MINERAL KINGDOM.

LEAD.

LEAD is a meta very anciently known; it is often mentioned by Moses. Its alchemical name was Saturnus. It is of a considerably blue tinge, very soft and flexible, not very tenacious, and consequently incapable of being drawn into fine wire, though it is easily extended into thin plates under the hammer-when recently cut it has a strong metallic lustre, but it soon tarnishes from exposure to the air. It soils paper and the fingers, imparts a slight taste, and emits, by friction, a peculiar smell. Its specific gravity is 11.358. It is a good conductor of heat, melts at 612° Fahr. and, when cooled, slowly crystallizes in quadrangular pyramids. It is brittle at the time of congelation. In this state it may be broken to pieces with a hammer, and the crystallization of its internal parts will exhibit an arrangement in parallel lines. Most of the acids attack lead. The sulphuric does not act upon it, unless it be concentrated and boiling. Nitric acid acts strongly on lead. Muriatic acid acts directly on lead by heat, oxidizing it, and dissolving part of its oxide. White lead, or ceruse, is made by rolling leaden plates spirally up, so as to leave a space of about an inch between each coil, and placing them vertically in earthen pots, at the bottom of which is some good vinegar. This, like all the preparations of lead, is a deadly poison. Lead may be mixed with gold and silver, in a moderate heat, but when the heat is much increased, the lead rises to the surface, combined with all heterogeneous matters. Upon this property of lead is built the art of refining the precious metals. If melted lead be exposed to the atmosphere, a greyish-yellow powder begins to form upon the surface, called common massicot; and by a higher heat, and longer exposure to the air, it assumes a deeper yellow, and is then called massicot, or YELLOW OXYD OF LEAD. By a second exposure this oxyd appears capable of combining with more oxygen. It gradually changes color and ulti

mately assumes a splendid red. In this state it is called minium, or RED LEAD. If the heat be too great or rapid the lead becomes converted into a flaky substance, called litharge. The common sugar of lead is an acetate, and Goulard's extract, made by boiling litharge in vinegar, is a subacetale. The power of this salt as a coagulator of mucus, is superior to that of the other. If a plate of zinc be suspended by a thread, in a solution of acetate of lead, the lead will be revived, and form an arbor saturni. The acetate or sugar of lead, is usually crystallized in needles, which have a silky appearance. The proper counterpoison of a dangerous dose of sugar of lead, is a solution of Epsom or Glauber salts, liberally swallowed; either of which medicines instantly converts the poisonous acetate of lead into the inert sulphate. Sugar has been found to neutralize the poisonous action of acetate of lead, and therefore may be regarded as an excellent antidote to it.

ORES OF LEAD.

Ores of lead occur in great abundance in a most every part of the world. They are generally in veins, sometimes in siliceous rocks, sometimes in calcareous rocks. Nearly all the lead of commerce is obtained from galena, the sulphuret of lead, which is found both in masses and crystallized. There exists however, but a single ore of lead, which ever occurs in sufficient quantity by itself to justify its exploration-that ore is the sulphuret. It constitutes beds and veins, both of which are sometimes very extensive. In England it is very abundant. It is widely dispersed over the United States. The mines of Missouri and of the Northwestern Territory, are very rich. The deposite of galena in which the mines of Missouri are situated, is evidently one of the most extensive and important hitherto discovered. Carbonate of lead, or white lead ore, so called from its prevailing color, like all the salts of lead, is perfectly unmetallic in its appearance, and is not unfrequently rejected from among common lead ore, as an earthy mineral. This species often occurs massive, and intermingled with earth and metallic oxides, and is sometimes tarnished and blackened, so as to be

with difficulty recognised. It is pretty abundant in European countries, but has been found very sparingly in the United States. Sulphate of lead occurs, but not very plentifully, in the Hart, Spain, England, and Scotland. Chromale of lead is of a deep orange-red color; when pulverized, orange-yellow. It has hitherto been found only in Siberia, where it occurs in a vein traversing gneiss and mica slate in the gold mine of Beresof. Molybdate of lead occurs principally at Bleiberg in Carinthia, with other ores of lead. It has also been found in very small quantity, at South Hampton, Massachusetts. Phosphate of lead is found accompanying the common ores of lead, though rarely in any considerable quantity. Finely crystallized varieties are found at Przibram in Bohemia, at Huelgoet in Brittany, at Lead-hills in Scotland, and at Cornwall in England. In the United States it occurs at the lead mine near Freyburg in Maine. Such are the ores of lead, all of which, with the exception of the chromate, are more or less employed in furnishing the lead of commerce, but the salts, as has been remarked above, in very limited quantity compared with the sulphuret. England produces about half the lead of Europe; the Hartz, Austria, Prussia, and their dependencies nearly all the remainder. The lead mine of Galena, in Illinois, yielded in 1829, about six thousand tons of lead. The annual product of all the lead mines of Great Britain is about forty-six thousand tons.

It is certain that both lead and tin were employed, in extremely remote ages, in the fabrication of arms, and above all, in the ornamental parts of them. Homer alludes to the practice of putting leaden balls at the end of fishing lines. The custom of writing on lead mounts also into very great antiquity. Frontinus and Dio Cassius assure us that the consul Hirtius, besieged in Modena, wrote upon a leaf of lead, respecting his situation to Decius Brutus, who replied by the same means. Pausanias speaks of certain books of Hesiod written upon sheets of lead, and Mountfaucon assures us, that in 1699 he bought at Rome, a book entirely of lead, four inches long by three inches wide. From Job xix. 24, it appears to have been usual

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in his day to write or engrave upon plates of lead. cording to Pliny, even public acts were consigned to volumes or leaves of the same material. The poets make frequent allusion to leaden coins. Statues of lead are very rare.

FAMILIAR ILLUSTRATIONS OF NATURAL PHENOMENA.

THE GREAT CURRENT OF THE ATLANTIC, CALLED THE GULF STREAM.

PERSONS are often prevented from inquiring into a subject, under the impression that it is too difficult for them to comprehend; when a very little attention would render it very easy.

Every body, who has observed the stream rushing through a mill-dam into a wide basin of water, must have noticed, that a great part of the water is in a state of constant circulation. If a chip of wood is thrown into the current, it is carried away at first very rapidly, but afterwards gets to the edge of the stream, takes a circuit, and is possibly brought back nearly to the place where it was first thrown in. This revolving motion of the water is thus occasioned: the water next to that in the stream is dragged along with it; the removal of this causes a hollow, into which the water next to it runs; and this kind of motion is thus propagated throughout all the mill-pool.

Now this represents, on a small scale, a great natural phenomenon, called the Gulf Stream, because it was first observed in the Gulf of Florida, in the Atlantic Ocean. That particular current, however, is only part of an extensive circulation of all the waters in the great western basin.

To understand this, it must be observed, that the waters of the open ocean, between the tropics, have a constant motion from east to west. This is seen very evidently at the Cape of Good Hope, where the waters of the great Indian Ocean unite with the Atlantic. There is a con