rbon atoms; x is 1 when Y is a sulfur atom and 2 whenY is a nitrogen or phosphorus atom, R is an alkylene or hydroxy alkylene group of from 1 to about 4 carbon atoms and Z is a member selected from the group con s'isting' of carboxylate, sulfonate, sulfate, phosphonate, and phosphate groups. p Examples includei I 4-[N,N-di(Z-hydroxyethyl)-N-octadecyl-ammonio]- butane-l-carboxylate; 5-[S-3-hydroxyp