Combine all ingredients except baking soda in a large heavy saucepan.
Cook over low heat, stirring gently, until sugar dissolves.
Cover and cook over medium heat 2 to 3 minutes to wash down sugar crystals from sides of pan.
Uncover and cook to soft ball stage (235°), stirring constantly.
Remove from heat, and stir in soda.
Beat with a wooden spoon just until mixture begins to thicken.
Working rapidly, drop by tablespoonfuls onto greased wax paper; let stand until firm.