On the phenomena of volcanoes

• Published in: Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1833
• Subjects: Carbonic acid
• Online Access: http://dx.doi.org/10.1098/rspl.1815.0339; https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1815.0339

In a paper on the Decomposition of the Earths, published in the Philosophical Transactions for 1812, the author offered it as a conjecture that the metals of the alkalies and earths might exist in the interior of the globe, and on being exposed to the action of air and water, give rise to volcanic fire and to the production of lavas; by the slow cooling of which, basaltic and other crystalline rocks might subsequently be formed. Vesuvius, from local circumstances, presents peculiar advantages for investigating the truth of this hypothesis; and of these, the author availed himself during his residence at Naples in the months of December 1819, and of January and February 1820. A small eruption had taken place a few days before he visited the mountain, and a stream of lava was then flowing with considerable activity from an aperture in the mountain a little below the crater, which was throwing up showers of red-hot stones every two or three minutes. On its issuing from the mountain, it was perfectly fluid, and nearly white-hot; its surface appeared to be in violent agitation, from the bursting of numerous bubbles, which emitted clouds of white smoke. There was no appearance of more vivid ignition in the lava when it was raised and poured out by an iron ladle. A portion was thrown into a glass bottle, which was then closed with a ground stopper; and on examining the air in the bottle some time afterwards, it was found not to have lost any of its oxygen. Nitre thrown upon the surface of the lava did not produce such an increase of ignition as would have attended the presence of combustible matter. The gas disengaged from the lava, proved on examination to be common air. When the white vapours were condensed on a cold tin plate, the deposit was found to consist of very pure common salt; and the vapours themselves contained 9 per cent, of oxygen, the rest being azote, without any notable proportion of carbonic acid or sulphurous acid gases; although the fumes of this latter gas were exceedingly pungent in the smoke ...