been found, ‘and in the globular deprefiions of . 
‘the exterior hard cruft, the latter of which gives ws reafon to 
i i ‘that-in ‘thefe ee there: have been air-bubbles, 
which, 
