General view of a phosphoric acid furnace in use at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Phosphorus fumes and molten slag are seen emerging from the furnace…

General view of a phosphoric acid furnace in use at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Phosphorus fumes are seen emerging from the furnace as part of the…

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…

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…

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 reaction bombs used at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory to test catalysts at 100 atmospheres of pressure. Numbers are visible on the exterior of the various…

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…

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 numbered test tube samples from the Ammonia-(Urea-Water) system at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Urea is a water-soluble powder form…

Four stoppered jars containing samples of commercial fertilizer and concentrated fertilizer mixtures produced at the Arlington Experimental Farm in Arlington, Virginia. Established by an act of Congress in April 1900,…

View of a shaking machine designed at the Arlington Experimental Farm in Arlington, Virginia. Established by an act of Congress in April 1900, Arlington Farm served as the main field laboratory for the Bureau of Soils,…

General view of an apparatus used to facilitate the adsorption of silica gel and nitrogen oxide at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Adsorption refers to…

View of a stirring machine designed at the Arlington Experimental Farm in Arlington, Virginia. Established by an act of Congress in April 1900, Arlington Farm served as the main field laboratory for the Bureau of Soils,…

General view of storage piles of raw material, including greensand, leucite, coke, and limestone, used in the experimental blast furnace at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located…

General view of an apparatus used to study the Bucher Process for the fixation of nitrogen at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Based on research…

General view of an apparatus used to study the thermal dissociation of sodium cyanide at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Thermal dissociation is…

General view of the thermostat and apparatusused to measure vapor pressures in the study of Urea synthesis at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. Urea is a…

General view of a thermostat apparatus used to measure rates of reaction 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 thermostat, apparatus, and analytical train used to measure vapor pressures in the study of Urea synthesis 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…

General view of Travis P. Hignett (left) and Mr. Royster (right) reading the temperature inside the experimental blast furnace at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

General view of the hot blast stove, a component of the phosphoric acid furnace at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. The individuals visible in the…

Close-up view of Travis P. Hignett using an optical pyrometer to measure the combustion temperature of coke in the blast furnace at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in…

General view of Travis P. Hignett demonstrating use of the blowing engines for the experimental blast furnace at the U.S. Department of Agriculture's Fixed Nitrogen Research Laboratory located in Washington, D.C. A…

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…