General view of the control panel for compressors at the Fixed Nitrogen Research Laboratory's Urea Plant. In the production of fertilizer, liquid carbon dioxide and liquid ammonia are commonly combined under…

L.A. Pinck demonstrating an apparatus used for the nitration of organic substances at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed Nitrogen Research…

General view of the carbon dioxide regenerator at the Fixed Nitrogen Research Laboratory's Urea Plant. In the production of fertilizer, liquid carbon dioxide and liquid ammonia are commonly combined under high-pressure…

General view of the exterior of the Fixed Nitrogen Research Laboratory's Urea Plant, showing assorted apparatus and equipment used to produce Urea, a water-soluble powder form of carbonic acid frequently used as a…

General view of V.L. Gaddy demonstrating use of compressors at the Fixed Nitrogen Research Laboratory's Urea Plant. In the production of fertilizer, liquid carbon dioxide and liquid ammonia are commonly combined under…

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 a high-pressure circulating 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…

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 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 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 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 Mr. L. Pinck demonstrating use of a liquid air condenser employed for low-temperature distillations at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.
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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…

Rotary filter used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory to extract cyanamide from calcium cyanamide.

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

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 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 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…

Combination of photomicrographic camera and metallurgical microscope.