Substance used to accelerate a process (as the spreading of a fire).

Any chemicals that can help a fire grow... gas wax napalm keroscene diesel fuel

A fast pachyderm?

Gas, kerosene, oil, nail-polish-remover, hair spray, paint, etc.

A substance, such as a petroleum distillate, that is used as a catalyst, as in spreading an intentionally set fire. http://www.thefreedictionary.com/accelerant

"Accelerants play a major role in Chemistry. Every compound, chemical change, reaction..so on, can be, and in most cases is, modified with an accelerant. The word it self has the same meaning in any subject, to accelerate. In chemistry, you can use accelerators to alter a chemical or chemical bond, speed up a chemical prosses, bring organisms back to homeostasis, its endless what you can do with the right chemical accelerator. A accelerator isnt excactly a set thing, it can be anything, a substance that can bond, mix, or disturb another substance and cause a increase in the speed of its natural, or unatural chemical prossess." "Fire investigation: Indicators of an incendiary fire or arson can lead fire investigators to look for the presence of accelerants in fire debris. Accelerants can leave behind evidence of their presence and use. Accelerants present in areas they should not be can indicate an incendiary fire or arson. Investigators often use special dogs known as accelerant detection canines trained to smell ignitable liquids. The dog can pinpoint areas for the investigator to collect samples. Fire debris submitted to forensic laboratories employ sensitive analytical instruments with GC-MS capabilities for forensic chemical analysis." Source and further information: http://en.wikipedia.org/wiki/Accelerant