Preheat oven to 350�F.
In a bowl, sift the flour, 3/4 cups of sugar, and salt together.
In a large bowl, beat egg whites, water, lemon juice, cream of tartar, and vanilla extract using a handheld electric mixer. Beat until a soft peaks form and then decrease mixing speed. Slowly add the rest of the sugar a little at a time while mixing.
Sift small portions of the dry flour mixture into the wet mixture. Fold the dry mixture into the wet mixture. Repeat until the mixtures are evenly combined.
Coat a 10 inch baking pan with cooking spray and then pour the batter into it.
Bake for 35-40 minutes or until an inserted toothpick pulls out clean. Allow cake to cook before serving.
