Remember petroleum ether is not a true ether its a mixture of hydrocabons like refined crude oil.
True ethers are so flamable that they don't need oxygen to burn because they have oxygen attached to them already. For instantance diethyl ether CH3CH2OCH2 CH3 that oxygen on the two ethyl groups make it fucking explosive like a motherfucker. I feel sorry for the retard who flicks his cigarett near a can of ether. Not to mention that it will form peroxides (CH3-O-O-CH3) with oxygen which can cause a chain reaction and explode violently under garage conditions. Just be fucking careful we don't want the FBI reading this shit do we. P.S. I hate Terrorists.