A great advocate of the sciences, President McCosh addressed the overcrowding of the John C. Green School of Science by initiating plans in 1885 for a new chemical laboratory. Although a variety of delays prevented the building from opening until 1891, the laboratory was truly a McCosh project and constituted his parting gift to the sciences.
Funded by the estate of John C. Green -- and last of Green's legacies to Princeton -- the new laboratory was built on a symbolically important site: on Nassau Street, on the east side of Washington Road. It was the first academic building built east of Washington Road, and represented Princeton's increasing need to expand beyond the traditional confines of the campus.
Richard Morris Hunt, the architect of Marquand Chapel, consulted
extensively with Professor Henry G. Cornwall of the School of Science in
designing the Chemical Laboratory. He produced an L-shaped building, with legs
extending 101 feet along Nassau Street and 108 feet along Washington Road. The
two legs were 42 and 53 feet wide, respectively.
Executed in the Renaissance Revival style popular in the 1890s, the top floors of the Chemical Laboratory were made of Haverstraw brick laid in red mortar. The ground floor was Trenton sandstone, as were the belt courses and window trimmings. It featured a flat roof with mock battlements.
Inside, the Chemical Laboratory housed a large lecture hall on the first floor and two laboratories on the second floor. The ground floor held a laboratory for assaying metals and rooms for gas analysis, metallurgy, and technical drawing. For fireproofing, the Laboratory had iron floor beams and brick partitions.
In 1929, the Chemistry Department moved to its new quarters in Frick Hall, and the Chemical Laboratory was taken over by the School of Engineering, then housed in Green Hall (1927). The building was renamed Green Annex until 1977, when its named was changed to Aaron Burr Hall, to honor the College's second president.