Two views of Dr. E.D. Crittenden with an apparatus used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory to test catalysts at 1 to 100 atmospheres of pressure. Key components of the apparatus are visible in the photographs, including the reaction bombs, automatic pressure regulating valve, and gauge, as well as gas sampling and measuring devices.

The Fixed Nitrogen Research Laboratory (F.N.R.L.) was established at American University in 1919 under the directorship of Arthur B. Lamb. Initially part of the War Department, the F.N.R.L. was the successor to several wartime initiatives to develop a secure domestic supply of nitrate compounds necessary for the manufacture of explosives during World War I. With a staff of about 110 individuals, including 35 to 50 chemists, the F.N.R.L. focused on the manufacture, production, and development of products of atmospheric nitrogen, including munitions and fertilizers.