The economic potential for the internal-combustion engine lay in need for a light locomotive engine. This could not be provided by the gas engine -including a piped supply of town gas-any more other than the steam engine combined with a cumbersome boiler. Using alternative oil fuels, the internal-combustion engine took to wheels, with momentous consequences. Bituminous deposits had been known in Southwest Asia from antiquity and utilized for building materials, illuminants, and medicinal products. The westward expansion of settlement in America, with many homesteads beyond the range of city gas supplies, promoted the exploitation of the readily available sources of crude oil to manufacture Kerosene (paraffin). In 1859, the oil industry took a new leap when Edwin L. Drake bored successfully through 69 feet (21 metres) of rock to strike oil in Pennsylvania, thus inaugurating the search for and exploitation of the deep oil resources of the world. While global oil supplies expanded dramatically, the bulk demands were for Kerosene, the middle fraction distilled from the raw material, which was used as fuel in oil lamps. The most volatile fraction of the oil, Gasoline, remained an embarrassing waste product until it was discovered that this could be burned in a light internal-combustion engine; the result was an ideal prime mover for vehicles. The path way for this development was shown by the success of oil engines burning cruder fractions of oil.
The greatest refinements in the heavy-oil engine are associated with the work of Rudolf Diesel of Germany, who took out his first patents in 1892. Working from thermodynamic principles of minimizing heat losses, Diesel devised an engine in which the very high compression of the air in the cylinder secured the spontaneous ignition of the oil when it was injected in a carefully determined quantity. This ensured high thermal efficiency, but it also necessitated a heavy structure because of the high compression maintained, and a rather rough performance at low speeds compared with other oil engines. It was therefore not immediately suitable for locomotive purposes, but Diesel went on improving his engine and in the 20th century it became an important form of vehicular propulsion.
Industrial organic chemistry today can be divided roughly into four major areas. In order of their current economic importance they are polymers, petrochemicals, synthetic materials (other than polymers), and miscellaneous organic materials lumped together under the general heading of “fine chemicals”. The historic development and present industrial structure of each of these are different.
Natural gas and petroleum are chief sources of aliphatic hydrocarbons at the present time, and coal is one of the major sources of aromatic hydrocarbons. Petroleum is a dark, viscous mixture of many organic compounds, most of them being hydrocarbons, mainly alkanes, cycloalkanes and aromatic hydrocarbons. It occurs deep below earth’s crust entrapped under rocky strata. It is taken out by drilling wells. The natural oil thus derived is a viscous black liquid. In its crude form, the oil is called Petroleum (Latin, petra-rock; oleum-oil) or Crude oil as it is found in abundance near oil wells, is referred to as Natural gas. Natural gas is primarily a mixture of the surface of the earth trapped by rock structures. The gas, which flows out naturally methane, ethane, propane, butane, Cs-Cg alkanes along with nitrogen.
Petroleum may exist in gaseous, liquid, or near-solid phases either alone or in combination. The liquid phase is commonly called crude oil, while the more solid phase may be called bitumen, tar, pitch, or asphalt. When these phases occur together, gas usually overlies the liquid, and the liquid overlies the more solid phase. Occasionally, petroleum deposits elevated during the formation of mountain ranges have been exposed by erosion to form tar deposits. Some of these deposits have been known and exploited throughout recorded history. Other near-surface deposits of liquid petroleum seep slowly to the surface through natural fissures in the overlying rock. Accumulations from these seeps, called rock oil, were used commercially in the 19th century to make lamp oil by simple distillation. The vast majority of petroleum deposits, however, lie trapped in the pores of natural rock at depths from 150 to 7,600 metres (500 to 25,000 feet) below the surface of the ground. As a general rule, the deeper deposits have higher internal pressures and contain greater quantities of gaseous hydrocarbons.
Petroleum and natural gas are generally considered to be formed by the decomposition of plants and microscopic animals when buried under earth under geological conditions for a long period of time at high temperatures and pressure and in the absence of oxygen or with little oxygen. Natural gas and petroleum, therefore, are known as fossil fuels. It seems probable that petroleum and natural gas are being formed at the present time. However, the rate at which these natural resources are being used up is very much greater than the rate at which they are formed. Petroleum constitutes the principal energy source for our modern industrial society. It is the major source for most of
the chemicals used to form synthetic fibres, plastics, films, drugs, food additives and pesticides. Industry, agriculture, communication and means of transportation in the present-day world depend largely upon this ‘black gold’. In fact, it is the most valuable material for nations in peace and war. A statesman has observed, “The nation that has petroleum dominates world politics”.
