General view of an experimental apparatus to test the production of hydrogen from methane and steam at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C.

The Fixed…

General view of Dr. R.O.E. Davis demonstrating use of an apparatus for filling tubes in order to study ammonia-carbon dioxide-Urea-water systems at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory…

General view of C.A. Black demonstrating use of an apparatus for filling tubes in order to study ammonia-carbon dioxide-Urea-water systems at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory…

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…

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…

R.A. Nelson (left) and E.S. Lamar (right) demonstrating an apparatus used to study the decomposition of ammonia on hot catalyst surfaces by means of the coated strip method. This apparatus was used at the U.S.…

Close-up view of an apparatus used to study the decomposition of ammonia on hot catalyst surfaces by means of the coated strip method. This apparatus was used at the U.S. Department of Agriculture's Fixed Nitrogen…

General view 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…

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…

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…

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 Brown Potentiometer and other assorted apparatus and machinery used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Potentiometers are used to…

High-temperature vacuum furnace used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory.

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

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…

Exhibition display concerning the fixation of atmospheric nitrogen at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The display includes several diagrams depicting…

U.S. Department of Agriculture exhibition display concerning fertilizer values as determined by per cent of plant food. The display includes several photographs of a range of agricultural crops, including wheat, cotton,…

Electric arc furnace used to make ferro-aluminum alloys at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory.

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

Apparatus used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory to study the separation of ammonia from carbon dioxide.

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

General view of the exterior of the water gas generator at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The term "water gas" commonly refers to the mixture of…

General view of W.E. Kuentzel demonstrating use of an apparatus for the removal of carbon monoxide from water gas by means of preferential combustion at the U.S. Department of Agriculture's Fixed Nitrogen Research…

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…

R.A. Nelson (left) and Dr. C.H. Kunsman (right) demonstrating an apparatus used to study the decomposition of ammonia on catalyst surfaces at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory…

M.C. Molstad demonstrating use of an apparatus for the removal of carbon dioxide from water gas by means of scrubbing under pressure at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

General view of R.J. Connor photographing the spectrum of active nitrogen at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. In chemistry, "spectrum" commonly refers…

General view of Mrs. M.K. Murray demonstrating use of a nitrometer, an apparatus used to determine the amount of nitrogen or nitrogen compounds in a substance or mixture, at the U.S. Department of Agriculture's Fixed…