Beat egg whites and vanilla till stiff and egg whites form peaks
when beaters are lifted from mixture.
Combine granulated and brown sugar, water and salt in 1 quart sauce
pan. Place over heat, stirring constantly until sugar dissolves.
Bring to a boil and stop stirring. Boil till mixture reaches 246
degrees on the candy thermometer. Slowly beat hot syrup into egg
Continue beating until frosting reaches desired spreading consistency.