I love old cookbooks. My last purchase was a reprint of the 1887 White House Cookbook. The old books have the recipes we will need for making anything from glue to medicine, not just food. I have even seen some that even go through butchering the animal and how to do it included. They are a great resource for knowledge, even though some things have been proven to be wrong much of the information is good. Example… in my reprint there is a recipe for canning strawberry jam. Back then lids were not as common as today. The recipe says to spread egg whites on brown paper (my guess paper bag thickness) place it on the jar and tie it with a bit of string. When the egg white dries it seals the jar and keeps bacteria out, even if they are thickly covered with mold on the outside later on…. I never would have thought of egg whites as a sealer.