A Catechism of Familiar Things Part 29

A white metal, softer than any other excepting lead, more elastic, and more sonorous. Though tin is the lightest of all metals, its ore is, when rich, the heaviest of all metallic ores. It has both smell and taste; is less ductile than some harder metals, though it may be beaten into very thin leaves; and it fuses so quickly, that it requires a heat much less than is sufficient to make it red-hot.

Was not the use of Tin very early known?

Tin was found in Britain from the earliest ages; the Phenicians traded to Cornwall for this metal 600 years before Christ.

Where are the princ.i.p.al Tin Mines?

In Saxony, Cornwall, and Bohemia. Tin is also found in Spain, Sumatra, Siam, Mexico, and Chili. A few specimens have been found at Goshen, in Ma.s.sachusetts.

_Specimens_, samples.

In what state is Tin generally found?

Tin is sometimes found native or pure, but most frequently alloyed with other metals: the working of tin mines is attended with much difficulty, on account of their great depth, and the hard rocks which obstruct the progress of the miners, who are often obliged to cut through them. This metal is very useful in the making of domestic utensils, for coating the inside of copper and iron vessels, and for various other purposes.

_Obstruct_, to stand in the way.

What is Lead?

A coa.r.s.e, heavy metal, of a bluish grey color: it is so soft and flexible, that it is easily cut with a knife, and rolled out into sheets, &c.; it is very fusible and inelastic, but less ductile and sonorous, than any other metal. Next to gold, platina, and mercury, it is the heaviest of the metals, being eleven times heavier than an equal bulk of water. This metal loses its malleability in proportion as it is heated: as soon as it melts it calcines, and greyish-colored ashes are formed on its surface; when returning from a fluid to a solid state, it is easily divided into small grains or powder, or formed into shot, &c. Lead was in common use among the ancients.

_Flexible_, yielding, easily bent.

_Sonorous_, giving sound when struck.

Where is Lead found?

In various countries; but it abounds princ.i.p.ally in Great Britain and Spain; the lead mines of Illinois, Wisconsin, and Iowa, are among the richest in the world. Lead is a metal of great utility; it easily melts and mixes with gold, silver, and copper; hence it is employed in refining gold and silver, as it separates all the dirt and impurities from them; it is much used in building, particularly for covering gutters, pipes, &c.; lead is also used in varnishes and oil-painting, and makes the basis of the glazing of all the earthen and pottery wares.

_Refining_, cleansing, purifying.

_Varnishes_, preparations for beautifying and preserving various articles.

What is peculiar to the ore of Lead?

The ore of this metal is so poisonous, that the steam arising from the furnaces in which it is smelted infects the gra.s.s of all the neighboring places, and kills the animals which feed on it: culinary vessels lined with a mixture of tin and lead, are apt to convey pernicious qualities to the food prepared in them. There are various preparations of lead, serving for different purposes.

_Infects_, corrupts.

_Culinary_, adapted to the purposes of cooking.

_Pernicious_, hurtful, dangerous.

_Ore_, the mineral soil, earth, or stone dug out of the mines, which contains the metal.

What is Black Lead?

It is a kind of mineral, of a deep s.h.i.+ning black or bluish color, soft and unctuous to the touch; it is insoluble in acids, and infusible by fire. Black lead has been found in many parts of the world, in a state of greater or less purity, but it is the English black lead which is the most esteemed.

_Insoluble_, incapable of dissolving.

_Infusible_, not capable of being melted.

Is Black Lead a proper term for this mineral?

No; because, in reality, there is not a particle of lead in it. On the spot where it is procured, it is called by two or three different names, but the most usual is Plumbago.

Where is the best Black Lead found?

The best and greatest quant.i.ty is found in England, in a mine near Keswick, in c.u.mberland. It is much used for pencils or crayons, for writing, drawing, &c.; for this purpose it is sawn into slips, and fitted into a groove in a strip of soft wood, as cedar, &c., over which another is placed and fastened with glue.

What is Platina?

A metallic substance, more recently discovered than the metals already described; and a.n.a.logous to the perfect metals, especially gold,--many of whose properties it possesses.

_a.n.a.logous_, bearing a resemblance.

Whence is its name derived?

It is the diminutive of _plata_, silver, to which it appears very similar; platina being a silver-colored metal, in small grains.

_Diminutive_, a word lessening the meaning of the original.

Whence is it obtained?

Mostly from Russia, and, also from South America. Its color does not tarnish by exposure to the air, and appears to be equally permanent with that of pure gold; the metal is indestructible by fire. Platina is capable of being alloyed with all metals; is fused with difficulty, but by great labor may be rendered malleable: it is also the heaviest metal, being 21 times heavier than water.

_Permanent_, lasting.

Are there any other Metals besides those already mentioned?

In addition to the metals known and used by the ancients, the chemical science of later ages has, by decomposing other earths, added more than thirty to the number of metals, some of them more curious than useful; several of these are lighter than water. All the metals possess different and distinct properties from each other. They are divided into two cla.s.ses, the malleable and the brittle metals. These last may be again divided into two others,--namely, those which are easily, and those which are with difficulty fused.

What do you mean by Metallurgy?