The

species. The hyacinth is sometimes of a deep red, and sometimes of a yellow color. amethyst is of a bright purple. The emerald a grass green. The beryl of a sea green. The sapphire, a sky blue. or chrysolite, is of a gold color. found in India and Brazil, and are all transparent.

or blueish The topaz These are

There are others that are opaque, or only half transparent; such as the cornelian, which is the best, and of a pale red, sometimes bordering upon orange; the onyx, of a greyish cast; the torquois, something between a blue and green; and the lapis lazuli, which is studded with spots of gold, on an azure ground.

OF THE LOADSTONE.

2. What is the magnet or loadstone ?

A. This wonderful stone is usually found in iron mines, and is produced in most parts of the world; in China, Bengal, Arabia, Hungary, Germany, and England. It is a heavy stone, something resembling the ore of iron, only closer and more ponderous.

It is endowed with some surprising qualities and powers. It attracts iron, which will adhere to it very strongly; and this virtue is also communicated to the iron so attracted. In every magnet there are two poles, one of which points northward, the other southward; and if the magnet be divided into ever so many pieces, the two poles will be found in each piece.

It is this property which has rendered it so useful in improving the art of navigation; for this gave rise to the mariner's compass; by means of which, a mariner can now conduct his

ship to the East or West Indies, or even round the world, with as much ease, and as little danger, as he could formerly make a voyage along

the coast.

2. Have the improvements in ship building, kept pace with those in navigation?

A. They no doubt have. To be convinced of this, one need only consider the infinite difference there is between a first rate man of war, and an Indian canoe, which seems to be little better than a large butcher's trough; and yet this was probably the first form of all sailing vessels.

Even after men had learned to build ships with more art and of a larger size, they never ventured out of sight of land without fear and trembling; because they could not tell whether they were sailing east or west, north or south, or to what part of the world they were going; but now, by the aid of the magnet or loadstone, in the darkest night, and in the midst of the boundless ocean, they know the course they are steering, with as much certainty as if it were in broad day, and within sight of land.

CLASS X....LESSON V.

CHEMISTRY.

2. CHEMISTRY appears to be now talked of more than any other science, will you give me some account of it?

A. It merits all the attention bestowed or that can be bestowed upon it, for it is the key-to many other sciences, and has produced a more accurate knowlege of the operations of nature than was ever before known.

2. What is its object?

A. The object of chemistry is to ascertain the properties of which all bodies are composed, and the manner in which they are combined with each other, and the properties they acquire by combination. Within the last 30 years only it has been carried to the greatest perfection, and the vast discoveries which it has led to, has not only rendered a new language necessary for the science, but it has exploded many principles as false, which were before considered as fixed.

2. What is the best course to be pursued to obtain a correct knowlege of chemistry?.

A. To take it up in small distinct parts, and pursue it step by step to greater extent; it may for this purpose be distributed into four branches. 1. What relates to simple bodies. 2. Compound bodies of two properties. 3. Compound bodies. of more than two. 4. Bodies as they appear in the animal, vegetable, and mineral economy of

nature.

2. What do you call simple bodies?

A. Such bodies as have not been decompounded or reduced to more than one peculiar property, they are divided into six classes. 1. Oxygen. 2. Simple combustibles. 3. Metals. 4. Earths. 5. Caloric. 5. Caloric. 6. Light.

2. Here I find some words that are new to me, but as you have said the knowlege of a science is the knowlege of the language of that science, pray what is the meaning of the word or nature of the simple body called Oxygen?

A. This substance was discovered by Dr. Priestly in 1774, and is named from two Greek words, signifying the property that produces acidity, because one of its qualities is, when combined with certain substances, to produce various acids, and such substances are called the bases of the acids so produced.

2. Give me some example of this operation?

A. Take a glass tumbler and place some fresh leaves of any plant in it, then invert the tumbler in a bason of clear water, and expose it to the rays of the sun, there will appear to issue from the leaves through the water into the vacant part of the inverted tumbler, numerous bubbles of air, which collect in the top of the tumbler,. and these are found to be oxygen gas, or oxygen in an aeriform state. The same kind of gas or air is produced by heating nitre in close vessels.. Oxygen is absorbed by combustible bodies, and converts them into acids. It is essential to the process of combustion, as it unites with bodies that burn, and encreases their weight and changes their properties. It is also essential to respiration, as no animal can live in air which is de prived of oxygen.

2. What do you call caloric?

A. It has been very common to confound cause with effect; and thus light has been frequently treated as proceeding from the same cause as heat; so, also, as was observed by the immortal Locke, when near the fire, we feel the sensation of heat, and then say the fire is hot.... when in fact, there is no more heat in the fire, than there is pain in the needle that pricks the finger caloric, then, is that matter in nature, which is the cause of heat....as oxygen is the cause of sourness, or acidity.

2. How is this exemplified?

A. Dr. Franklin, in one of his letters, thus explains it: "While I am writing, part of my hand rests on the green cloth, and another, on the brass lock of my desk; the cloth and the lock are undoubtedly of the same temperature; yet the part of my hand which is on the lock, feels colder, and really is so, than the other part that rests on the cloth; this is because the metal is a better conductor, and carries off the heat from my hand." The cause of this difference then, was, that the metal conducted the caloric out of the body, more than the cloth, and the cause of heat being withdrawn, the body from which it was withdrawn, became cold.

2. What are the simple combustibles?

4. Substances capable of burning, which is combustion, there are five. 1. Sulphur, a hard brittle yellow substance without smell unless it is heated, and almost without taste. It is found both pure and mixed; and by means of fre may be converted into an acid. 2. Phosphorus, which is never found in a pure state, but asually united with oxygen, and it is then called