The Offense Section and the Midland Section were concerned with the manufacture of mustard gas. This work was greatly delayed because of the unsatisfactory nature of the so-called chlorohydrin process. Another difficulty was the development of a satisfactory ethylene furnace. Finally in February, 1918, Pope in England discovered the sulfur chloride method of making mustard gas. At once all the energies of the Research Division were concentrated on this process, and in March steps were taken to put this process into production. An experimental plant was established at Cleveland; no attempt was made to manufacture mustard gas on a large scale, but the results obtained in the experimental studies were immediately transmitted to the manufacturing plants at Edgewood Arsenal, the Hastings-on-Hudson plant, the National Aniline & Chemical Company (Buffalo) plant, and the Dow Chemical Company (Midland) plant. The details of the work on mustard gas will be given in a later chapter. Special investigations were undertaken to develop a booster casing and adapter for 75 mm. gas shell, and to duplicate the French process of lining gas shell with glass. The organization of the Development Division at the signing of the Armistice was as follows: Colonel F. M. Dorsey Chief of the Division Major L. J. Willien Supt., Offense Section Capt. O. L. Barnebey Supt., Defense Section Lt. Col. W. G. Wilcox Supt., Experimental Station Capt. Duncan MacRae Special Investigation Section Dr. A. W. Smith Midland Section Capt. J. R. Duff Administrative Section PROVING DIVISION The Proving Division had its origin in the decision to build an Experimental Ground for gas warfare under the direction of the Trench Warfare Section of the Ordnance Department. While this decision was reached about September, 1917, actual work on the final location (Lakehurst, N. J.) was not started until March 26, 1918, and the construction work was not completed until August 1, 1918. However, firing trials were started on April 25, 1918, and in all 82 were carried out. The Proving Division was created to do two things: To experiment with gas shell before they reached the point where they could be manufactured safely in large numbers for shipment overseas; and to prove gas shell, presumably perfect and ready for shipment, to guard against any mechanical inaccuracies in manufacture or filling. It is evident that the second proposition is dependent upon the first. Shell can not be proved to ascertain the effect of gases under various conditions and concentrations until the mechanical details of the shell itself, purely an Ordnance matter, have been standardized. Unfortunately many of the tests carried out had to do with this very question of testing Ordnance.