abundant; in its native state it is mostly alloyed with arsenic, it is also found combined in the ores of silver, iron, cobalt, and zinc. The principal use made of this metal is for alloys, also as an ingredient in soft solders, being one of the most fusible of metals: a preparation of bismuth is sometimes used by painters in water colours; on paper it has a bluish tinge, but, like arsenic, becomes blackish on exposure to the air, and particularly if the air be impregnated with any fœtid or offensive effluvia. 15. Cobalt. The weight of this metal is about eight times that of water; its colour is grey with a tinge of red, and it is very difficult of fusion. Cobalt is not found pure; its ores being sometimes combined with arsenic and sulphur, or arsenic and iron, and accompanying the ores of copper, silver, arsenic, and bismuth. It is brought to this country reduced to an oxyde of a most brilliant blue colour, called zaffre, which, when melted with three parts of sand and one of potash, forms blue glass: this reduced to a fine powder is known by the name of smalts, and is used for giving a blue tinge to various substances, as paper, cloth, linen, muslin, &c.; likewise in painting on porcelain, and also in oil and water. 16. Manganese. Manganese is about seven times heavier than water; its colour is a rusty grey; it is brittle, in a slight degree malleable, and is never found pure. The ores of this metal are frequently met with in mineral countries, and, in a state of oxyde, is found combined with a very considerable number of earthy and mineral substances. The black oxyde of manganese affords all the oxygen used by the chemist, and likewise the oxygen in the composition of the oxymuriatic acid, so essential to the bleacheries of Europe. It is also used in glass-making, and a beautiful violet colour is obtained from it, which is employed in painting porcelain. 17. Tellurium. This is a rare metal, it is about six times heavier than water; is very fusible, brittle, and of the colour of tin. Tellurium is found in a metallic state, but always alloyed by some other metal, as gold, lead, copper, &c. 18. Titanium. This metal is of a reddish copper colour, and so extremely difficult of fusion, that attempts to reduce it to a pure metallic state have rarely succeeded. It is found combined with oxyde of iron, manganese, silex, &c.; it was formerly employed in painting on porcelain, but has fallen into disuse from the want of uniformity in its colour. 19. Tantalium is a very rare metal; it is about six times heavier than water; its external surface has a slight metallic lustre, but the interior is dull and nearly black. Tantalium has only been found in Sweden and Finland, combined with the oxydes of iron and manganese, as also with the rare earth Yttria. 20. Molybdena. Like the last this is exceedingly rare, has never been found pure, and is with difficulty reduced to a pure state, having only been obtained in brittle infusible grains. It is found in a mineral state combined with sulphur, and in the acid state with lead. 21. Tungsten. This is a hard, brittle, granular metal, of a light steel grey colour, and brilliant metallic lustre. It is found combined with oxyde of iron, manganese, and silex, and occurs in most places abounding with tin: it has been used with other substances in the formation of red colours known by the name of lakes. 22. Chrome. This substance has never been found in a metallic state, only entering into the composition of some few substances: the emerald is supposed to owe its brilliant green colour to its combination with this rare metal. 23. Rhodium. This metal is not malleable; it possesses à bright metallic lustre, and is about eleven times heavier than water. 24. Osmium is of a dark grey colour. 25. Iridium, when pure, is white and infusible. The three last named metals are very rare, having only been found alloying the native platina of Peru, and have not been applied to any useful purpose. 26. Uranium has never been found in a metallic state; its colour is dark grey, its substance is brit tle, and may be cut with a knife; it is the lightest of all metals excepting tellurium, being only six times heavier than water. It has not been applied to any use. 27. Cerium. This, like the last, has never been found in a metallic state, and has only been obtained with considerable difficulty by the chemist: it enters into the composition of a few rare minerals. For some useful hints to collectors of minerals, see the Naturalist's Pocket Book, p. 323. To the student in Mineralogy, who wishes for a popular and intelligible guide, we have no hesitation in recommend ing Mr. Phillips's Outlines of Mineralogy, 12mo, 2d edition; Outlines of Mineralogy and Geology, by the same author; and Aikin's Manual, all of them excellent publications. Mr. PARKINSON's Organic Remains of a former World' are an inexhaustible fund of instruction and delight to the geologist and mineralogist. This grand work is a unique in these departments of science, and is as remarkable for the deep and learned research which it displays, as for the beautiful and highly accurate engravings with which it is embellished. It is a national ornament; and resembles more the splendid works that have issued from the continental press, under imperial patronage, than a book produced by the unassisted, but unremitted, exertions of an individual—an active member, too, of a harassing and laborious profession. We shall conclude this Introduction with some reflections on the pleasing nature of the study of mineralogy. The wonderful form of common salt, the precious stones, the singular shapes of the ores or metals in their mineral state, the astonishing particulars relative to extraneous fossils, and a variety of inexhaustible objects of inquiry in the mineral kingdom, seem eminently constituted to excite our curiosity. Were we to live for ages in this world, and to employ every day in studying the singularities of the mineral kingdom only, we should still find innumerable objects which we could not explain, which would stimulate more and more our researches, and yet continue inscrutable by our finite capacities. Let us well employ, then, the short time that is granted to us here, and devote as much of it as the necessary duties of life will permit to the study of Nature; and, by thus enriching our minds, treasure up the most innocent and the most inexhaustible stores of knowledge and pleasure. The exquisite delight which such studies afford will be still further heightened in proportion as we meditate on the ends which the Creator has proposed in his works; for the wonders of Nature are far above every, the most admirable, production of human art. These are not always compatible with our welfare; and, so far from rendering us either wiser or better, they are often the mere objects of uninstructive admiration. But all the works of Nature, even the most singular and inexplicable, have for their object the felicity of the whole creation. They exist, not merely to be contemplated as objects of sight, but to be enjoyed; and all, without exception, proclaim unspeakable goodness, as well as unsearchable wisdom and unbounded power. Oh, NATURE, all-sufficient, over all! Enrich me with the knowledge of thy works! Profusely scattered o'er the blue immense, Show me; their motions, periods, and their laws, A search the flight of time can ne'er exhaust! THOMSON. |