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bines with aluminum, forming alumina, which is the basis of alum, of fullers' earth, and of clays; or with silicum, forming silica, the basis of Aint, in quartz. Pottery consists chiefly of these two earths,

Some are called alkalies, or alkaline earths: thus lime, an alkaline earth, is formed from oxygen and calcium ; and potassa from oxygen and potassium. This latter alkali-potassa, with silica forms glass.

Oxides and acids, besides their other peculiarities, differ in this, that the former are produced with less oxygen than the latter. · Acids are compounds of bodies with oxygen, which possess peculiar properties, such as a sour taste. The stronger are corrosive. Acids change vegetable purples to red; instances are common, as vitriol, aquafortis, vinegar, and fluoric acid, with which etching on glass is done. Arsenious acid, a compound of the metal arsenic with oxygen, is that virulent poison the white arsenic of the shops.

Alkalies are also for the most part compounds of oxygen with different substances. They have an acrid taste; they change vegetable purples for the most part to green; with acids they form that great class of compounds, the salts ; with oily or fatty substances they form soaps, hard soap being formed from the soda, soft soap from the potash.

Carbon also is a simple substance, and forms compounds with other bodies called carburets ; carburetted hydrogen, or common burning gas, is one ; steel is a carburet of iron. Black lead, as it is called, is another carburet of iron.

Sulphur combines freely with other bodies, and when the combinations are not acid, they are called sulphurets. Sulphurous acid gas is very abundant near volcanoes ; and pyrites, that is, sulphur in combination with iron, called also the sulphuret of iron, is one of the chief component parts in volcanic eruptions.

1. Vide Root. 2. Oxygen, chlorine, &c. are gases which will enable such bodies as sulphur, carbon, and the metals to burn in them, but will not themselves

burn: the former are called supporters of combustion, the latter combustible bodies.

ASSYRIA.

To the Death of Semiramis. W en the rest of mankind were scattered into different parts of the earth, there were a number of people who remained near the tower of Babel. They continued to inhabit the land of Shinar, which was a warm country, and very fertile. In course of time they extended over a much larger tract of country, and built towns and cities.

This region received the name of Assyria. It was the first of the nations of the earth. Its boundaries varied at different times, but its place on the map may be seen in the vicinity of the two rivers Tigris and Euphrates, northward of the Persian Gulf.

Asshur, the grandson of Noah, was the first ruler of Assyria. In the year 2229 B. C. he built the city of

Nineveh, and surrounded it with walls a hundred feet high.

But the city of 3 Babylon, which was built a short time afterwards, was superior to Nineveh both in size and beauty. In this city there were magnificent gardens, belonging to the royal palace. They were constructed in such a manner that they appeared to be hanging in the air without resting on the earth.

The city of Babylon was first built by Nimrod, that mighty hunter of whom the Bible tells us. But the person who made all the beautiful gardens and palaces, was a woman named Semiramis.

She had been the wife of Ninus, king of Assyria ; but when king Ninus died, queen Semiramis became sole ruler of the empire. She was tormented with a wicked desire to conquer all the nations of the earth. So she collected an immense army, and marched against the powerful

1. Vide Root.

2. On the Tigris.

3. On the Euphrates,

king of the Indies, who lived in what we now call Hindostan , a country lying to the south-east of Assyria.

When the king of the Indies, who was very rich and powerful, heard that queen Semiramis was coming to invade his dominions, he mustered a vast number of men to defend them. Besides his soldiers he had a great many elephants.

Now queen Semiramis had no elephants, and being afraid that the king of the Indies would overcome her, she endeavoured to prevent this misfortune by a very curious contrivance. In the first place, she ordered three thousand brown oxen to be killed.

The hides of the dead oxen were stripped off, and sewed together in the shape of elephants. These were placed upon camels, and when the camels were drawn up in battle array, they looked pretty much like a troop of great brown elephants. Doubtless the king of the Indies wondered where queen Semiramis had caught them.

This silly device was, however, of no avail. The Assyrian army was routed, and the king of the Indies gained a complete victory. Queen Semiramis was sorely wounded; but she got into a chariot, and drove away at full speed from the battle field. She finally escaped to her own kingdom, but in a very sad condition.

She then took up her residence in the palace at Babylon. But she did not long enjoy herself there. It is said that her own son, whose name was Ninias, put his mother to death, that he might get possession of the throne, and reign over the people.

GEOGRAPHICAL.-Assyria at its greatest extent comprised Assyria Proper, Modia,

Babylonia or Chaldea, Syria, Egypt, and part of Lybia and Ethiopia. What

were the capitals of those countries? What principal rivers were included in this empire ? and into what seas did they

run? What degrees of latitude and longitude bounded Assyria, at the time of its greatest

extent? CHRONOLOGICAL.-Semiramis, 1974 B.C.

CHEMISTRY.

Alloys and Salts. Alloys are combinations of metals one with another, and are of great importance in commerce and the arts.

All alloys of mercury are called ' amalgams; the surface of a shilling put into quicksilver, will be amalgamated quickly; looking-glasses are silvered with an amalgam of tin. From the readiness with which mercury attracts gold, it is used in separating that metal from its ores, the separation of the gold from the mercury being an easy process.

As the result of alloying, sometimes the compound will be harder, as in coin when a little copper is mixed with the gold. The gold coin of the Dutch and Athenians, which was unalloyed, was very soft.

The "fusibility of the compounds is in some increased ; thus platinum is rendered fusible by arsenic: lead, tin, and bismuth, when mixed together, melt in boiling water. Solders are easily fusible compounds of metals, by which others are made to join ; silver, brass, and a little zinc form a solder for silver. Tin and lead is a common solder.

The colour is altered in some,-as arsenic, a steel colour, and copper, a red, joined together are nearly as white as silver. The resulting compound is sometimes more volutile, as when gold is mixed with mercury. There are other useful results which cannot here be mentioned. ..

The most commonly known alloys are brass, which is composed of copper and zinc; and bell-metal, which is composed of copper and tin. Pewter, when pure, is composed of tin, and a little antimony, copper, and bismuth ; when impure, it has some lead in addition. Bronze chiefly consists of copper with a little tin, and sometimes zinc.

2 Salts are compounds of acids, with 3 bases which are generally oxides of some kind or other.

When an acid joins a base so that the properties peculiar to each are no longer evident, it is called neutral.

Sulphuric acid is very sour; soda is very acrid ; sulphate of suda, which is the union of both, is neither. Magnesia is earthy; combined with the same acid it forms sulphate of magnesia or Epsom salts. Aquafortis is sour and acrid; potassa is acrid--together they form saltpetre.

When there is more acid than base, an acid taste is still left, as alum, which is sulphuric acid and alumina. The deposit in wine casks, (cream of tartar) a salt of this kind, is tartaric acid and potassa ; these are called

super-salts; there are also'sub-salts, that is, with less acid than base.

One acid may combine with two bases, as in tartar emetic, out of which antimony wine is made ; the acid is tartaric acid, the bases antimony and potassa. With acids, the oxides of metals form salts.

The gallic acid (acid of gall-nuts) and oxide of iron, form ink, and is the basis of black dyes. Vinegar or acetic acid with oxide of copper is verdigris. Sulphuric acid with oxide of copper is blue stone.

Salts have generally peculiar crystalline forms, as cubic, prismatic, Aat in plates, long, or in needles, &c, The determining the forms peculiar to salts and other bodies that crystallize is called crystallography.

The salts of tin are much used as mordants in dyeing. The salt which gives bone its firmness is the phospha:e of lime, and this by soaking in acid may be all taken out, and leave only the animal part, which will then have exactly the shape of bone, but it will be flexible.

1. Vide Root. 2. Out of this class chemistry produces many valuable medicines. 3. A base is any substance with which an acid combines to form a salt.

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