What Is Crude Oil ?

There were few takers of the 19th century elixir that came to be called "snake oil." It was one of the less successful uses of petroleum, but not the first to claim healing properties. Ancient Persians, 10th century Sumatrans and pre-Columbian Indians all believed that crude oil had medicinal benefits. Marco Polo found it used in the Caspian Sea region to treat camels for mange, and the first oil