Old Baking Books Free at Openlibrary.org
There are many old baking books in e-formats at the Openlibrary.org
Here are some interesting ones I found that you can read online
or downloaded for free in various formats such as PDF, EPUB, MOBI, etc.
Ryzon Baking Powder Baking Book 1916 - with color illustrations
http://openlibrary.org/works/OL1472910W/Ryzon_baking_book