Incorporated in 1912, Atlas Powder Company functioned as an independent explosives and chemicals company until 1971, when it was purchased by Imperial Chemical Industries Limited (U.K.) and became its American affiliate under the name ICI Americas, Inc. The collection consists of minutes, reports, and correspondence from Atlas in addition to both predecessor and subsidiary companies.

Keystone Mushroom Farms, Inc. was a producer, canner, and distributer of mushrooms in Coatesville, Chester County, Pennsylvania. It was the successor of two previous businesses, L.F. Lambert Spawn Co. and Keystone Mushroom Company, Inc., which were formed in the early 1920s with complementary functions of spawn research; production and sales; and mushroom propagation, canning, and distribution. These records document the L.F. Lambert Spawn Co. and the Keystone Mushroom Company, Inc. The collection includes financial records, correspondence, payroll, reports, and shipment and inventory information. Of special interest are the records documenting Lambert's work with the War Production Board to produce penicillin.