Gunpowder found in paper packages.

https://www.dailymail.co.uk/home/books/article-2282391/Explosive-story-big-bang-SALTPETER-THE-MOTHER-OF-GUNPOWDER-BY-DAVID-CRESSY.html;

The gunpowder, which includes two solid bars and numerous small paper packages, was found packed into an early 20th century stationery box.

https://www.theguardian.com/uk/2002/mar/22/humanities.research