Are you a cook? a scientist? Then you probably know that a bain-marie (same in English) is a double boiler. It is used to melt ingredients for cooking, to heat materials gently to a fixed temperature or to keep them warm over a period of time.
The word comes from the Latin balneum Mariae, le bain de Marie, “Mary’s bath”. But what has Marie to do with it? Well, the invention of the bain-marie has been attributed to a Jewish alchemist named Marie (even though the technique had been known for centuries).