A Leather Scroll is a skin prepared for writing, and the start of the whole paper chain. At the Writing Desk one Skin of any kind becomes 4 scrolls (6 with the Paper maker perk), with the Writing Basic technology and Book writing mastery 1. One scroll then becomes 6 Clean Paper.
Scrolls also bind notebooks (one scroll and 4 paper make 2), and they are the leather in the Butcher’s Kit and the two better surgical kits, the Bellows and the Smithy’s bellows. The town Alchemist sells them at every tier, 20 in stock.