A bain-marie is a large vessel of hot or boiling water, in which saucepans, kettles, moulds, etc., are placed to prepare or warm food. It is also used to keep any kind of food warm, when something is ready to serve, and the time has not come; the utensil containing it is placed in hot water, and it not only keeps it warm, but there is almost no evaporation while in it. It does not boil away either.
There are things that are much more delicate when prepared or warmed in hot water.
One utensil made for that purpose, and of brass, with compartments, is more handy, but a large saucepan may be used in its stead.
When any thing is in the bain-marie, the water should not be allowed to boil fast enough either to upset the pans or get into them.