The Kirwan Collection was part of the Philosophical Library which made up the oldest collections of the Salem Athenaeum and were the spoils of war.
According to the library's website: "The Philosophical Library was founded in 1781 from the spoils of war. The ship Pilgrim, a privateer sailing out of Beverly, captured the Duke of Gloucester, the first of her nine valuable prizes, on September 5 in the Irish Channel. The Duke of Gloucester had sailed for Bristol from Galway that same day with a load of kelp and the library of Richard Kirwan (1733-1812). Kirwan had recently been elected a Fellow of the Royal Society for his research in chemistry, and anticipated re-locating indefinitely from his family estate, Castle Cregg in County Galway, to London. His library was captured with the ship and the 116 volumes were transferred to the Pilgrim and subsequently auctioned on April 12, 1781 in Salem.
Reverend Joseph Willard of the First Church in Beverly learned of the Kirwan library and gathered a group of associates to pool resources to purchase the lot. Organized as the Philosophical Library, the volumes were circulated to members and remained at Willard's residence in Beverly until he was elected President of Harvard College, at which time the collection was transferred to Reverend John Prince at the First Church, Salem. Over time, members added the latest scientific works and serials, increasing the collection threefold. The costly serial subscriptions kept the annual assessments high, and were a contributing factor to the eventual decision to merge with the Social Library to form the Salem Athenæum."
Essex Institute Historical Collection Vol. 102, p. 26-36