Ethylbenzene occurs naturally in coal tar and petroleum. Petroleum-derived naphthalene is usually purer than that derived from coal tar. There is also petroleum in oil sands (tar sands). Most naphthalene is derived from coal tar. Coal tar pitch is often confused with asphalt and asphalt with coal tar pitch. It is a component of coal tar. Coal tar and salicylate derivatives are often used as well. Naphthalene is the most abundant single component of coal tar. Historically, pyridine was produced from coal tar. This chemical is a product of creosote, a type of tar. Other particulates may be composed of drops of condensed tar, or solid particles of ash. PAHs are uncharged, non-polar molecules found in coal and in tar deposits. These include moisture content, ash content, sulphur content, volatile content, tar, and plasticity. As well as gas, coke, tar and tar paint were produced. The railroad shipped products such as lumber, tar, and tobacco.