Potassium hydroxide is similar to sodium hydroxide but is a
stronger base; it is also more soluble in alcohol and the solution is
sometimes used as a reagent ('alcoholic potash5). The other hydroxides
of Group I are similar, increasing in base strength down the
group*; all are hygroscopic solids which attack the skin- hence the
old names, "caustic soda' (NaOH), "caustic potash' (KOH)—and
react with carbon dioxide in the air to give carbonates: