Being intended for the Young, this work treats of Volcanoes only in a popular way. Scientific details and philosophical speculations are accordingly avoided. Nevertheless, a perusal of the following pages may so stimulate the curiosity of youthful minds, that some, on attaining to riper years and more mature understanding, may be inspired with a longing to inquire more deeply into this interesting subject.
d, differ much in their appearance and composition. Among those of Iceland is found the beautiful black volcanic glass named obsidian. It is a good deal used for ornamental purposes; for it possesses the peculiar property of presenting a different appearance according to the manner in which it is cut. When cut in one direction it is of a beautiful jetty black; when cut across that direction it is glistering gray. The lavas of Vesuvius are generally of a brown colour, and are also used in the arts. In them are found the beautiful olive-green crystals of the mineral called olivine, sometimes used by jewellers. But the most useful of all volcanic productions is native sulphur, in which Mount Etna has been very prolific. It is to this mountain chiefly, therefore, that we are indebted for our beautiful fire-works--our squibs, crackers, Roman candles, serpents, Catherine-wheels, and sky-rockets. Would it had produced nothing more harmful than these! But it has also supplied one of the ingredients of that villainous