The tertiary amine oxide compounds useful in this invention must have two alkyl chains having at least 8 carbon atoms and no more than 18 carbon atoms, and have the formula ##STR2## wherein R5 and R6 are straight and branched chain alkyl radicals having from 8 to 18 carbon atoms, and R7 is a lower alkyl group having from 1 to 4 carbon atoms, and preferably is methyl.