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cloſed by a Cruſt formed of the Matter within; and ſo well ſtopped, that no Vapour eſcaped.
After this the Retort became corroded in a great many Places: Fumes iſſued, at them all, for a little While; but they were afterwards ſtopped by Cruſts of the fame Kind as the former.
When the Operation was finiſhed, there were found in the upper Part of the Retort a Kind of Flowers, dry and powdery; and in the Neck a thick, ſlimy, moiſt Subſtance.
The Retort was corroded all round, juſt above the Top of the Reſiduum; and this corroded Part crumbled to Duſt between the Fingers; having loſt the Nature of Glaſs.
Here then is found a Foſſil capable of diſſolving Glaſs; a Power not known in any other Body:
Subliming an abſolute Stone during the Diſtillation; a Quality equally unknown in other Bodies:
And burning with a violet, ſcentleſs Flame: A Thing equally unknown; and the more ſtrange, as the Stone holds no Copper.
To ſhew the violet Flame, ſome of the Stone is to be broken ſmall with a Hammer; and ſprinkled on a red hot Heater, in the dark: The Flame riſes very freely, and continues ſome Time; and the Stone ſplits into thin irregular Flakes
The Uſes of the pure Acid may be infinite: And it is eaſy to ſee the Knowledge of this Subject will lead us to a thouſand unknown Truths in the Mineral Hiſtory.
