* Fell Giesar roar'd. l. 150. The boiling column of water at Giesar in Iceland was nineteen feet in diameter, and sometimes rose to the height of ninety-two feet. On cooling it deposited a siliceous matter or chalcedony forming a bason round its base. The heat of this water before it rose out of the earth could not be ascertained, as water looses all its heat above 212 (as soon as it is at liberty to expand) by the exhalation of a part, but the flinty bason which is deposited from it shews that water with great degrees of heat will dissolve siliceous matter. Van Troil's Letters on Iceland. Since the above account in the year 1780 this part of Iceland has been destroyed by an earthquake or covered with lava, which was probably effected by the force of aqueous steam, a greater quantity of water falling on the subterraneous fires than could escape by the antient outlets and generating an increased quantity of vapour. For the dispersion of conta∣gious vapours from volcanos see an account of the Harmattan in the notes on Chunda, Vol. II.
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