General view of a colorimeter used to analyze nitrogen dioxide at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. With regards to chemistry, colorimeters are used to…

General view of a high-pressure pump used 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 established at…

General view of the electron inertia apparatus used 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 a conference room 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 established at American…

General view of the compressors used at the Fixed Nitrogen Research Laboratory's catalyst testing plant.

The Fixed Nitrogen Research Laboratory (F.N.R.L.) was established at American University in 1919 under the…

General view of the library 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 established at American…

General view of the auxiliary gasoline engine used at the Fixed Nitrogen Research Laboratory's catalyst testing plant. The insignia of the General Motors Company is visible at the base of the engine.

The Fixed Nitrogen…

General view of an apparatus used to remove 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 apparatus used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory to test catalysts under one atmosphere of pressure.

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

General view of an apparatus used to study absorbents for a high-pressure ammonia system 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 study liquid absorbents for ammonia 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 acetylene welding at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The man visible in the photograph is identified as J.J. Connor. This photograph is…

General view of the electrical shop at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory showing assorted machinery and apparatus. The man visible on the left-hand side of the photograph is…

General view of F.F. Robey at work in the carpenter shop at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory showing assorted machinery and apparatus.

The Fixed Nitrogen Research Laboratory…

General view of electrolytic cells used for the production of hydrogen 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 the repair shop at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory showing assorted machinery and apparatus.

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

General view of the control board for the catalyst testing system 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.)…

General view of apparatus used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory for the reaction of active nitrogen with carbon monoxide, carbon dioxide, and oxygen and hydrogen gas.

The Fixed…

General view of the apparatus used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory to introduce silica gel into an arc process. In the early 20th century, the arc process, in which electric…

General view of reaction bombs used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory to test catalysts at 100 atmospheres of pressure. Numbers are visible on the exterior of the various…

General view of crackers, deoxidizers, and scrubbers at the Fixed Nitrogen Research Laboratory's catalyst testing plant. Numbers are visible on the exterior of the various containers.

The Fixed Nitrogen Research…

General view of high-pressure purification apparatus used at the Fixed Nitrogen Research Laboratory's catalyst testing plant.

The Fixed Nitrogen Research Laboratory (F.N.R.L.) was established at American University in…

General view of the exterior of the gas storage facility at the Fixed Nitrogen Research Laboratory's catalyst testing plant. Two unidentified workers are visible on the right-hand side of the photograph. A sign reading…

Apparatus for the production of catalysts used to initiate water-gas shift reactions at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The water-gas shift reaction…

View of a stirring machine designed at the Arlington Experimental Farm in Arlington, Virginia. Established by an act of Congress in April 1900, Arlington Farm served as the main field laboratory for the Bureau of Soils,…