Petroleum Ether 60-80. Petroleum ether, also known as pether, benzine, VM&P naphtha (varnish makers’ & painters’), petroleum naphtha, naphtha ASTM, petroleum spirits, X4 or ligroin, is a group of various volatile, highly flammable, liquid hydrocarbon mixtures used chiefly as nonpolar solvents. Chemically, it is not an ether like diethyl