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the gold will be equally diffused throughout the whole mass of silver; so that if one grain of the mass be dissolved in a liquid called aqua fortis, which is crude nitric acid, the gold will fall to the bottom. By this experiment it is evident that a grain may be divided into 5761 visible parts, for only the 5761st part of the gold is contained in a single grain of the mass.

Gold-beaters can spread a grain of gold into a leaf containing fifty square inches; and this leaf may be readily divided into 500,000 parts; each of which is visible to the naked eye. By the help of a microscope, which magnifies the area or surface of a body 100 times, the 100th part of each of these becomes visible; that is, the fifty millionth part of a grain of gold will be visible, or a single grain of that metal may be divided into fifty million visible parts. But the gold which covers the silver wire, used in making what is called gold lace, is spread over a much larger surface; yet it preserves, even if examined by a microscope, a uniform appearance. It has been calculated that one grain of gold, under these circumstances, would cover a surface of nearly thirty square yards.

In the gilding of buttons, five grains of gold, which is applied as an amalgam with mercury, is allowed to each gross, so that the coating deposited must amount to the 110,000th part of an inch in thickness.

The natural divisions of matter are still more surprising. In odoriferous bodies, such as lavender-water, camphor, musk, asafoetida, and scents of various kinds, a wonderful subtilty of parts is perceived: for though they are perpetually filling a considerable space with odoriferous particles, yet these bodies lose but a very small part of their weight or quantity in a great length of time. One grain of musk bas been known to perfume a room for the space of twenty years. In the perfume emanating from a flower, how diminutive must be the particles that reach the olfactory nerves of the nose when we smell them, and which are themselves invisible and cause no sensible diminution to the bulk of the plant.

The Lycoperdon, or puff-ball, is a fungus growing in the form of a tubercle, which, being pressed, bursts, emitting a dust so fine and so light, that it floats through the air with the appearance of smoke. Examined under the microscope, this dust, which is the seed of the plant, appears under the

form of globules of an orange colour, perfectly rounded, and in diameter about the fiftieth part of a hair; so that if this calculation be correct, and a globule were taken having the diameter of a hair, it would be one hundred and twenty-five thousand times as great as the seed of the lycoperdon.

In Leslie's "Natural Philosophy" we read that millions of the insect Monas gelatinosa, found among duck-weed, are sporting about in one drop of liquid: and that the Vibrio undula, found on the same plant, is computed to be ten thousand million times smaller than a hemp seed. Now, if it be admitted that these little animals are possessed of organized parts, such as a heart, stomach, muscles, veins, arteries, &c., and that they are possessed of a complete system of circulating fluids, similar to what is found in larger animals, we seem to approach to an idea of the infinite divisibility of matter. It has indeed been calculated that a particle of the blood of one of these animalcules is as much smaller than a globe onetenth of an inch in diameter, as that globe is smaller than the whole earth. Nevertheless, if these particles be compared with the particles of light, it is probable that they would be found to exceed them in bulk as much as mountains exceed single grains of sand.

There is a very familiar example in the sweetening of tea, a small lump of sugar extending its influence throughout the entire cup-full; and in one drop how diminutive must be the portion of sugar.

Again, a drop of port-wine put into a tumbler of water will tinge the whole mass, so that one drop of it can contain but a very minute portion of the wine.

A single grain of copper dissolved in nitric acid, will give a blue tint to three pints of water: by which the copper is attenuated at least one hundred million times.

I might enumerate many other instances of the same kind; but these, I doubt not, will be sufficient to convince you into what very minute parts matter is capable of being divided; and with these we will close our present conversation.

Fa. Now, my dear Charles, let me be the questioner, after our several conversations relating to the same subject, in order to find if you have entered into the spirit of the information you have received, and made such deductions as may be useful to you.

Ch. Most willingly, Papa.

Fa. You have learned, in this latter conversation, that matter is philosophically defined to be an extended, impenetrable, inactive, and moveable substance. How do you understand these terms?

Ch. Extension is that principle of matter by which it occupies a part of space. Impenetrability implies a property by which two bodies cannot exist in the same place at the same time. Inactive and moveable apply to a body which resists, in any degree, a force impelling it to a change of state, with regard to motion and rest; but which may be moved, if sufficient force be applied to it.

Em. Of what shape are the ultimate particles of the generality of natural solids?

Fa. It is the opinion of most philosophers I have read that they are, for the most part, spherical; but many different ideas have been formed as to the nature of matter. What is your opinion, now, after our conversation on the subject? Ch. Matter is said to be infinitely divisible; and many are the arguments advanced in support of that hypothesis; yet, it can only be divisible as being composed of atoms; but an atom cannot be divided by any natural means.

Em. Is there, then, any difference between matter and body?

Fa. Yes: for although bodies are composed of matter, those terms are not strictly synonymous. Bodies are capable of being divided; because the atoms of which they are composed may, by various means, be separated. The attenuation of gold on wire, of which mention has been made, is not perhaps, strictly speaking, a division of matter, but of body.

Ch. Are bodies of themselves inactive, or inert?

Fa. They must be so until they are forced into action. It has been well observed, in elucidation of this fact, that a tranquil pool of water is inert; but when made to fall on a mill-wheel, it becomes an immensely active power.

1. Of what is every thing which we see and feel composed?

2. How is matter defined?

3. What are the essential properties of matter, and say what you understand by each ?

4. Can matter be divided into very minute particles?

5. Can you think of a particle so small

Joyce's Scientific Dialogues.

as not to have an upper and an under
surface?

6. If it has these, must it still be divisi-
ble?
7. In short do not some philosophers
conceive that it can be divided without
end?

8. What length of thread did the lady
spin out of a single pound of wool?

1

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16. Are not millions of insects found in a single drop of liquid?

17. Must not parts of these creatures be inconceivably sinali?

18. Tell me about the piece of sugar in the tea, the drop of wine in the tumbler of water, the grain of copper in the nitric acid.

19. What do you understand by ultimate particles?

20. Explain to me the difference between matter and body.

21. Is not the earth where we live teeniing with wonders?

22. Must not the great Being who made, supports, and governs all things, be worthy of all love and praise?

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TUTOR. Come: the tea is ready. Lay by your book, and let us talk a little. You have often assisted in making tea, but perhaps have never considered what kind of an operation it is. Pupil. An operation of cookery, is it not?

T. You may call it so; but it is properly an operation of chemistry.

P. Of chemistry! I thought that that had been a very deep sort of a business.

T. O there are many things in common life that belong to the deepest of sciences. Making tea is the chemical operation called infusion, which is, when a hot liquor is poured upon a substance in order to extract something from it. The water, you see, extracts from the tea-leaves their colour and flavour.

P. Would not cold water do the same?

T. It would, but more slowly. Heat assists almost all liquors in their power of extracting the virtues of herbs and

other substances. Thus, good housewives were formerly used to boil their tea, in order to get all the goodness from it as completely as possible. The greater heat and agitation of boiling makes the water act more powerfully. The liquor in which a substance has been boiled is called a decoction of that substance.

P. Then we had a decoction of mutton at dinner to-day. T. We had broth is a decoction, and gruel and barleywater are decoctions.

P. And ink

T. No-the materials of which ink is composed are steeped in a cold liquor, which operation is termed maceration. In all these cases, you see, the whole substance does not mix with the liquor, but only part of it. The reason of which is, that part of it is soluble in the liquor, and part not.

P. What do you mean by soluble ?

T. Solution is when a solid put into a fluid entirely disappears in it, leaving the liquor clear. Thus, when I throw this lump of sugar into my tea, you see it gradually wastes away till it is all gone, the tea remaining as clear as before, though I can tell by the taste that the sugar is dispersed through all parts of it. The body which thus disappears, is said to be soluble, and the liquor it dissolves in, is called the solvent, or menstruum.

P. Salt is a soluble substance.

T. Yes. But what if I were to throw a lump of chalk into some water?

P. It would make the water white.

T. While you stirred it—no longer; afterwards it would sink undissolved to the bottom.

P. Chalk, then, is not soluble.

T. No, not in water; when stirred up in a liquor so as to cause it to lose its transparency, it is said to be diffused. Now, suppose you had a mixture of sugar, salt, chalk, and tea-leaves, and were to throw it into water, either hot or cold; what would be the effect?

P. The sugar and salt would disappear, being dissolved. The tea-leaves would yield their colour and taste. And the chalk

T. The chalk would sink to the bottom with the tea-leaves, unless the water were stirred, when it would be rendered turbid or muddy. After the operation, the tea-leaves, if dried

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