Wash the rice in several changes of cold water. Drain the grains and dry them between sheets of paper toweling.
In a heavy 1-1/2-quart casserole melt the butter over low heat. Add the rice and heat it, stirring constantly until the grains whiten. Do not let them brown.
In a saucepan combine the milk with the sugar and salt, and scald it. Add it to the rice, stirring just long enough to blend. Let the milk bubble for a few seconds.
Remove the casserole from the heat and sprinkle the top of the rice and milk with nutmeg. Cover the container securely and set it in an oven preheated to 250° F.
Bake the pudding for 1-1/2 hours, or until it is firm and the grains of rice are very soft. Serve warm or cold.
Servings: 4