Are lipids soluble in water or petroleum ether?

Since fatty acids have a tail that dissolves well in oil and a head that dissolves in water, they make good soaps. It's possible to produce free fatty acids from triglycerides, which are animal fats, by reacting triglycerides with lye or base. This results in a foamy mixture of fatty acids.

The fatty acids stick their tails in grease or oil, surrounding the grease, while the water soluble heads remain outside the grease or oil. This creates a grease emulsification, meaning drops of oil end up surrounded by fatty acids, and suspended in water. In this way, soap helps to wash grease off surfaces.