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old pieces of decayed wood which gave light, that light is given by phosphorus.
Light shows us the things which are about us, and gives them color. Those things which can be seen are visible; those which cannot be seen are invisible. Men and houses are visible-air is invisible. Sight is vision. The light which we see comes from the sun, or from fires artificially produced. If the light comes straight to our eyes, it is direct-the light from the candle is direct.
If the light comes through any substance, it is refracted the light which comes through the glass window is refracted, or bent, and because it is divided-part of the light is on the outside of the window, and part on the inside-the window bends, or refracts the light.
The light which falls upon a substance and does not go through it, is turned back, or re flected. When the candle is held to one side of the looking glass, the light cannot be seen on the other. The mixture of quicksilver and tin foil, called an amalgam, on the back of the glass, prevents the light from going through it-the light is reflected.
The history of light and vision is called optics. The organ of sight is the eye. The an atomy of the eye is very curious. The little spot in the middle of the eye is the pupil; the colored circle which surrounds the pupil is the iris.
SUBSTANCES which have a sour taste are acids. Some substances added to acids, take the sour taste from them; these are Alkalies. When cream is sour, put a little pearl ash into it, and it is no longer sour. Pearl ash is an Alkali.
Pearl ash is made from the ashes of burnt wood. The ashes are covered with water; the water soon becomes of the color of coffee, it is strained off, and is called lye.
This lye is boiled till it evaporates; at the bottom of the vessel in which the lye is boiled, are found the crystals of pot ash; from the pot ash is made the fine and white Alkali called pearl ash and sometimes sal aratus.
BREAD is made of flour, water, yeast, and a little salt; when these substances are first mixed, the dough takes up a small space; in a short time it begins to swell, or rise, and in a few hours it is fit to bake. Flour and water, without yeast, is paste.
The motion and swelling caused by yeast, is fermentation.
Hops, malt, and water, make beer. What is called the working of beer, is fermentation. This produces yeast.
Fermentation-the motion and expansion of certain substances, produced by the mixture of them, which produce a new substance.
Look at the shoes on your feet. They are made of leather. Leather is the skin of dead animals with the hair taken off. There are two parts to your shoe, and two kinds of leather in it. The upper leather which covers the top of your foot, is of one kind, and the sole or bottom of the shoe is another. The upper leather of shoes is made of calf skin, or sheep skin, or seal skin.
The sole leather is made of the skin of the cow, or ox. After the butcher has killed the animal, he cuts off the skin, called the hide, and sends it to the tanner. The tanner throws it into a vat containing lime and water, which loosens the hair; afterwards he lays the hide on a block and scrapes it quite clean.
The hide is next spread with care in another vat, and is covered with a layer of ground bark. This bark is taken from the oak, or the hemlock tree. Another hide is laid upon the bark. The bark and hides are thus laid alternately, one upon the other, until the vats are filled. Water is poured into the vats, and penetrates the hides and the bark. When quite tanned the hides are taken out and dried; those intended for upper leather of shoes are sent to the currier, who finishes them for the shoemaker. The sole leather
is already fit for use. Almost all children have put alum into their mouths; they know that the the alum draws the skin of the mouth and makes it feel stiff-just so, the bark draws the skin, or sole leather. This property of some substances to draw up the parts of other things, and make them harder and thicker is astringency. Alum is astringent, and oak bark is astringent.
Tanned leather is used for the soles of shoes, aud some other purposes.
The currier, the tanner, and the shoemaker, are all obliged to labor for us before we can have shoes.
EAR RINGS are made of gold. Thimbles and spoons of silver. Cents are made of Copper. The horses' shoes are made of iron. Water pipes are sometimes made of lead. Candlesticks, pans, and watering-pots are made of tin ware. The back of the looking glass is covered with tin foil, and quicksilver.
These are all metals. Metals come out of the ground. People dig into the earth to find metals.
The place where metals can be found, is called a Mine. The metal is found in the mine, mixed with dirt, stones, and some other substances; when the metal is found, mixed in this manner, it is called an ore.
Gold is the heaviest of all metals, except platina. Gold weighs more than nineteen times as much as water weighs. That is, a cup full of gold would be heavier than nineteen cups filled with water. Platina is a metal not much used.
Silver is eleven times heavier than water.
Iron is eight times heavier than water.
Brass, of which knockers, bell handles, little thimbles, and a great many other things, are made, is itself made of copper and zinc, united with carbon, or charcoal, and made into different shapes. The copper and zinc are melted together and become brass. Bells are made of tin and copper.
Children often melt lead, and pour it into different shapes. If the melting lead is kept for a considerable time over the fire, a quantity of small scales may be perceived floating upon the surface of it; if the lead remain a long time upon the fire the whole of it will be changed to these scales; they will become a fine powder. The powder of burnt metals, (for all except gold and silver, may be burnt by long continued heat,) is called calx.
The plural of calx, is calces. The calces of lead, prepared in one way, become red lead; prepared in another way, they become white lead. The white paint which is put upon houses is a mixture of oil and white lead.
Meta's and glass are brilliant; that is, they shine when they are in the light. The light passes through glass; it is transparent.