The Chemical Warfare Development Division facilities included a manufacturing building for the development of mustard gas which was located near the entrance of the present Gate No. 2. The mustard gas was produced in building 20A and stored in Building 30 until it was shipped from the plant.

The Chemical Warfare Development Division mustard gas plant, Building 20A, was one of the first manufacturing buildings on the site and was built around the turn of the century. The plant manufactured chloroform prior to the U.S. Army contracting Dow to make mustard gas during World War I. This Dow facility was the first in the United States to make synthetic chloroform. Since chloroform uses a chlorhydrinate process in its manufacture, the equipment was readily converted to the production of mustard gas, which requires the same process.

The purpose of the Chemical Warfare Development Division at Midland, Michigan, was to develop a process for the large scale production of mustard gas. Experimental production of a thousand tons of mustard gas was completed prior to the shutdown of the plant at the end of the war. Following the war, the plant was converted and usad for the production of aspirin.

Mustard agent and contaminated equipment from the Chemical Warfare Development Division was disposed of on Dow Chemical property by burial.