invariable. Some solids are so irregular, that they cannot be compared with any mathematical figure. This is the case with the fragments of a broken rock, chips of wood, fractured glass, &c.

Fluid bodies have no determinate forms, but take their shapes from the vessels in which they happen to be placed. Divisibility.—By the divisibility of matter, we mean that a body may be divided into parts, and that these parts may again be divided into other parts.

It is quite obvious, that if we break a piece of marble into two parts, these two parts may again be divided, and that the process of division may be continued until these parts are so small as not individually to be seen or felt. But as every body, however small, must possess extension and form, so we can conceive of none so minute but that it may again be divided. There is, however, possibly, a limit, beyond which bodies cannot be actually divided, for there may be reason to believe that the atoms of matter are indivisible by any means in our power. But under what circumstances this takes place, or whether it is in the power of man during his whole life, to pulverize any substance so finely, that it may not again be broken, is unknown.

We can conceive, in some degree, how minute must be the particles of matter, from circumstances that every day come within our knowledge.

A single grain of musk will scent a room for years, and still lose no appreciable part of its weight. Here, the particles of musk must be floating in the air of every part of the room, otherwise they could not be every where perceived.

Gold is hammered so thin, as to take 282,000 leaves to make an inch in thickness. Here, the particles still adhere to each other, notwithstanding the great surface which they cover,-a single grain being sufficient to extend over a surface of fifty square inches.

The ultimate particles of matter, however widely they may be diffused, are not individually destroyed, or lost, but under certain circumstances, may again be collected into a body

What bodies are irregular? What is meant by divisibility of matter? Is there any limit to the divisibility of matter? Are the atoms of matter divisible? What examples are given of the divisibility of matter? How many leaves of gold does it take to make an inch in thickness? How many square inches may a grain of gold be made to cover?

without change of form. Mercury, water, and many other substances, may be converted into vapor, or distilled in close vessels, without any of their particles being lost. In such cases, there is no decomposition of the substances, but only a change of form by the heat, and hence the mercury and wa ter assume their original state again on cooling.

When bodies suffer decomposition or decay, their elementary particles, in like manner, are neither destroyed nor lost, but only enter into new arrangements, or combinations with other bodies.

When a piece of wood is heated in a close vessel, such as a retort, we obtain water, an acid, several kinds of gas, and there remains a black, porous substance, called charcoal. The wood is thus decomposed, or destroyed, and its particles take a new arrangement, and assume new forms, but that nothing is lost is proved by the fact, that if the water, acid, gases, and charcoal be collected and weighed, they will be found exactly as heavy as the wood was, before distillation.

Bones, flesh, or any animal substance, may in the same manner be made to assume new forms, without losing a particle of the matter which they originally contained.

The decay of animal or vegetable bodies in the open air, or in the ground, is only a process by which the particles of which they were composed, change their places, and assume new forms.

The decay and decomposition of animals and vegetables on the surface of the Ear.h form the soil, which nourishes the growth of plants and other vegetables; and these, in their turn, form the nutriment of animals. Thus is there a perpetual change from death to life, and from life to death, and as constant a succession in the forms and places, which the particles of matter assume. Nothing is lost, and not a particle of matter is struck out of existence. The same matter of which every living animal, and every vegetable was formed, before and since the flood, is still in existence. As nothing is lost or annihilated, so it is probable that nothing has been added, and that we, ourselves, are composed of particles of

Under what circumstances may the particles of matter again be collected in their original form? When bodies suffer decay, are their particles lost? What becomes of the particles of bodies which decay? Is it probable tha any matter has been annihilated or added, since the first creation?

matter as old as the creation. In time, we must, in our turn, suffer decomposition, as all forms have done before us, and thus resign the matter of which we are composed, to form new existences.

Inertia. Inertia means passiveness or want of power. Thus matter is, of itself, equally incapable of putting itself in motion, or of bringing itself to rest when in motion.

It is plain that a rock on the surface of the earth, never changes its position in respect to other things on the earth. It has of itself no power to move, and would, therefore, for ever lie still, unless moved by some external force. This fact is proved by the experience of every person, for we see the same objects lying in the same positions all our lives. Now, it is just as true, that inert matter has no power to bring itself to rest, when once put in motion, as it is, that it cannot put itself in motion, when at rest, for having no life, it is perfectly passive, both to motion and rest, and therefore either state depends entirely upon circumstances.

Common experience proving that matter does not put itself in motion, we might be led to believe, that rest is the natural state of all inert bodies, but a few considerations will show, that motion is as much the natural state of matter as rest, and that either state depends on the resistance, or impulse, of external causes.

If a cannon ball be rolled upon the ground, it will soon cease to move, because the ground is rough, and presents impediments to its motion; but if it be rolled on the ice, its motion will continue much longer, because there are fewer impediments, and consequently, the same force of impulse will carry it much farther. We see from this, that with the same impulse, the distance to which the ball will move must depend on the impediments it meets with, or the resistance it has to overcome. But suppose that the ball and ice were both so smooth as to remove as much as possible the resistance caused by friction, then it is obvious that the ball would continue to move longer, and go to a greater distance. Next suppose we avoid the friction of the ice, and throw the ball through the air, it would then continue in motion still longer with the same

What is said of the particles of matter of which we are made? What loes inertia mean? Is rest or motion the natural state of matter? Why does the ball roll farther on the ice than on the ground? What does this prove?

force of projection, because the air alone, presents less impediment than the air and ice, and there is now nothing to oppose its constant motion, except the resistance of the air, and its own weight, or gravity.

If the air be exhausted, or pumped out of a vessel by means of an air pump, and a common top, with a small, hard point, be set in motion in it, the top will continue to spin for hours, because the air does not resist its motion. A pendulum, set in motion, in an exhausted vessel, will continue to swing, without the help of clock work, for a whole day, because there is nothing to resist its perpetual motion, but the small friction at the point where it is suspended.

We see, then, that it is the resistance of the air, of friction, and of gravity, which cause bodies once in motion to cease moving, or come to rest, and that dead matter of itself, is equally incapable of causing its own motion, or its own

rest.

We have perpetual examples of the truth of this doctrine, in the moon, and other planets. These vast bodies move through spaces which are void of the obstacles of air and friction, and their motions are the same that they were thousands of years ago, or at the beginning of creation.

Attraction. By attraction is meant that property, or quality in the particles of bodies, which make them tend toward each other.

We know that substances are composed of small atoms, or particles, of matter, and that it is a collection of these, united together, that forms all the objects with which we are acquainted. Now, when we come to divide, or separate any substance into parts, we do not find that its particles have been united, or kept together by glue, little nails, or any such mechanical means, but that they cling together by some power, not obvious to our senses. This power we call attraction, but of its nature or cause, we are entirely ignorant. Experiment and observation, however, demonstrate, that this power pervades all material things, and that under different modifications, it

Why, with the same force of projection, will a ball move farther through the air than on the ice? Why will a top spin, or a pendulum swing longer, in an exhausted vessel than in the air? What are the causes which resist the perpetual motion of bodies? Where have we an example of continued motion, without the existence of air and friction? What is meant by attraction? What is known about the cause of attraction? Is attraction common to all kinds of matter, or not?

not only makes the particles of bodies adhere to each other, but is the cause which keeps the planets in their orbits as they pass through the heavens.

Attraction has received different names, according to the circumstances under which it acts.

The force which keeps the particles of matter together, to form bodies, or masses, is called attraction of cohesion. That which inclines different masses towards each other, is called attraction of gravitation. That which causes liquids to rise in tubes, is called capillary attraction. That which forces the particles of substances of different kinds to unite, is known under the name of chemical attraction. That which causes the needle to point constantly towards the poles of the earth is magnetic attraction; and that which is excited by friction in certain substances, is known by the name of electrical attraction.

The following illustrations, it is hoped, will make each kind of attraction distinct and obvious to the mind of the student. Attraction of cohesion acts only at insensible distances, as when the particles of bodies apparently touch each other.

Take two pieces of lead, of a round form, an inch in diameter, and two inches long; flatten one end of each, and make through it an eye-hole for a string. Make the other ends of each as smooth as possible, by cutting them with a sharp knife. If now the smooth surfaces be brought together, with a slight turning pressure, they will adhere with such force that two men can hardly pull them apart by the two strings.

In like manner, two pieces of plate glass, when their surfaces are cleaned from dust, and they are pressed together, will adhere with considerable force. Other smooth substances present the same phenomena.

This kind of attraction is much stronger in some bodies han in others. Thus, it is stronger in the metals than in most other substances, and in some of the metals it is stronger than in others. In general, it is most powerful among the particles of solid bodies, weaker among those of liquids, and

What effect does this power have upon the planets? Why has attraction received different names? How many kinds of attraction are there? How does the attraction of cohesion operate? What is meant by attraction of gravitation? What by capillary attraction? What by chemical attraotion? What is that which makes the needle point towards the pole? How is electrical attraction excited? Give an example of cohesive attraction.