ABSTRACT
The constant demand for products such as liquid fuels is a major driving force behind the
petroleum industry. Other products such as lubricating oils, waxes, and asphalt have also
added to the popularity of petroleum as a major resource. There have, however, been many
changes in emphasis on product demand since petroleum first came into use some five to six
millennia ago (Table 26.1) (Chapter 1). It is these changes in product demand that have been
largely responsible for the evolution of the industry from the demand for asphalt mastic used
in ancient times to the current demand for gasoline and other liquid fuels.
