General view of an apparatus used to analyze micro quantities of gases 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 apparatus used for the emission of positive ions at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The individuals present in the photograph are…

Close-up view of an apparatus used to produce soft x-radiation 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 an apparatus for the study of equilibrium in the iron-water-iron oxide-hydrogen system at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed…

General view of the thermostat and assorted apparatus used to study the compressibility of gases at high pressures at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. …

General view of an apparatus used to analyze hydrogen at the Fixed Nitrogen Research Laboratory's Synthetic Ammonia Division.

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

General view of the construction and calibration of an apparatus used to analyze the decomposition of ammonia on hot surfaces at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

General view of an apparatus used to grow plants under sterile conditions at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen Research Laboratory…

Close-up view of the assembly of an apparatus used for sterile cultures of taller green plants at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen…

Two views of assorted apparatus 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 individuals present…

General view of assorted apparatus used in the Steel Corrosion Laboratory at the U.S. Department of Agriculture's Fixed Nitrogen Research facility located in Washington, D.C. Apparatus include a constant volume…

Mr. Hetherington demonstrating the barometers and potentiometer used for temperature control at the High-Pressure Laboratory, part of the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory facilities…

General view of the Bone and Wheeler gas analysis apparatus used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. A Bone and Wheeler apparatus, which reads gas…

General view of two compression and high-pressure storage cylinders used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Part of a hand-operated booster connected…

General view of compressor used in the carbon dioxide refrigeration system at the Fixed Nitrogen Research Laboratory's High-Pressure Laboratory. The individual present in the photograph is identified as Mr. Tremearne.
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Close-up view of a decomposition chamber used to facilitate the thermal decomposition of ammonia on tungsten, molybdenum, nickel, and iron catalysts at the U.S. Department of Agriculture's Fixed Nitrogen Research…

General view of the microapparatus and assorted laboratory equipment used to study bacterial nitrogen fixation at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.…

Two views of device used to study positive ions, presumably in the activation of nitrogen gas and hydrogen, at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The…

General view of Dr. D.C. Bardwell using an apparatus to experiment with the chemical effects of radon at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed…

Two views of Dr. Kuentzel studying the thermal and catalytic decomposition of azomethane at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen…

General view of Dr. Leatherman using an apparatus to determine the amount of inert gas present in nitrogen made from the fractionation of liquid air at the Fixed Nitrogen Research Laboratory's High-Pressure Laboratory. …

General view of Dr. Leatherman using an apparatus to measure traces of inert gas and air in nitrogen at the Fixed Nitrogen Research Laboratory's High-Pressure Laboratory.

The Fixed Nitrogen Research Laboratory…

Close-up view of the driving mechanism of an automatic self-recording infrared spectrograph used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Features of note…

General view of an unidentified employee operating an apparatus used to produce x-radiation in order to study nitrogen fixation catalysts at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory…

Front lateral view of an infrared spectrograph used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Visible components of the spectrograph include the thermocouple…