Louis Hasbrouck was in his last year at Princeton in 1796-1797 when he attended the course of chemistry lectures given by John Maclean. In only his second year at Princeton, Maclean was rapidly becoming known for introducing the latest currents in chemical theory, including the system of Antoine Laurent Lavoisier, and he was one of the first Americans to insist that students take part in active experimentation. Louis Hasbrouck was in his final year at Princeton in 1796-1797 when he attended John Maclean's lectures on chemistry. His notebook from the second half of that course includes a detailed record of the lectures from January 24-March 14 and June 22-24, 1797, covering Maclean's discussion of the chemistry of metals, "chemical combination," combustion, and botanical chemistry. Although his notes are not complete, Hasbrouck was enrolled at a singularly interesting period in the history of American chemistry. This was only the second time that Maclean had offered his course, in which he introduced the new chemical system of Lavoisier, and it includes a relatively complete version of Maclean's most important lecture, "Of combustion." This devastating attack on Joseph Priestley and phlogistic theory appeared in print in 1797 as Two Lectures on Combustion: Supplementary to a Course of Lectures on Chemistry.

Principally covering botany and agriculture, this collection includes many manuscripts on trees, shrubs, and plants of different species, copies of botanical essays by others, essays on fruit trees, etc., by Auguste Denis Fougeroux de Bondaroy (1732-89), notes and drafts for the latter's revision of Duhamel's Traité des Arbres et Arbustres. Also miscellaneous essays, sketches, and memoranda on bones of birds and animals, electricity, fish, steam engines, ventilation, temperature and air pressure, mathmatics, paleontology ("Observations sur les os d'éléphants fossiles"), chemistry, metallurgy, entomology, architecture, taxidermy ("Méthode pour empailler les oiseaux"); lists of plants; notes on England, Canada, Mexico, China; notes of reading in Pliny, John Evelyn, Alexander Russell, William Derham, and others. An unpublished translation of Jethro Tull's Horse-Hoeing Husbandry, with additions and revisions by Duhamel du Monceau. An alphabetical catalogue of Duhamel's gardens, prepared by Fougeroux de Bondaroy. The collection has manuscript material in pre-publication form along with published material with marginalia for improvements of later editions. There are a multitude of sketches, botanical materials and seed packets. The collection includes lists of American trees and seeds shared with European scientists. Benjamin Franklin acts as a go between French and American botanists and John Bartram sends seeds to France from his garden. Also correspondence (ca. 170 pieces) with, among others, Peter Collinson, Duc d'Aven, Duc de Noailles, Louis J. M. Daubenton, Mathurin Jacques Brisson, Jean François Gauthier, Comte de La Galissonière, Chrétien Guillaume de Lamoignon de Malesherbes, Emerich Vattel. The collection has been described in part by Gilbert Chinard, "Recently Acquired Botanical Documents," APS Proc. 101 (1957): 508: and by Joseph Ewan, "Fougeroux de Bondaroy (1732-1789) and his Projected Revision of Duhamel du Monceau's Traité (1755) on Trees and Shrubs. I. An Analytical Guide to Persons, Gardens, and Works mentioned in the Manuscripts," APS Proc. 103 (1959): 807.