Cxi NOTES. 



described by Chisholm, and the showers of ashes of August 5, 1851, deserve to 

 be more closely inquired into. 



The Soufriere de la Guadeloupe, according to the older measurements of Amic 

 and Le Boucher 5435 and 5109 feet high, but according to the most recent and 

 very exact ones of Charles Sainte-Claire Deville only 4867 feet high, showed 

 itself to be a pumice-ejecting volcano on the 28th of September 1797, seventy- 

 eight days therefore before the great earthquake and the destruction of the town 

 of Cumana. (Rapport fait au Ge'neral Victor Hugues, par Amic et Hapel, sur 

 le Volcan de la Basse Terre, dans la nuit du 7 au 8 veude'iniaire, an 6, p. 46 ; 

 Humboldt, Voyage, t. i. p. 316.) The lower part of the mountain is of dioritic 

 rock; the volcanic cone whose summit is opened is trachyte containing labra- 

 dorite. The mountain, which, on account of its ordinary condition, is called the 

 Soufriere, never appears to have sent forth lava in streams, either from the 

 summit-crater, or from lateral fissures; but the ashes of the eruptions of Sept. 

 1797, Dec. 1836, and Feb. 1837, examined by the excellent and lamented 

 Dufre'noy with the accuracy which characterised him, were found to consist of 

 finely triturated fragments of lava, in which felspathic minerals (labradorite, 

 rhyakolite, and sanidine), together with pyroxene, were recognised. (See Lher- 

 minier, Daver, Elie de Beaumont, and Dufre'noy, in the Comptes rendus de 

 1'Acad. des Sc, t. iv. 1837, p. 294, 651, and 743749.) Also Deville re- 

 cognised in the trachytes of the Soufriere small fragments of quartz, together 

 with labradorite crystals (Comptes rendus, t. xxxii. p. 675); as Gustav Rose 

 did hexagonal dodecahedrons of quartz in the trachytes of the Volcano of 

 Arequipa. (Meyen, Reise urn die Erde, Bd. ii. S. 23.) 



The phenomena here described, of the ejection, during a period of short con- 

 tinuance, of very various mineralogical substances from the fissured apertures of 

 a Soufriere, remind us forcibly that what we commonly call solfataras, soufrieres, 

 or fumaroles, are, strictly speaking, only the indications of certain states of vol- 

 canic activity. Volcanoes which once poured forth lavas, or, failing these, ejected 

 unconnected scorise of considerable bulk, or lastly, the same scorias reduced by 

 friction to a state of powder, in a later stage of diminished activity arrive at a 

 condition in which they furnish only sulphur sublimates, sulphurous acid, and 

 aqueous vapour or steam. If we were to call them in this state semi- volcanoes, 

 we might be likely thereby to give occasion to the idea of their being a peculiar 

 class of volcanoes. Bunsen to whom, together with Boussingault, Senarmont, 

 Charles Deville, and Daubre'e, science is indebted for such valuable advances 

 obtained by the ingenious and happy application of chemistry to geology, and 

 more especially to volcanic processes has shown the manner in which, when 

 in sublimations of sulphur, which almost always accompany volcanic eruptions, 



