The specific gravity of the specimen from Vicdessos was 3.4.

Fifth species.-Brown scaly iron ore. Braun eisen ram of Werner.-Its color is intermediate between the tomback or nut-brown, and steelgray. Generally found incumbent on other fossils, sometimes detached, imperfectly rounded or branchy. Lustre from 1 to 2. Metallic. Fracture seems fine-foliated or scaly, passing into the even. Fragments 1, 2. Hardness from 3 to 5. Brittle; light, so as often to float on water. Stains the fingers, or marks strongly, feels somewhat unctuous. From its lightness some have called it eisen bluthe. Before the blow-pipe it blackens, and gives to borax a greenish-yellow color.

Sixth species.-Brown iron ochre. Ockriger braun eisen stein of Werner.-Its colors extend from the nut-brown to the ochre-yellow, and orange. Found massive and disseminated. Transparency 0. Lustre 0. Fracture earthy Hardness from 3 to 4. Strongly stains the fingers. When slightly heated it reddens. Before the blow-pipe it blackens, and gives borax a yellowish or olive-green color.

Seventh species. Red hæmatites rother glass kopf of Werner.-Color between brownish-red and dark stell-gray. Massive, imitative, and in supposititious double six-sided pyramids from calcareous spar. Glistening, semi-metallic. Opaque. Streak blood-red. Brittle. Specific gravity 4.74. Its constituents, according to D'Aubuisson, are 90 oxide of iron, silica 2, lime 1, water 3. It affords excellent malleable and cast iron. Its powder is used for polishing tin, silver, and gold vessels; and for coloring iron brown. Baron Born assures us, it is often mixed with calcareous earth, and then effervesces with acids. The baron and Bergman also mention a yellow hæmatites, which differs from this only in presenting a yellow powder when pulverised.

It occurs generally in veins in primitive and transition mountains, accompanied with other ores of iron, copper, pyrites, quartz, barytic spar, &c. Although a rare variety of this metal, it is found rather plentifully in the neighbourhood of Ulverston, Lancashire, and is also met with in Cornwall. It occurs too in Norway, the Hartz, Saxony, Silesia, Salzburg, Hungary, and South America.

Eleventh species.-Upland argillaceous iron ore. Gemeiner thonartiger eisen stein of Werner.-Color, steel, reddish or yellowish-gray, or yellowish and dark nut brown, or dark brick-red, or dark ochre yellow. The gray becomes blacker by exposure to the air.

On an ore of this kind, the celebrated iron foundries of Carron in Scotland are principally founded. Its color is partly light, partly dark bluish gray: some specimens are also of a light, or whitish purple externally, but internally dark ochre yellow. It is found in masses, apparently slaty, and in nodules in an adjacent coal mine, of which it sometimes forms the roof. Lustre 0.1. Transparency 0. Cross fracture, compact, uneven, or imperfectly conchoidal, longitudinal, even. Fragments 2. Hardness Eighth species.-Compact red iron stone, Dich- from 5 to 6. Specific gravity of light gray, ter roth eisen stein of Werner.-Color between found by Dr. Rotheram, before calcination, dark steel-gray and blood-red. Massive, and in 3434; after calcination, 3.652. Of the dark supposititious crystals; which are an acute gray, before calcination, 3.205; after calcination double six-sided pyramid from calcareous 4.190. spar; Of the yellowish, before calcination, and a cube from fluor spar and iron pyrites. 3.357. Streak of the light gray, dark red. Of Lustre metallic. Fracture even. Streak pale the yellowish, yellow. It gives out no smell blood red. Easily frangible. Specific gravity when breathed on. It affords about thirty per 4.232. When pure it does not affect the magnet. Its constituents are, oxide of iron 70.5, oxygen 29.5. Of this sort is the Lancashire ore, sometimes used at Carron, in Scotland. Externally it is invested with a rosy red ochre ; internally its color is a purplish-gray.

Ninth species. -Red ochre, ockriger roth eisen stein of Werner.-Its color blood-red, more or less dark. It is found sometimes loose, sometimes indurated. Lustre 0. Fracture earthy, sometimes slaty. Hardness from 3 to 4. Brittle. Rarely 5. Stains the fingers. Heated, it blackens. It does not effervesce with acids, unless mixed with mild calx, as it often is in England. Specific gravity 2.947. It occurs in veins, with the preceding ore. It melts more easily than any of the other ores of this metal, and affords excellent malleable iron.

Tenth species.-Red scaly iron ore, Rother cisen ram of Werner.-Color dark steel-gray to

cent. of cast iron.

Some specimens of the mineral yield as much as forty per cent. of oxide of iron, whilst others do not afford more than twenty per cent., and many even less than that. The following are the results of some analyses by Richter and Lampadius:

It occurs in nests in clay beds, amongst bog iron ore, and incrusting turf and peat. It is found, under the latter circumstances, in the Shetland Islands; it also appears in Iceland, Saxony, Silesia, Suabia, Bavaria, Poland, Siberia, Russia, and Sweden.

Nineteenth species.-Green martial earth. Grüne eisenerde of Werner. Color light or dark canary green, and thence passing into the olive green or yellow. Commonly found investing, or incumbent. Friable: seldom indurated. Lustre 0. Fracture nearly even. Hardness from 3 to 6. Strongly marks the fingers. Not remarkable heavy. Streak gray. Difficultly soluble in acids. When strongly heated it loses its weight, and blackens. With borax it easily melts into a yellowish brown opaque glass, with black spots.

No exact analysis has been made of this species; but it is supposed by Werner to have iron and phosphoric acid for its principal ingredients.

It is a rare mineral, and has hitherto been only found at Braunsdorf and Schneiberg, in Saxony, where it occurs in veins in the former place accompanied with quartz and pyrites, and in the latter with quartz and native bismuth. Twentieth species.—Common pyrites. Gemeiner sulphur kiess of Werner: color bronze yellow inclining sometimes to gold-yellow occurs massive and disseminated in minute cubes, octohedrons, dodecahedrons, and sometimes though very rarely icosahedrons are met with. External lustre 4.3. Internal 2. Metallic. Transparency 0. Fracture uneven: fine or coarse grained. Hardness 10, brittle. Specific gravity from 2.9 to 4.6. It is not magnetic, and if rubbed yields a sulphureous smell. It decrepitates, and, when heated red hot, loses its fine yellow color and becomes of an iron gray and partly of a bright red. At 102, of Wedgewood's pyrometer, it melts in a covered crucible into a bluish-gray slagg, somewhat porous internally. Before the blow-pipe it emits a strong sulphureous smell, burns at first with a blue flame, and leaves a brownish bead, which tinges borax of a smutty green otherwise, if further heated, it reddens. Its occurrence is almost universal, both with respect to geographic arrangements, and the numeral formations in which it is presented.

Twenty-first species.-Striated pyrites: strahl kiess of Werner. Color when fresh broken similar to those of the former variety, but more liable to be tarnished, passing into variegations resembling those of a peacock's tail. Found reniform, stalactitic, or crystallised in small cubes, or pyramids united in a common basis, generally grouped together, and implicated in each other. External lustre, when undecayed, 3.4. Metallic. Internal 2. Transparency 0. Fracture sometimes coarse and broad, sometimes fine and striated. Fragments present curved lamellar distinct concretions turned inwards. Hardness 10. Brittle. Specific gravity from 3:44 to 4.1. Brisson. Before the blow-pipe it exhibits the same appearances as common pyrites, and is constituted of about fifty-four parts of sulphur, and forty-six of iron.

It is considerably more rare than the preceding and is found in veins, particularly those which contain lead or silver.

The chief places of its occurrence are, Cornwall and Derbyshire, in England; Arendal, in Norway; and in various districts of Suabia, Saxony, and Bohemia.

Twenty-second species.-Capillary pyrites, haarkiess of Werner. Its color generally steel gray, or intermediate between that and the pale yellow. Found in hexangular, or octangular, acicular crystals, either parallel or diverging from a common centre, or capillary and woolly, or interwoven. Lustre 3. Metallic. Transparency 0. This variety is the least common of the pyrites. Hydro-oxide of iron.

Twenty-third species.—Magnetic pyrites: magnetischer eisen kiess of Werner. Color intermediate between the tombac brown, and brass yellow. Often iridescently tarnished. Found disseminated and massive. Lustre 2. Metallic. Transparency 0. Fracture compact, inclining to the small conchoidal and uneven. Fragments 2. Hardness 8.9. Brittle. Specific gravity exceeds 3. Slightly magnetic : when treated with the blow-pipe, it does not give out so strong a smell of sulphur, but melts into a grayish-black bead, which is also magnetic; with borax it effervesces, and gives it a black tinge. It is composed of 63.5 sulphur and 36.5 iron.

Twenty-third species.- Hepatic pyrites. Leber pyrites of Werner. Wasser kiess of others. Color steel gray or intermediate between steel gray and pale yellow, sometimes variously tarnished by exposure to the air. It occurs massive or disseminated, or stalactitic, reniform, cellular, orbicular, tabular, &c. Its surface often striated. External lustre 2. Internal 1. Metallic. Transparency 0. Fracture even, uneven, or inclining to the conchoidal. Hardness from 9 to 10. Specific gravity from 3477 to 3502. Lustre of its streak 2.3. Exposed to air and moistened, it does not effloresce.

Its

Twenty-fourth species.-Calcareous or sparry iron ore. Spath eisin stein of Werner.-Color nearly white, passing into yellowish-brown, and blackish-brown. It tarnishes on exposure either to the air or heat, and then becomes brown or black, and sometimes iridescent. It is found massive, disseminated, and crystallised. crystals are either rhombs, octahedrons, or dodecahedrons. They are seldom large; commonly middle-sized and small. Their surface is generally smooth. Internally it varies from splendent to glimmering. Lustre pearly. Fracture foliated. Cleavage triple. Fragments rhomboidal. The light-colored varieties are translucent, especially on the edges; but the dark-colored, opaque. The former give a grayish-white streak; the latter a yellowish-brown. It is semi-hard, inclining sometimes to soft. Rather brittle. Easily frangible, and moderately heavy. Specific gravity 3.300 to 3.810. Not magnetic. Carbonate of iron.

It blackens before the blowpipe, and enters into ebullition with borax, to which it communicates a dirty yellow color. It always effervesces more or less with acids. According to Bergman, it is composed of

acid affords a more permanent solution of iron, of a greenish color, or sometimes of a yellow color. Neither of the solutions affords crystals, but both deposit the oxide of iron by boiling, at the same time that the fluid assumes a gelatinous appearance.

silver, and platina. When heated to a white heat, and plunged in mercury, it becomes co vered with a coating of that metal. Mr. A. Aikin unites an amalgam of zinc and mercury with iron filings, and then adds muriate of iron, when a decomposition takes place, the muriatic acid combining with the zinc, and the amalgam of iron and mercury assuming the metallic lustre by kneading, assisted with heat. Iron and tin very readily unite together. Iron does not unite easily with bismuth, at least in the direct way. This alloy is brittle and attractible by the magnet, even with three-fourths of bismuth. As nickel cannot be purified from iron without the greatest difficulty, it may be presumed that these substances readily unite. Arsenic forms a brittle substance in its combination with iron. Cobalt forms a hard mixture with iron, which is not easily broken. Manganese is almost always united with iron in the native state. Tungsten forms a brittle, whitish-brown, hard alloy, of a compact texture, when fused with white crude iron. The habitudes of iron with molybdena are not known.

Diluted muriatic acid rapidly dissolves iron at the same time that a large quantity of hydrogen is disengaged, and the mixture becomes hot. If iron filings be triturated with muriate of ammonia, moistening the mixture; then drying, powdering, and again triturating; and lastly subliming with a heat quickly raised; yellow or orange-colored flowers will rise, consisting of a mixture of muriate of ammonia, with more or less of muriate of iron. These, which were called flowers of steel, and still more improperly ens veneris, were once much esteemed; but are now little used, as they are nauseous in solution, and cannot very conveniently be given in any other form. Carbonic acid, dissolved in water, combines with a considerable quantity of iron, in proportion to its mass. Phosphoric acid unites with iron, but very slowly. The union is best effected by adding an alkaline phosphate Dr. Wollaston first showed, that the forms in to a solution of one of the salts of iron, when it which native iron is disposed to break are those will fall down in a white precipitate. This acid of the regular octohedron and tetrahedron, or is found combined with iron in the bog ores, rhomboid, consisting of these forms combined. and, being at first taken for a peculiar metal, In a specimen possessed by this philosopher the was called siderite by Bergmann. Liquid fluo- crystalline surfaces appear to have been the reric acid attacks iron with violence: the so- sult of a process of oxidation which has penelution is not crystallisable, but thickens to a jelly, trated the mass to a considerable depth in the diwhich may be rendered solid by continuing the rection of its laminæ ; but, in the specimen which heat. The acid may be expelled by heating it is in the possession of the Geological Society, strongly, leaving a fine red oxide. Borate of the brilliant surfaces that have been occasioned iron may be obtained by precipitating a solution by forcible separation from the original mass of the sulphate with neutral borate of soda. exhibit also the same configurations as are usual Arsenic acid likewise unites with iron, This in the fracture of octohedral crystals, and are arseniate is found native. Chromate of iron has found in many simple metals. This spontaneous been found in the department of Var in France, decomposition of the metal in the direction of and elsewhere. Sulphur combines very readily its crystalline laminæ is a new and valuable fact. with iron. A mixture of iron filings and flowers From Mr. Daniell's ingenious experiments on of sulphur being moistened, or made into a paste the mechanical structure of iron, developed by with water, becomes hot, swells, adheres together, solution, we learn, that a mass of bar-iron which breaks, and emits watery vapors of an hepatic had undergone all the operations of puddling smell. If the mixture be considerable in quan- and rolling, after being left in liquid muriatic tity, as for example 100 lbs., it takes fire in acid till saturation, presented the appearance of twenty or thirty hours, as soon as the aqueous a bundle of fasces, whose fibres run parallel vapors cease. By fusion with iron, sulphur through its whole length. At its two ends, the produces a compound of the same nature as the points were perfectly detached from each other, pyrites, and exhibiting the same radiated struc- and the rods were altogether so distinct, as to apture when broken. If a bar of iron be heated to pear to the eye to be but loosely compacted. whiteness, and then touched with a roll of sul- Compounds of iron. phur, the two substances combine, and drop down together in a fluid state. Mr. Hatchett found, that the magnetical pyrites contain the same proportion as the artificial sulphuret. Phosphorus may be combined with iron by adding it, cut into small pieces, to fine iron wire heated moderately red in a crucible; or by fusing six parts of iron clippings, with six of glacial phosphoric acid, and one of charcoal powder. This phosphuret is magnetic; and Mr. Hatchett remarks, that iron, which in its soft or pure state cannot retain magnetism, is enabled to do so when hardened by carbon, sulphur, or phosphorus, unless the dose be so great as to destroy the magnetic property, as in most of the natural pyrites and plumbago. Iron unites with gold,

1. Oxides; of which there are two, or perhaps three. 1st. The oxide obtained either by digesting an excess of iron filings in water, by the combustion of iron wire in oxygen, or by adding pure ammonia to solution of green copperas, and drying the precipitate out of contact of air, is of a black color, becoming white by its union with water, in the hydrate, attractible by the magnet, but more feebly than iron. By a mean of the experiments of several chemists, its composition seems to be,

100

77.82

Iron
Oxygen 28.5 22.18

3.5
1.0

Whence the prime equivalent of iron comes out, we perceive, 3·5. Sir H. Davy's number, re