Sue Singleton, age 11, of Milwaukee, Wis., for her question:
Where do we get asphalt?
Perhaps you have wondered why the body of an ancient pharoah is called a mummy. Well, the word comes from the Persian word mumia.. meaning asphalt. The ancient Egyptians used this dark mineral to preserve their dead. At about this time, the people of Mesopotamia were using asphalt to pave their roads, line their irrigation ditches and even water proof their temples. Most of these ancient supplies were taken from Asphaltis Lake, near the Dead Sea.
Today less than one percent of our asphalt comes from natural supplies. Most of it is processed from certain petroleums. These are the petroleums of California, the Gulf States and Mexico which have an asphalt base rather than a paraffin base. With heat, the gasoline, kerosene and other light chemicals are driven off from the petroleum and distilled for use. What remains is a tacky, brownish black mineral called asphalt, tar or pitch.
Petroleum, we suspect, forms from the fossil remains of ancient sea dwelling plants. Asphalt forms in nature where asphalt based petroleums occur near the surface of the ground. Left in the open air, a pool of petroleum tends to lose its lighter substances, much as it does when heated. In 1597, Sir Walter Raleigh found such a pool of asphalt near Trinidad. This pool, one of the world's largest natural supplies of asphalt, covers an area of 147 acres and at its center is 200 feet deep. Berimxdez Lake in Venezuela covers a thousand acres but is only two or three feet deep. Asphalt is cut from these deposits in large doughy strips.
Vein asphalt occurs in rock cracks and crevices. It is glossy black, hard and brittle.
This is the purest of all asphalts and is used in making fine varnishes and paints and to rust proof metals. We find this valuable mineral embedded in certain rocks in New Brunswick, Texas, Colorado and West Virginia. Bituminous rock, or rock asphalt, is formed when porous limestones and sandstones become steeped in asphalt. These rocks are often crushed to pave roads.
Many of our new super highways are paved with hard concrete. But four fifths of our roads are still paved with asphalt. This blacktop paving is durable and waterproof. It also 31ves a little under heavy traffic. Blacktop also makes a fine paving for air strips. Only five to ten percent of the black p4ving material is actually asphalt. The rest of the mixture is sand, crushed stone and fine gravel.
Asphalt shingles are prepared by soaking strips of felt or asbestos in liquid asphalt. Asphalt floor tiles are prepared in the same way. When properly laid, floors and roofs of asphalt tile are durable, firm and waterproof. Like the people of ancient Mesopotamia, we still use asphalt in irrigation. It ,is used to waterproof dams, tunnels and bridges. But, unlike the ancients, we do not have to rely upon natural supplies. Almost all our asphalt is taken from petroleum.