Clams for steaming should be bought in the shell and always be alive. Wash clams thoroughly, scrubbing with a brush, changing the water several times. Put into a large kettle, allowing one-half cup hot water to four quarts clams; cover closely and steam until shells partially open, care being taken that they are not overdone. Serve with individual dishes of melted butter. Some prefer a few drops of lemon juice or vinegar added to the butter. If a small quantity of boiling water is put into the dishes, the melted butter will float on top and remain hot much longer.