How is tar made?
Tangy black tar is also called asphalt. It is a free gift from the solid earth, and we do not have to make it. In certain places, it oozes up from the ground and spreads over the earth in tacky black pools and puddles. In tame, the sticky stuff dries into solid layers. We can dig it up and use it to cover roads and do dozens of other useful jobs. Under a tar pit there is a supply of petroleum, the oil from which we get gasoline and countless other valuable materials. Petroleum tends to evaporate in the air. It loses some of its gases and lighter liquids. The stuff that remains is tar or asphalt. When petroleum is near the surface, it may seep out and run over the ground.
