Hatcher’s Notebook – A Standard reference Book for Shooters, Gunsmiths, Ballisticians, Historians, Hunters and Collectors, by Julian S Hatcher, can be found here: https://archive.org/details/Hatchers_Notebook/mode/2up
Chapter 13: Notes on Gunpowder found here: https://archive.org/details/Hatchers_Notebook/page/n307/mode/2up gives a detailed explanation of how smokeless gunpowder is made, right down to the correct proportions to determine burn rate and pressures.
I suggest downloading a copy to save to your computer.
Didn’t have to sign up here:
https://www.tngun.com/wp-content/uploads/Hatchers-Notebook.pdf