Apparatus used to analyze vapors emitted from the reaction of liquid carbon dioxide and liquid ammonia at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. In the production of fertilizer, liquid carbon dioxide and liquid ammonia are commonly combined under high-pressure to produce Urea, a water-soluble powder form of carbonic acid frequently used as a fertilizer and feed supplement. The apparatus in this photograph was specifically used to measure carbon, hydrogen, and nitrogen present in the vapor.

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.