Exterior view of a chemical warfare research laboratory under construction at American University near Washington, D.C. American research concerning chemical warfare was initially organized under the Bureau of Mines,…

General view of a large-capacity constant temperature bath with a removable glass front used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen…

General view of an apparatus used to determine the solubility of gases in liquids at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Visible in the bath of the…

General view of a table-top model of a synthetic ammonia plant showing an assortment of plant machinery and apparatus. The model was created by the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory…

General view of E.J. Fox demonstrating use of towers to facilitate the absorption of nitric oxides by phosphate rock at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.…

General view of E.J. Fox demonstrating use of a rotary tunnel to facilitate the absorption of nitric oxides by ground phosphate rock at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

General view of the thermostat and apparatusused to measure vapor pressures in the study of Urea synthesis at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Urea is a…

General view of the thermostat, apparatus, and analytical train used to measure vapor pressures in the study of Urea synthesis at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

General view of an apparatus used to oxidize ammonia at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen Research Laboratory (F.N.R.L.) was…

General view of an experimental apparatus to test the production of hydrogen from methane and steam at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed…

General view of the ammonia-carbon dioxide pump and Urea autoclave used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen Research Laboratory…

General view of an autoclave and still at the Fixed Nitrogen Research Laboratory's Urea Plant. Urea is a water-soluble powder form of carbonic acid frequently used as a fertilizer and feed supplement.

The Fixed…

General view of W.E. Kuentzel demonstrating use of an apparatus for the removal of carbon monoxide from water gas by means of preferential combustion at the U.S. Department of Agriculture's Fixed Nitrogen Research…

General view of V.L. Gaddy demonstrating an apparatus used to create a constant-temperature bath to determine the equilibrium of Urea, a water-soluble powder form of carbonic acid frequently used as a fertilizer and…

General view of a carbon dioxide drier, compressor, liquifier, and liquid storage used at the Fixed Nitrogen Research Laboratory's Urea Plant. Urea is a water-soluble powder form of carbonic acid frequently used as a…