Boil butter in a generous amount of water thoroughly. Cool, remove from the top of the water and drain.
Pasteurize sweet cream the same as milk, cool quickly, let stand covered in a cold place for at least 4 hrs; whip or beat in a deep vessel, the inner cup of a double boiler or a pitcher, (some think it easier to shake the cream in a tightly corked, wide mouthed bottle or jar) until like whipped cream; then set the dish in slightly warm water, to raise the temperature of the cream enough to cause the butter to separate but not enough to make it oily. Remove the dish from warm water just as soon as butter begins to separate; pour off buttermilk and pour pure cold water over the butter. Work a little and pour water off; next pour on water with a little salt (1 teaspn. to the quart) and let it stand from 10 to 15 m. Remove butter to cold dish, add salt, about 1/2 tablespn. to the pound, if unsalted butter is not preferred; work a little, cover with a cloth wrung out of salt water, and let stand a few hours in a clean airy place. Then work a little and shape as desired. Do not work enough to spoil the grain and make the butter oily.
This is the method with which I have had the best success. The regular temperature for churning cream is from 58 to 60 degrees by the thermometer. Sterilized butter should be made fresh every day.