Place a skillet on the stove and add about 1/2 inch of water. Bring the water to a simmer. Have ready 1 1/2 quart saucepan. Place the butter in another saucepan and place it over very low heat. Set 1 1/2 quart saucepan in the simmering water in the skillet. Place the egg yolks in the saucepan. Add the cold water, salt and 1 tsp. lemon juice. Start beating the egg yolks with a wire whisk, stirring in a back and forth circular fashion, making certain that the whisk covers the bottom of the saucepan so the yolks do not stick. It is important that the heat beneath the saucepan be moderate. When the egg yolks become custardlike and thickened, start adding the melted butter. Continue beating, stirring constantly and vigorously, until all the butter is added. Add the remaining lemon juice and cayenne.