Acid Acid was a type of chemical compound that was caustic in nature . Natural occurrences . Acid , sometimes in large bodies , could be found on many planet s . The sea s of Marinus ( TV : " The Sea of Death " ) , 16 Alpha Leonis One ( PROSE : " Eternity Weeps " ) and Endpoint were all composed of acid . ( PROSE : " Hope " ) The planet Vortis also had pools of acid on its surface . ( TV : " The Web Planet " ) Skaro had a river of acid , where the Dalek Emperor attempted to kill Zeg . ( COMIC : " Duel of the Daleks " ) Lake Mono on the Gyre was composed of acid , where the humans put criminals to death by immersing them in it . Uses . Offensive purposes . Some species used acid as a method of killing . This could include regular weaponry or an impromptu defence . The First Doctor used a syringe of prussic acid to kill a Zilgan on the Sense Sphere . ( PROSE : " The Monsters from Earth " ) Eldrad developed an acid that neutralised the molecular bond in silicon - based lifeforms . When he returned to Kastria after his execution , Eldrad triggered a booby trap that fired a missile containing the acid upon him . Knowing there to be no antidote , he was forced to use the regenerator chamber . ( TV : " The Hand of Fear " ) An Eldrad them was restored from " the Watcher " was killed with an acid filled dart by that restored from the original Eldrad ' s hand . In turn , this Eldrad was killed with the same dart by Mulkris . ( AUDIO : " Eldrad Must Die ! " ) The calcium - based bodies of Raxacoricofallapatorian s were vulnerable to acetic acid . ( TV : " World War Three " ) On Raxacoricofallapatorius , criminals were executed by being dissolved in a vat of acetic acid while still alive . ( TV : " Boom Town " ) The Second Doctor defeated the Krotons by using sulphuric acid against them . ( TV : " The Krotons " ) The Second Doctor used a bottle of acid to drive off a panther that was threatening him . ( COMIC : " The Monsters from the Past " ) On Jaconda , Mestor ' s body was destroyed with a beaker of acid . ( TV : " The Twin Dilemma " ) On Earth , coronic acid was used against the Sontaran s Stike and Varl . ( TV : " The Two Doctors " ) Cassandra O ' Brien ' s surgeons used moisturisers filled with acid to defend her . ( TV : " The End of the World " ) Other uses . Acid was used in acid jar s , a power source reliant upon wind to produce usable energy . ( TV : " Frontios " ) The human s of Varos used acid as a method of body disposal . The Sixth Doctor escaped from being dissolved in an acid bath . ( TV : " Vengeance on Varos " ) The Mantis leader , in his attempts to learn the nature of the Doctor ' s TARDIS , had it submerged in a beaker of acid in his ship ' s lab . The acid had little effect on the TARDIS . ( COMIC : " Size Control " ) Other information . Acid was one of the few things which could prevent a Time Lord from regenerating . ( PROSE : " Night of the Humans " ) Diplosian s were allergic to citric acid . ( TV : " The Stones of Blood " ) In the 22nd century , an acid factory was located at St John ' s Monastery . To protect themselves from its effects , the miners wore acid suit s . ( TV : " The Rebel Flesh " ) Strax , another Sontaran , expressed a fondness for warfare that involved acid . ( TV : " The Crimson Horror " , " Deep Breath " )