blood than could be held in the little spot where you made the prick? In the same way the sap, which is the blood of the tree, rushes towards the puncture made by the insect. When this sap reaches the air, it thickens, just as the gum does when it comes out of the tree: and by degrees forms itself into a ball about the size of a cherry. The insect which makes this hole is a small fly with four wings. Those nuts which grow upon the oak are the best to make ink from. They contain a strong acid which is called Tannin. You know that the bark of the oak is used in turning the skins of animals into leather; and that when the skins are put to soak in water mixed with the bark, we say they are being tanned. We use this word because "tannin " is contained in the oak bark. "Logwood" comes from a very prickly tree, something like an Acacia, which grows in America. It has fine large yellow flowers, which grow in long drooping bunches. The trees are cut down and sawn into large blocks, which are sent to us in ships; then the people in this country cut them up into very small pieces and boil them, for the sake of the beautiful red dye which comes from them. "Sulphate of iron" is a compound of iron, sulphur, and oxygen. The last of these is part of the air which you are always breathing, and without it you could not live. For purposes of trade sulphate of iron is formed from what is is called "iron pyrites." This pyrites is a compound of iron and sulphur, and is found in many parts of the world. It is dug up out of the earth, and put into very large open tubs, where it is left for a long while, sometimes for a whole year; being frequently moistened with fresh water. During this process it takes up oxygen from the air around. It is then well washed in hot ley. (sometimes spelt lye), which is made by boiling wood ashes in water. It is afterwards boiled in water for a long time. The water goes off in vapour, and the sulphate of iron, or 66 green copperas," as it is commonly called, remains at the bottom in the form of crystals. It has a very salt, bitter taste, and is a poison. Mixed with certain vegetable matters, it is largely used as a black dye; writing ink is a compound of this kind. You must ask your teacher to explain the meaning of the hard words in this reading lesson. THE pencils called lead pencils are quite wrongly named, for there is not an atom of lead in them. The (so called) lead is really plumbago or graphite, a substance which is dug out of mines, and is a particular form of carbon. Charcoal is another form of carbon; and the diamond is another. The plumbago is sawn into small square sticks, which are afterwards enclosed in cedar-wood cases, to form the pencils which you use. There are various ways of making these cases; perhaps the simplest is the following: Strips of cedar-wood are prepared, of the proper size. Along the middle of each a small groove or furrow is cut, just large enough to receive one of the small sticks of plumbago. The sticks are then placed in the grooves, and over each is glued another and thinner strip of cedar. A square pencil is thus formed. These square pencils are afterwards rounded by means of a plane of suitable size and shape. Some pencils, to make them look smarter, are polished, and have the name of the maker stamped upon them in gold letters. The best mines for the substance of which these pencils are made are in Cumberland. A Frenchman, some time ago, found out a way of mixing certain substances together, so as to make pencils quite as good as those made from plumbago. His pencils, too, have this advantage, that they can be made just as hard or as soft as we want them to be. Clev-er-ly Quar-ries Thick-ness SLATE. SLATE is a kind of stone that is quarried out of the earth. The places out of which stone is dug are not called mines, we call them quarries. All slate is not quite of the same kind, but if you were to go into a quarry of the sort most in use, and were to stand close to a clear face of the slate rock, you would see that it is |
