In heavy saucepan, mix milk, sugar, and salt. Heat slowly to boiling, stirring constantly. Cook to soft-ball stage, stirring often.
Remove from heat; add butter. Cool undisturbed for 20 minutes, then beat until candy thickens and begins to loose its gloss.
Quickly stir in pecans, and spread in buttered 8-inch square pan. Cool and cut. Makes about 1 1/2 pounds.
Variations: Mix 2 teaspoons instant coffee powder with sugar, or add 2 teaspoons grated orange peel while beating candy.