colouring matter of all soils, and is contained in all plants and animals, and is essential to their existence.

Jet.-A kind of wood coal which receives a fine polish, found in detached pieces in the aluminous strata of Whitby, and occurs in other marshy and soft strata.

Lava. The mineral molten matter poured from the craters and sides of volcanoes.

Lime. The caustic principle, produced by the calcination of limestone or carbonate of lime. Magnesia. A caustic alkaline earth.

Manganese.-Oxide of manganese, occurs both compact and crystalized.

Marl. A mineral abounding in the new secondary formation, and consisting principally of various proportions of clay and carbonate of lime.

Mercury. This remarkable metal is sometimes found native in small quantities in primitive rocks, but more commonly in some coal formations of foreign countries.

Mollusca or Molluscous Animals. Such animals as have soft bodies and no bones. All shell-fish are so called, from mollis, soft.

Naptha. A mineral inflammable fluid, of which there are many springs; most probably a production of coal. Nitrates. Salts produced by the union of nitric acid with bases, of which the nitrate of lime, nitrate of potash (nitre) and nitrate of soda are common instances.

Nitre.-Nitrate of Potash.-This well known salt is found native in many parts of the world. It is also made. artificial by the mixture of animal and vegetable substances with old plaster, or other calcareous matter, by the fermentation of which nitrates are produced.

Nitrogen. The indifferent, or deluting principle of the atmosphere, commonly called azote. Also one of the elements of most vegetable and animal substances, but chiefly abounding in the latter. With oxygen, nitrogen forms nitrous oxide and nitric acid; with hydrogen,

ammonia.

Oolite or Roe-stone.-So called from the resemblance of its molecules to the roe of fish. These rocks all abound in organic remains.

Organic Remains. The remains of animals and plants found in a fossil state.

Oxides. Substances produced by the chemical union of oxygen with other elements or their compounds. Rust of iron and red lead are familiar instances of oxides of metals.

Oxygen. The most abundant and important element in nature; as in a solid state it constitutes about one-half of the rocks which form the crust of the earth; and in a gaseous form, about one-fifth of the atmosphere; in the latter state it is the active agent for the support of animal life, and of the combustion, as well as the decomposition by decay of vegetable and animal substances. Phosphates.-Salts formed by the union of phosphoric acid with bases. Phosphate of lime is essential to the growth of plants and the formation of their seeds.

Phosphorus.-This is a highly inflammable substance. Phosphorus in the shape of phosphate of lime is extensively diffused, as it exists in almost all mineral waters, but is seldom found in any considerable masses. It is con

tained in all animal substances.

Potash. It is a constant ingredient of the mineral called felspar, of which it generally forms about 14 per cent. ; it therefore constitutes a part of many of the older rocks, but more particularly of granite. It is a necessary ingredient of all fertile soils, and is found in the ashes of almost all plants.

Reddle, or Red Chalk.-A red ponderous earthy mineral, containing much peroxide of iron, much used for marking sheep, and as an ingredient in coarse paints.

Salt, Common.-Chloride of Sodium. This well-known substance is found in vast masses in many parts of the world, sometimes composing entire mountains, and in some instances at great elevations above the sea. The salt of England is supplied from the thick beds of rocksalt in Cheshire, and the brine springs of Droitwich. Sedimentary Rocks -Those strata which have been mechani

cally deposited by water. All the stratified rocks are called sedimentary.

Silex.-The earth of flints, the chief component of most sand. Silicates. Substances formed by the combination of silica with

alkaline and earthy bases, in which silica plays the part of an acid. Thus we have silicate of soda or potash (glass) silicate of alumina, lime, magnesia, iron, &c. Silicious.-Flinty or composed of flinty particles. Soda. This alkali is also like Potash an ingredient of some of the igneous and older rocks and forms from 10 to 14 per cent of that called compact felspar, and is also found in many other mineral substances. It is an essential ingredient in all fertile soils, and is always found in the ashes of plants.

Sulphur. This combustible mineral occurs massive, dessemi

nated and crystalized; often investing and penetrating other minerals; and in veins and beds in primitive rocks, in many parts of the world. The source from which Europe is principally supplied is a sunken plain near Naples, called the Solfatara, from whence it has been raised upwards of 2000 years. Many volcanoes yield it in great abundance. Veins.-Fissures or cracks in rocks, generally filled up by materials differing from the rock, and often containing the ores of metals; these are sometimes several yards wide, and others branch into very narrow divisions, resembling the veins of an animal, whence their name.