Serious Eats - seriouseats.com

All of my oldest cookbooks have come from my grandmother and great-grandmother. In fact, I just recently got a box out of storage filled with handwritten recipes and cookbooks that I need to sort through. But as of right now some of the oldest are:
The Boston Cooking School Cook Book, 1938
The Settlement Cook Book "The way to a man's heart", 1943
The Rumford Complete Cook Book, 1924...
An interesting side-note inside the Rumford book was a newspaper clipping article titled: "Says Cream of Tartar Will Cure Smallpox"
It also seems Rumford was also a chemical company and so the book has recipes like: "Acid Phosphate Whey"