No sooner do I post Ada Bixby's Sponge Cake recipe than I come across another entitled: TRUE SPONGE CAKE.
The provenance of the handwriting is uncertain at this point, but it's a more recent scrap of paper than Ada's version.
"True Sponge Cake
5 egg whites
5 egg yolks
1 cup sugar
1 cup flour sifted 4 times
1/4 teaspoon salt
1 tablespoon lemon juice
grated rind 1/2 lemon
Beat whites stiff not dry, beat in half the sugar. add lemon rind, juice to yolks and beat until [thick] and lemon color. Beat in rest of sugar, combining mixture. Cut and fold w/ flour sifted with salt, pour into unbuttered pan, Cut thru mixture several times to break bubbles. Bake 1 hour or more in moderately slow oven (325 degrees F) . If in deep pan (350 degrees F)."
Due to eggs being larger today, a modern adaptation of this would probably call for 3-4 eggs, rather than 5.
If a word is in [brackets] then I'm not sure I've transcribed it correctly. If you have a better guess, let me know!