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.