The Handyman's Pocket Book: Cleaning Leather Coverings.

Real leather can be cleaned by sponging with a weak solution of borax and warm water.  Rub with a soft duster, and when dry polish with a chamois leather on which a few drops of glycerine has been sprinkled.  Rub with a circular movement to avoid streaks.  Grease spots can sometimes be removed by rubbing gently with a rag damped with benzine.