Two views of Dr. F.E. Allison studying the fixation of nitrogen by bacteria at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen Research Laboratory…

Two views of an apparatus used to oxidize ammonia with pure oxygen using bed catalysts at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The individual visible in the…

Two views of the construction of the phosphoric acid furnace at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. This furnace was used to make phosphoric acid through…

Assorted views of slag being tapped from the experimental blast furnace at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The individuals visible in the photographs…

Two views of the exterior of the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory facility located at American University near Washington, D.C. The Fixed Nitrogen Research Laboratory (F.N.R.L.) was…

Two views 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 established…

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…

Two views of Mr. C.A. Black with an apparatus used to measure the solubility of methane in hydrocarbons under high pressures at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

Two views of J.E. Reuter at work in the instrument shop at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory showing assorted machinery and tools.

The Fixed Nitrogen Research Laboratory…

Two views of J.E. Reuter at work in the instrument shop at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory showing assorted machinery and tools.

The Fixed Nitrogen Research Laboratory…

Two views of an apparatus used to determine the hygroscopicity of fertilizer materials and mixtures at the the Arlington Experimental Farm in Arlington, Virginia. The individual visible in the first photograph is…

Two views of a thermostated agitating device with an all-glass system used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The term "thermostated" refers to a…

Three views of the carbon monoxide generator and compressor used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The individual visible in the second and third…

Two views of the U.S. Department of Agriculture's exhibition display at the Chemical Industries Exposition in New York. Highlighting the work of the Fixed Nitrogen Research Laboratory, the display includes panels on…

Two views of an exhibition display concerning the work of the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The display includes assorted sample jars and a photograph…

Two views of the exterior of the Fixed Nitrogen Research Laboratory facilities located at American University near Washington, D.C. The Fixed Nitrogen Research Laboratory (F.N.R.L.) was established at American…

General view of an unidentified apparatus, possibly a hopper or type of granulation equipment, at an unidentified U.S. Department of Agriculture facility, likely the U.S.D.A.'s Agricultural Engineering Laboratory. Three…

Two views of a chemist inserting radioactive materials into an apparatus at an unidentified U.S. Department of Agriculture facility. The U.S.D.A. commonly used radioactive material for a variety of research and testing,…

General view of fertilizer trays on a suspension apparatus at an unidentified U.S. Department of Agriculture facility.

General view of assorted equipment and apparatus in the Constant Humidity Room at the the U.S. Department of Agriculture's Fertilizer Machinery Laboratory located at the Arlington Experimental Farm in Rosslyn…

General view of a drillability apparatus with fertilizer hoppers, a starwheel, and rotating plate mechanism at an unidentified U.S. Department of Agriculture facility.

General view of a chemist handling radioactive material at an unidentified U.S. Department of Agriculture facility. The U.S.D.A. commonly used radioactive material for a variety of research and testing, including the…

General view of chemist George Wieczorek (left) and an unidentified chemist using a Geiger counter to measure ionizing radiation in radioisotopes at an unidentified U.S. Department of Agriculture facility. A box of…

Three views of the Engine Room at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. showing assorted machinery and apparatus.

The Fixed Nitrogen Research Laboratory…

View of chemist George Wieczorek (right) and an unidentified chemist using a Geiger counter to measure ionizing radiation in an unknown substance at a U.S. Department of Agriculture facility. The U.S.D.A. commonly used…