Combine sugars, water, corn syrup and salt in 2-qt. heavy saucepan. Cook, stirring constantly, until sugars dissolve and mixture reaches a boil. If sugar crystals form on sides of pan, wipe them off. Continue cooking, without stirring, at a fairly low boil to the hard ball stage (260°). Remove from heat.
At once beat egg whites until stiff. Pour hot syrup in thin