There are lots of old cookbooks that have been digitized by various people (libraries, Project Gutenberg, Google...) and are free to read and download. The problem is getting to know about their existence. I'll try to post the ones I saved. If you know books that are missing in this list then please reply with the links, so I'll edit this post and add them, thanks.
Acton Eliza - Modern Cookery for Private Families