Class IV-Metals Proper:-All the remaining metals.

The metals are mostly found in the bowels of the earth, in what are called veins (from the Latin, vena), excepting iron, which occurs in strata. A vein is a fissure or rent, filled with mineral or metallic matter, differing from the rock in which it occurs. The word strata, the plural of stratum (from the Latin, sterno, I spread), is applied to layers in which the rocks lie one above another. The metals are obtained by penetrating from the surface of the earth to the vein, and there following it in whatever direction it may lie. The hollow places thus formed are called mines, and the men employed in them are denominated miners. If the veins be at a great depth, or, if they extend to any considerable distance beneath the surface of the earth, it becomes necessary, at intervals, to make openings, or shafts, to the surface, in order that fresh air may be admitted and circulated, and that the water, which collects at the bottom, may be carried off by means of drains, pumps, or steam engines, as the situation or circumstances may require or allow. Metalliferous veins (those bearing or yielding metals: from the Latin, metallum, a metal, and fero, I bear) extend irregularly to unknown depths, and they vary in width from an inch to twenty feet. The composition of these veins or lodes (from the Saxon, lædan, to lead) are as valuable as the rocks through which they pass. Lime-stone is the most metalliferous of the secondary rocks, and lead and copper are the metals usually found in it.

As the metals occur in every part of the world, it is evident that their distribution does not, like that of animals and vegetables, depend upon the climate; it is remarkable that those which are the most useful to man are the most abundant, and the most widely-distributed; and it may also be worthy of notice that those portions of the earth which are found to be unfit for the support of animal and vegetable life are generally rich in their mineral treasures.

"These are Thy glorious works, Parent of Good,
Almighty: Thine this universal frame,

Thus wond'rous fair; Thyself how wond'rous then,
Unspeakable! who sitt'st above the heavens,

To us invisible, or dimly seen

In these, Thy lowest works. Yet these declare

Thy goodness beyond thought, and power divine."

I

MILTON.

Before we conclude, however, we must state that notwithstanding the origin and growth of metals in the bowels of the earth form very attractive subjects for examination, nothing satisfactory upon either of them has been attained. Descartes asserts that the metals were created at the same time as the earth; that they were ranged by the laws of gravity, about the centre; and that they were subsequently corroded by acid salts, and carried with them by subterranean heat to various parts of the globe. Although various opinions have been expressed upon these matters, that of Descartes appears to be regarded by many as the best grounded, and most in accordance with the rules of nature. Still, let us not forget the words of the poet Yalden (the intimate friend of Bishop Atterbury), who says:—

"Through dark retreats pursue the winding ore,

Search Nature's depths, and view her boundless store;
The secret cause in tuneful numbers sing,

How Metals first were formed, and whence they spring;
Whether the active sun, with chymic flames,
Through porous earth transmits his genial beams,
With heat impregnating the womb of night,
The offspring shines with its paternal light;
Or whether, urged by subterraneous flames,
The earth ferments, and flows in liquid streams;
Purged from their dross, the nobler parts refine,
Receive new forms, and with fresh beauties shine;
Or whether by creation first they sprung,

When yet unpoised the world's great fabric hung,
Metals the basis of the earth were made,
The bars on which its fixed foundation's laid:

All second causes they disdain to own,

And from the Almighty's flat sprung alone."

GLOSSARY

OF SOME OF THE MOST IMPORTANT TECHNICALITIES
USED IN THE SCIENCE.

N.B.-An explanation of many other terms may be found in the body of the work, upon reference to the index. The following abbreviations are employed in giving the derivations of the various terms:-LAT., for Latin; GK., for Greek; ARAB., for Arabian; and FR., for French.

ABSORB (Lat. absorbeo, I drink in or suck up). To imbibe; to drink in; to suck up, like a sponge.

Potassium is kept under naphtha, on account of the rapidity with which it absorbs, or sucks up, oxygen from the atmosphere.

ACETATE (Lat. acetum, vinegar). A compound of acetic acid with a base.

Acetate of lead is prepared by dissolving litharge in acetic acid.

ACETIC (Lat. acetum, vinegar). Belonging to vinegar. In fact, the name by which acetic acid is more popularly known is vinegar; distilled acetic acid forming distilled or colourless vinegar.

ACID (Lat. aceo, I am sour). A term applied to all bodies which, combining with bases, form salts.

Most of these substances produce that sensation on the tongue which we call sour.

AFFINITY (Lat. affinis, near to, or bordering upon). The tendency or disposition which some substances possess to unite so as to form a new substance.

Calcium is said to possess a great affinity for oxygen, because, as we have already stated, as soon as atmospheric air is admitted to it, it absorbs oxygen, and, burning with an intense white light, is very soon converted into lime, the protoxide of calcium.

AGENT (Lat. ago, I act). When a substance possesses the property of producing chemical action, it is termed a chemical agent.

The mercury may be driven from an amalgam by the agency of heat. Again, aqua regia, a mixture of nitric and hydrochloric acids, is what is generally employed in dissolving gold. Now, in these two examples, heat and aqua regia are said to be chemical agents.

ALCHEMY (Arab. al, the; kimmia, secret; or according to some, Gk. cheo, I pour). The pretended science of converting other metals into gold, &c.

The alchemists endeavoured, and in several instances succeeded, in making short-sighted people believe that they were acquainted with this secret, which they called alchemy.

ALLOY (Lat. ad, to; ligo, I bind). A compound of any two or more metals.

Bell-metal is an alloy; because it consists of copper and tin bound together (i.e., in a state of combination).

We have devoted a separate chapter to alloys.

ALLUVIAL (Lat. alluvies, a muddy stream). Produced by the deposit of mud, &c.; washed down by torrents of

water.

Gold has been found in the alluvial deposits of the Rhone, the Rhine, and the Danube.

AMALGAM (Gk. malaso, I soften). This word has been applied to any combination of mercury with any other metal. Mercury possesses the property of softening (or as mineralogists term it, rendering more malleable) the metals with which it unites.

ANALYSIS (Gk. ana, back; luo, I loosen). This word denotes that series of operations by which the component parts of bodies are determined, whether they be merely separated, or exhibited apart from each other; or whether their distinctive properties be shown by causing them to enter into new combinations.

ANTIDOTE (Gk. anti, against; didomi, I give). Anything which acts as a remedy in counteracting poisons or anything noxious.

If a person has swallowed a powerful acid, chalk will destroy the potency of the acid, if given immediately. The term antidote may therefore be applied to chalk.

ASTRINGENT (Lat. ad, to; stringo, I bind or tie fast). Binding or contracting.

Metallic salts are said to be astringent, when they produce the opposite effect of purgatives.

ATMOSPHERE (Gk. atmos, vapour; sphaira, a globe or The mass of air which surrounds the earth, an animal, or any other body,—such, for instance, as a metal.

ball).

Some metals, without the influence of heat, very readily absorb oxygen from the atmosphere (or that body of vapour which surrounds them), and are converted into oxides.

ATTRACTION (Lat. ad, to; traho, I draw). The tendency of bodies to unite or cohere.

Metals which are readily converted into oxide are said to possess a great attraction for oxygen.

BAROMETER (Gk. baros, weight; metron, a measure). An instrument which measures the weight of the atmosphere, and shows the variation of its pressure, by the rise or fall of a column of mercury in a glass tube attached to a graduated plate.

BASE (Gk. basis, a foundation). This chemical term is generally used to denote the metal, earth, or alkali, which is combined with an acid to form a salt.

BLOW-PIPE. This is an instrument by which a current of air is driven on the flame of a candle, thereby producing an increased heat.

It is of great service in the analysis of minerals, oxides, &c.; and for other chemical purposes.

CALCINE (Lat. calx, lime). To drive off moisture, or any other volatile matter, by the application of heat, from saline, metallic, and other substances, so as to render them friable, as in the operation of lime-burning.

CARBON. This word is applied by chemists to the base of common charcoal, divested of all impurities.