The series holds many of Percival's financial papers documenting his payments for room, board, clothing, laundry, and other expenses, including his agreement with the General Hospital Society of Connecticut, where Percival lived from 1843 through 1851. Prominent among the papers are records related to his large collection of books: almost one hundred leaves of book inventories, more than twenty leaves of organizational schemes for the volumes, over eighty receipts from booksellers in Philadelphia, New York, Boston, and New Haven between 1819 and 1841, and insurance papers covering the collection. Also here are agreements regarding his publications, and a few general financial records. Other records for his publications and library are in Series II, Box 7, folder 140.