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it must, when it comes to be better understood, find friends and favourers either in this country or some other, with abilities to defend what shall have been rightly done in this great subject, and to improve it by their own more successful labours.

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DISCOURSE I.

Of Matter, and the several Kinds of

MATT

Bodies.

ATTER is that tangible substance which occupies space, and is subject to a variety of visible forms. It is either homogeneous or heterogeneous; that is, either simple or compound. There are, indeed, very few masses of matter that are perfectly simple. Many seem so, as the water of the sea, and the mould of the earth; but seawater has a considerable mixture of salt in it, with other earthy and bituminous parts, which soon ferment when the sea-water is stagnant, and send forth a fætid smell. The mould of the earth, how uniform soever it may appear by its colour, is made up of earth, oil, salt, watry, and metallic parts. Water may be rendered simple by distillation, and earth by burning; but absolute simplicity seems rarely to be found, except it be in the matter of light or fire.

The

The first particles or principles of which matter is composed are atoms, those very small invisible elements of bodies which cannot be cut or divided, for such is the signification of the word atom. It has been a question, whether matter can be infinitely divided; that is, whether the parts of any given mass can be multiplied without end. The notion of an atom is against this; but sometimes we mean no more by an atom than those small particles, the figures of which are proper to the bodies composed by them, and which can never be changed so long as that body preserves its nature. Bodies may be very much changed in their form and outward appearance, while their component parts suffer no change. What can differ more from itself than the metal of lead, in its solid state, from the powder of red lead? Yet this powder will easily revert to its former condition of solid lead, when mixed over the fire with any oily or inflammable matter, which the chemists call phlogiston. Even the glass of lead, when ground with charcoal, and melted in the fire, will return again to its metallic form.

Matter is capable of many seeming transformations, but no real transmutations have

ever been discovered. Plants and animals are not transmuted from the matter of the earth by which they are nourished; because the matter proper for the nourishment of any particular vegetable will be exhausted by degrees from the soil, which could not happen if bodies received their growth from the transmutation of particles originally homogeneous. At their dissolution, both plants and animals return to the same sort of vegetable earth out of which they arose. An artificial analysis of their composition, as well as their own natural decay, shews them to be made up of such ingredients as the earth itself is, the particular nature of which belongs to another subject.

Constituent Parts of Bodies.

Atoms, understood in a grosser sense, as constituent parts of bodies, are distinguished by their figures; some of which are cubic, some in angular columns, some round, some acute or spiculated: the small grains of sea salt and of lead are cubic, nitre is hexangular, blood and oil are globular, corrosive sublimate spiculated, and antimony is in small filaments like needles. Where the discernible

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