stance, for the discovery of which we are indebted to our celebrated countryman Davy. It is named BoRACIUM, and was obtained by an ingenious process from the acid of borax, yielded by the borax of commerce, which is a borate of soda, a combination of boracic acid with a large proportion of soda. Boracium is an opake, brittle substance, of a dark olive colour. It burns when slightly heated, and with considerable brilliancy, especially in oxygen or chlorine.

From the water of the ocean, sea salt may be ob tained, which yields peculiar products. If sea salt is mixed with black oxide of manganese, and distillation employed, a gas is obtained of very important properties. It is of a yellowish green colour, and incapable of being respired. It will, however, support combustion, and even produce it in phosphorus, antimony, &c. It destroys vegetable colours, and is therefore highly useful for bleaching. It was considered as being a compound of muriatic acid and oxygen, and was named oxymuriatic acid; but Sir H. Davy ascertained that it does not contain any oxygen, and, concluding it to be a peculiar simple substance, named it, from its colour, CHLORINE.

Chlorine combines with oxygen, thus becoming a gas of a yellow colour, and manifesting properties very different from those of chlorine. It is named by its discoverer, Davy, EUCHLORINE. It is obtained by the action of chlorine, in a liquid form, on a salt termed hyper-oxy-muriate of potash. When heated

it decomposes, light and heat being produced. It is composed of two parts, in volume, of chloric gas and one of oxygen.

Chlorine combines readily also with hydrogen, and thus forms the substance named MURIATIC ACID. It is formed by about one part of hydrogen to thirty-five of chlorine. In a gaseous form it is colourless, has a pungent and peculiar smell; it cannot be respired, nor will it support combustion. It mixes eagerly with water, forming liquid muriatic acid. The salts formed by this acid, combining with different bases, are called muriates.

Chlorine combines with many other bodies, forming substances of peculiar properties. These substances are designated as containing chlorine by the termination ane. Thus we have phosphorane, sulphurane, &c.

Equal parts of chlorine gas and carbonic oxide gas being exposed to a strong light, they combine, and a gas is formed of just half the bulk of the two gases. This peculiar gas was named by its discoverer, Dr. John Davy, PHOSGEN GAS, from its being formed by the action of light.

FLUORIC ACID, possessing very uncommon properties, is obtained from the mineral kingdom only. It is yielded from that combination of it with lime, which is termed fluor spar, and exists in large quantities in Derbyshire. Sulphuric acid being poured on this substance, fluoric acid gas is yielded. It is colourless, it cannot be respired, nor will it support

combustion. It fumes on being exposed to the air, and greedily absorbs water. But its most curious property is that of dissolving glass with extraordinary rapidity; and hence it is employed for etching on glass. On fluoric acid gas being distilled in glass vessels, it dissolves the flint, which is retained in the gas, deposited on the surface, when it comes in contact with water.

The important discoveries of our illustrious countryman, Davy, have occasioned some difficulties as to the arrangement which should be adopted for the substances of which we have next to treat. These, until his discoveries, were considered as simple substances, earths and alkalies; but by his experiments the greater part of these substances have been found to be compounds, of which new and hitherto unknown metals were the bases. But, as it will be more instructive and more interesting, we shall consider these bodies under their former designations, and in the same order in which they have hitherto been disposed; especially since, by so doing, we shall have the opportunity of noticing the remarkable discoveries to which we have alluded.

ALKALIES.-1. AMMONIA, or volatile alkali, formed, in a gaseous state, of three parts in bulk of hydrogen gas and one part of azote, is acrid and pungent to the smell and taste. It cannot be breathed, nor will it allow combustion in it. It may be obtained in a solid or a fluid form, when it is known as ammonia, or as liquid ammonia, commonly called spirits of hartshorn. Mixed with oxygen and exposed

to the electric spark, a combustion and decomposition ensue. If chlorine be employed instead of oxygen, it burns with considerable splendour.

It appears from a curious experiment that the basis of ammonia is a metal; and this assumed metal has been named AMMONIUM. Ammonia appears to be a combination of this metal with oxygen.

2. POTASH, or vegetable fixed alkali, is yielded by the ashes of vegetables that grow inland. It is very aerid and corrosive, acts on the skin, and changes vegetable blues green. Mixed with phosphorus and distilled, phosphuretted hydrogen gas is yielded, possessing the property of taking fire on coming in contact with the air. Aided by the galvanic battery, Davy demonstrated the metallic base of potash. It is a white, soft, malleable metal, which forms alloys with the other metals. It is lighter than water, or, indeed, than any known liquid. Sp. grav. 0,885. It rapidly seizes on oxygen, and then becomes potash, which appears to be composed of 86 parts of the metal and 14 of oxygen. The metal is named

POTASSIUM.

3. SODA, or mineral fixed alkali, is found ready formed in the earth, and is obtained from the ashes of marine plants. It agrees with potash in most of its properties. Like potash, our countryman found it to be formed of a peculiar metal in combination with oxygen. This metal he found to be white and solid, but very malleable, and so soft as to weld, merely by pressure. It is lighter than water. Sp. gr. 0,9348. Soda appears to be formed by 78 parts

of the metal and 22 of oxygen; its affinity with which appears to be similar to that of potassium. This metal is named SODIUM.

The EARTHS are nine in number, four of which, lime, magnesia, barytes, and strontian, are of an alkaline nature: the other five neither neutralize acids, nor produce any change on vegetable blues.

1. ALUMINE, is white, and when pure has neither taste nor smell. It exists in a great proportion in clay, to which it gives ductility. With sulphuric acid it forms sulphate of alumine, or the alum of commerce, from which it may be obtained in a pure state by precipitation. Although its metallic base has not yet been demonstrated, its existence is highly probable.-2. YTTRIA is found in a Swedish mineral, named gadolinite. It is obtained from this substance in a white powder, having neither taste nor smell. It is also supposed to be a metallic oxide.-3. GLUCINA is found in the beryl and the emerald. It is also a soft white powder, without taste or smell. It is also presumed to have a metallic base.-4. ZIRCONIA is found in the mineral called zircon, and in the hyacinth. It is a white powder, with a harsh feel. It is supposed to be a metallic peroxide.-5. SILICA chiefly contributes to the formation of siliceous minerals, as quartz, rock-crystal, flint, &c. It is obtained in a white powder without taste or smell, and of a very harsh feel; it also is supposed to have a metallic base.-6. LIME is the chief constituent of marble, chalk, limestone, &c. It