Dissolve gelatin in 1/4 cup water and add 1 cup boiling water. Stir until dissolved. Add pineapple, sugar, salt and lemon juice. Stir and chill until about the consistency of egg whites. Beat 2 packages of Dream Whip stiff. Fold into chilled gelatin mixture (looks creamy).
Break cake into 1 inch pieces of smaller, put layer of cake on bottom of pan (9x13 inch). Pour layer of pineapple mixture, another layer of cake, rest of pineapple mixture. Beat other 2 packages of Dream Whip stiff and pour over cake. Sprinkle can of coconut over Dream Whip. Cover with foil and chill.
My grandmother used to make this. It's wonderful for the summer because it's so light and cool tasting. I've made it as a special treat for family and friends and have always received rave reviews. It's nice to see the recipe again. I've gone the lazy route and switched to Jello and Cool Whip. It doesn't taste the same but not bad either.