I have a small Hershey's 1934 cookbook. It has several icing recipes in it. This is one of them. Don't know if its what you are looking for though. The picture of this icing in the book is a very light brown in color. I am copying it as printed in the book.
Fluffy Chocolate Icing
1 cupful granulated sugar...1 cupful water...pinch cream of tartar...2 egg whites...1/4 cupful Hershey's Cocoa...1/2 teaspoonful vanilla.
Dissolve the sugar in the water,and add the cream of tartar. Boil to the soft ball stage. (A small amount of mixture forms a soft ball when dropped into cold water, 234 degree F.) Beat egg whites until very stiff, then pour syrup in thin stream over them, beating all the time. Continue to beat until frosting is cool and of right consistency to spread, about 10 minutes. Carefully fold in cocoa and vanilla.
Yeild: About 2 and 1/2 cupful icing or enough for an 8- or 9 inch layer cake.
There is anothe recipe for icing called Aunt Jessies Chocolate Icing. It is the recomended recipe to go with the Hershey's Special Cake. This recipe calls for 2 squares Hershey's baking chocolate. If you are interested I can print that one too.
dawnj