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Water petrified, as they are found commonly near 
Falls of Water which is impregnated with the like 
flony Matter : And as the fmallcft fcattered Drops of 
Water fly farthcfl from the Centre, they fo account 
for the gradual Diminution in Magnitude of the 
‘ Pifolilhi . Others affirm they grow from the Vapour 
of this petrific Water, though they cannot tell how. 
Amidft this Uncertainty, I derermined, whilft I 
was on the Spot, to fpare no Pains to icarch after 
(and difeover, if poflible) the manner how thefe re- 
gular globous Bodies are produced. I have already 
told you, that the Waters of thefe hot Springs at 
Carlsbad are fo replete with tophaceous Matter, that 
where- ever they run, Mafles of 'Tophus are formed j 
aud when thefe Waters are cold, a Scum (like the 
little Scales of the fame Matter) rifes on the Top, 
fomc of which I fend you, and I believe you will 
think it, on Examination, littie or nothing different 
from the Subfiance of the component Matter of the 
Pifolithi, or from that which forms the common 
Tophus, which 1 fuppofe to differ from the Tijohthi 
only in Appearance. 
Firft of all, I obferved in the Chinks and Hollows 
of the ordinary Rock-ftone very fmall Molecule 
loofely adhering; 1 found alfo Clufters of Tijolithi 
in the like Places, and cn breaking up a Piece of the 
Rock by the Side of the River, where it had been 
burft by the Water, I difeovered Mafles of Tifolithi 
lying in the Chinks, and many loofe ones twirling 
round and played about in the bubbling Water. 
My Suppofition therefore is, that the Stream de- 
scending from the Body of the eppofire Mountain, 
pafling beneath the River, and afterwards burfting 
out 
