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yttria, and phosphates of alumina, as wavellite, arurite, the calaite or real turquois from Persia,' &c.

[57 A.] Phosphates combined with chlorides. Pyromorphite; arseniates of lead, &c.

[57 B.] Phosphate of lime combined with chloride of calcium. Rare crystallizations of apatite. Chloro-carbonate of lead. The unique suite of crystals is from Cromford Level, near Matlock Dale, Derbyshire.

8. [4.] Native arsenic, with nickel and with cobalt. In the opposite half of this case, substances belonging to the orders carbon and selenium. Diamonds; several illustrations of the various crystalline forms of this pure state of carbon; diamonds imbedded in siliceous breccia, in compact brown ironstone; and a specimen of the alluvial rock called cascalhao, in which diamonds occur in the East Indies and the Brazils. Anthracite. Graphite. Seleniurets of lead, copper, mercury, cobalt, &c. Sulphur from the Lipari Isles. A medallion in selenium of Berzelius, the discoverer of this metal.

9. [56.] Arsenious acid, and arseniates of lime, iron, copper, cobalt, nickel, &c.

10. [5.] Splendid crystallisations of sulphur from La Catolica in Sicily. These are succeeded by the sulphurets, which occupy half of this, and seven of the next following table cases, according to the museum notation. Sulphuret of manganese, zinc or blend, &c.

11. [55.] Sulphates of magnesia, zinc, iron, copper, lead, &c. Sulphate of uranium, oxide or johannite, very rare, from Bohemia. Sulphates of alumina. Websterite from Sussex and Halle. Beautiful series of examples of lazurite or lapis lazuli.

12. [6.] Sulphurets of iron, or iron pyrites. Sulphuret of cobalt, of nickel, of cadmium, &c.

1 The oriental turquois is an hydrate of aluminum coloured by oxide of copper and iron; it is found in amorphous masses in alluvial clay, and in irregular veins in flinty slate, in Persia and Siberia. The common or accidental turquois is fossil ivory or bone stained by blue phosphate of iron or carbonate of copper.




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Vegetable remains occur in the mineral kingdom in various states of preservation, and under very different conditions; in some cases, they are but little changed in aspect and composition; in others, they are so completely metamorphosed that their vegetable nature can only be detected by the aid of the microscope. It will suf fice for our present purpose to consider two principal states in which the fossil remains of trees and plants are preserved.

1st. Petrified Vegetables: In this state the organic structure is permeated by mineral matter, and oftentimes the original vascular tissues are transmuted into stone: it may be calcareous, as in some of the fossil woods from the Lias; or siliceous, as in the wood from New Holland, and the palm-stems from Saxony; or partly calcareous and partly siliceous, as the trees from the Isle of Portland, &c. Iron is a frequent constituent in the petrifaction of vegetable substances; and the sulphuret, or iron pyrites, is very constantly present in wood, fruits, leaves, &c., imbedded in argillaceous deposits; often imparting a most beautiful metallic lustre to the organic structures, as in the fossil fruits from the Isle of Sheppey.

2d. Carbonized Vegetables: The other state in which vegetable substances are found is that of carbonization-that peculiar transmutation which dead vegetable structures undergo when buried in the earth, and subjected to heat and moisture a specific fermentation or putrefaction (the bituminous) then takes place, and either bog-wood, lignite, brown coal, jet, or true mineral coal, containing combustible oils, is the result, accordingly as the necessary conditions are more or less perfectly fulfilled; for the formation of coal appears to depend on the engulfing of large quantities of recent vegetable substances beneath deposits of clay, mud, silt, and sand, which shall exclude the air, and prevent the escape of the gaseous elements, when released by decomposition from their organic combination. Such has been the origin of the immense accumulations of fossil fuel, or coal, in various parts of the world; and of the delicate fern-leaves and other foliage, which appear as pellicles or films of carbonaceous matter adherent to the surfaces of the slabs of slate and stone in the cases A, and B, before us these are the leaves of vegetables converted into carbon or charcoal ; some of these leaves even retain their flexibility, and may be removed from the surface, like the specimens in a hortus siccus.

COAL-But though the vegetable origin of all coal is unquestionable, yet evidence of the original structure of the plants or trees whence it was derived is not always attainable. The most perfect coal seems to have undergone a complete liquefaction, and if any portions of the vegetable tissues remain, they appear as if imbedded in a bituminous mass. The slaty coal generally preserves traces of cellular or vascular tissue, and the spiral vessels and dotted cells of coniferous trees may often be detected by the microscope. In many instances the cells are filled with an amber-coloured resinous substance; in others the organization is so well preserved, that on the surface of a block of coal cracked by heat, the dotted glands may be observed. Some beds of coal are wholly composed of minute leaves or disintegrated foliage, and if a mass recently extracted from the mine be split asunder, the exposed surfaces will be found covered with delicate lamina of carbonized leaves and fibres matted together, and flake after flake may be peeled off through a thickness of many inches.

Rarely are any large trunks or branches of trees observable in the beds of coal; the general appearance of the carboniferous mass is that of an immense deposit of delicate foliage which has been shed and accumulated in a forest, and consolidated by great pressure, while undergoing that peculiar process by which vegetable matter is converted into carbon. In fine, a gradual transition may be traced from the peat-wood and submerged forests of modern times, in which leaves, fruits, and trunks of indigenous trees are preserved, to those vast deposits of mineral coal, formed by the bitumination of the now extinct plants and trees of the floras which flourished in the earlier ages of the globe.

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AMBER, JET, DIAMOND.- Table-cases 1, and 8.—Before describing the fossil plants whose stems, foliage, and fruit, are displayed in the wall-cases of this room, we must direct attention to the table-cases that contain a fine suite of specimens of Amber [60], Jet, and Diamond 8, [4], for these substances are unquestionably of vegetable origin.

Amber, so remarkable for its electrical properties, and so much in request for ornamental purposes, is a fossil resin, the product of an extinct species of pine (Pinus succinïfer), most nearly allied to Pinus abies, and P. picea, but essentially distinct. The Amber in the European markets is principally collected from the shores of the Baltic, between Memel and Konigsberg, being washed out of submerged beds of lignite, and thrown up on the strand by the waves. Amber is occasionally found on the eastern and northern shores of England. The forests of Amber-pines appear to have been situated in the south-eastern part of what is now the bed of the Baltic, in about 55° north latitude, and 37° to 38° east longitude, and were probably destroyed at the commencement of the diluvial period. Insects, spiders, small crustaceans, leaves, and fragments of vegetable tissue, are often imbedded in amber; and a few hairs and feathers of mammalia and birds have been detected: these organic bodies must have become immersed in this substance when it exuded from the trees in a soft or viscid state, for they are often preserved as fresh and beautiful as if recently embalmed in the liquid resin. Upwards of 800 species of insects have been discovered, chiefly Aptera, Diptera, Neuroptera, Coleoptera, Libellula, &c.; by far the greater part belong to extinct forms.

The vegetable remains comprise four species of pine, and species of cedar, cypress, juniper, yew; and of oak, poplar, beech, ash, &c.; and a few ferns, mosses, liverworts, confervæ, and fungi. The amber appears to have chiefly exuded from the root-stock, but also from the bark and the wood, as is the case with the Copal and Animé, which are resinous substances obtained from certain trees in India and America, and largely employed for varnish: these resins are often substituted for true amber, especially when they contain insects, &c.; but these are always of the existing indigenous species of the country. There are many examples of copal and animé, containing insects, placed in the case with genuine fossil amber, for comparison. The difference observable in the colour of the various species of amber, is attributable to accidental chemical admixtures.

Jet. This substance is so evidently wood in a carbonized state (many species showing coniferous structure), that it is only necessary to direct attention to the specimens in Case 1. Some of the most productive beds of this fossil in England are those in the Lias shale, near Whitby, in Yorkshire.

In this case there is an interesting example of Hessian brown lignite passing into bituminous coal.

Diamond.-In Case 8 [4] there are many varieties of the precious gem-the diamond-illustrating its varied colours. and crystalline forms; among these are diamonds imbedded in siliceous breccia, and in brown ironstone, and an octahedral crystal with alluvial gold; and models of some of the largest diamonds. The diamond, as is now generally known, is nothing more than carbon or charcoal in a pure crystalline state; of its vegetable origin there is no doubt. At a heat less than the melting point of silver it burns and is volatilized, yielding the same elementary products as charcoal. By voltaic action it has been converted (by Jacquelin, Faraday, Gassiott) into a substance possessing the appearance, physical characters, and electrical properties of coke or graphite, losing its insulating power, and becoming a conductor: its ordinary specific gravity is 3.368; when changed into coke, 2.679. The diamond, like amber, is probably a vegetable secretion, and has acquired its crystalline structure by electro-chemical action. In Southern India and in the

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