Series IV, E.I. du Pont de Nemours & Company and du Pont family miscellany consists of a variety of materials relating to the business and personal affairs of the du Pont family. These include incorporation papers and partnership agreements for the formation and merger of the various du Pont firms (1801-1914), including the ancillary textile and leather operations. Also included in this series are legal papers concerning the suit of Peter Bauduy (1769-1833) vs. E.I. du Pont de Nemours & Co.; fragmentary early accounts on the sale and shipment of powder; Henry du Pont's (1812-1889) accounts as supervisor of roads for Christiana Hundred (1842-1843); a collection of patents and related correspondence concerning electrical blasting apparatus and other inventions of Henry Julius Smith (1844-1901); formulas for smokeless powder; inventories of the New Orleans powder factory of J. C. Dalmas (1776-1859) and Charles François Parent from 1808; weaver's books of Du Planty, McCall & Co. (1817-1819); time books and account books of Samuel Kirk for the building and operation of the Barley Mill near Wilmington, Delaware (1825-1827); miscellaneous reports of the Industrial Relations Department of the DuPont Company (1928-1936); rules of the Gunpowder Trade Association; testimonials and awards given to the DuPont Company (1920-1939).

Series IV also contains typescript histories of several powder companies later absorbed by DuPont, including the Hazard Powder Company, the Laflin & Rand Powder Company, the Phoenix Powder Manufacturing Company, and a diary of the Repauno Chemical Company (1882-1893). Other historical scripts include notes on the use of high explosives in blasting rocks at Hell Gate in New York City, on the manufacture of black powder in the first DuPont mills, and on the early DuPont Conestoga powder wagons. Du Pont family miscellany describes E. I. du Pont's interest in botany and breeding Merino sheep. Notes on Lammot du Pont (1831-1884) include his trips to purchase saltpeter in England during the Civil War. There is also a biographical note on John Harrison (1773-1833), a Philadelphia chemist, along with one of his day books recording the sale of drugs and other medical supplies to Philadelphia area physicians and hospitals.

The Repauno Chemical is represented by a scrapbook with parchment and paraffin wrapper samples and a letterbook of company official William du Pont (1855-1928) dating from 1886 to 1896. Other scrapbooks (1856-1918, 16 volumes) contain articles relating to company history, explosives and explosions, smokeless powder, gun club tournaments, and samples of powder keg labels. There is a typescript on the derivation of the DuPont Company's oval logo.

Series IV also includes a number of summary histories, including a history of explosions at the Brandywine Mills (1815-1902) compiled by Francis Gurney du Pont (1850-1904), along with a one-volume record of his experiments with water wheels from 1877 to 1879. There are several volumes of notes on tests, accidents, and other activities at the Carney's Point Plant and notes on smokeless powder by F.G. and P.S. du Pont. The series also contains fragmentary records of several social organizations. These include the Brandywine Club, organized by DuPont Company employees in 1893 and housed in the original Eleutherian Mills mansion, the DuPont Employees Association (1910), and the Brandywine Temperance Society (1831-1839), including minutes and lists of members.