The Third Step (Acid Wash) is to remove free iron, metallic residues, oxides, and other corrosion products from the surface of the metal.

The concentrations of individual free animo acids in heart, brain, lung, stomach, gut liver, spleen, kidney, and muscle tissues from 10 fetuses were determined with amino acid autoanalyser.

When scientists pretreat neurons with this acid in the lab, the cells are significantly (though not completely) protected from free-radical damage. Yup: Coffee is a good source of antioxidants.