I've happened across your post somewhat belatedly, but to build on what others have written, this is a fine example of a French notarial register. I have a similar one from the 1580s, bought on eBay, that I've been researching and reading. My understanding is that notaries drafted legal documents in books like this before copying the texts onto vellum for the parties to keep. Based on what I can see in your photos, you have a nice range of document types: a purchase ("achapt"), a will ("testament"), and so on. Some start with conventional formulas ("A nom de Dieu soit / a tous presens et advenir..." = "In the name of God, Amen; to all present and future..." etc.), while others begin with a date ("Lan mil cinq cens quatre vingtz quinze....." -- "In the year 1595....," etc.), if that helps you at all with decipherment.