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…

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 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 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…

View of a combination hot plate and shaker used to investigate potash at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Potash salts are an important component in the…

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 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…

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…

Equipment used to treat raw materials for the production of fertilizer with nitrogen oxides at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen…

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…

General view of the gas purification rack, a component of an apparatus used to study the catalytic decomposition of ozone at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington,…

General view of apparatus use to determine total and partial vapor pressures at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The apparatus was commonly used to…

General view of the hydraulic pump used to perform steel corrosion tests 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 a laboratory facility and apparatus used to investigate the chemical activity evident in glow discharge at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington,…

General view of an apparatus used to investigate the thermionic emission of positive ions from platinum films sputtered on glass at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

Close-up view of a lime glass tube, part of an apparatus used to investigate the thermionic emission from platinum films sputtered on glass at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory…

View of the front 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 mercury arc…

General view of Mr. Olmstead. operating an ultrasonic oscillator used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Visible components of the oscillator include…

General view of the organic combustion furnace and train utilized 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.)…

Two views of the component parts of an apparatus used to grow higher plants in a sterile medium at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen…

Two views of the liquid ammonia and carbon dioxide pumps and coolers at the Fixed Nitrogen Research Laboratory's Urea Plant. In the production of fertilizer, liquid carbon dioxide and liquid ammonia are commonly…

Close-up view of a sterile culture of small phanerogams, also known as spermatophytes or seed plants, at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The…

Two views of a thermocouple apparatus and assorted components, including a micro-spot welder and soldiering pencil, at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. …

Close-up view of the thermostat used to maintain ammonia bubbles at sixty-five degrees Celsius during steel corrosion tests at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

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…