cor. sub.: “corrosive sublimate” (mercuric chloride). sal. am.: “sal ammoniac” (ammonium chloride).

TJ composed this document no earlier than 29 May 1818, when he received the unrelated letter at the bottom of which he jotted these notes. He may have written them in connection with a painful infection on his buttocks contracted that summer at Warm Springs (MB description begins James A. Bear Jr. and Lucia C. Stanton, eds., Jefferson’s Memorandum Books: Accounts, with Legal Records and Miscellany, 1767–1826, 1997, The Papers of Thomas Jefferson, Second Series description ends , 2:1346). TJ’s calculations could derive from a recipe for “Itch Lotion” found on p. 312 of James Ewell, The Planter’s and Mariner’s Medical Companion (Philadelphia, 1807; Sowerby, description begins E. Millicent Sowerby, comp., Catalogue of the Library of Thomas Jefferson, 1952–59, 5 vols. description ends no. 893): “Take of Corrosive sublimate, one drachm; Crude Sal Amoniac, two drachms; Water, one pint and a half. Mix.” A recipe differing only in specifying one quart of water appears on p. 607 of the 5th ed. of Ewell’s work, entitled The Medical Companion (Philadelphia, 1819; Poor, Jefferson’s Library description begins Nathaniel P. Poor, Catalogue. President Jefferson’s Library, 1829 description ends , 5 [no. 183]), a copy of which TJ received from the author late in 1819 (Ewell to TJ, 12 Oct. 1819; TJ to Ewell, 7 Nov. 1819).