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potassium nitrate

(Encyclopedia)potassium nitrate, chemical compound, KNO3, occurring as colorless, prismatic crystals or as a white powder; it is found pure in nature as the mineral saltpeter, or niter. (The name saltpeter is also ...

Todd, Sir Alexander Robertus

(Encyclopedia)Todd, Sir Alexander Robertus, 1907–97, Scottish biochemist, Ph.D., Univ. of Frankfurt am Main, 1931; Oxford, 1933. Todd held posts at Edinburgh Univ. (1934–36), the Lister Institute of Preventive ...

solder

(Encyclopedia)solder sŏdˈər [key], metal alloy used in the molten state as a metallic binder. The type of solder to be used is determined by the metals to be united. Soft solders are commonly composed of lead an...

silver nitrate

(Encyclopedia)silver nitrate nīˈtrāt [key], chemical compound, AgNO3, a colorless crystalline material that is very soluble in water. The most important compound of silver, it is used in the preparation of silve...

Stein, William Howard

(Encyclopedia)Stein, William Howard, 1911–80, American biochemist, b. New York City, Ph.D. Columbia, 1937. Stein was a professor at the Rockefeller Institute for Medical Research (now Rockefeller Univ.) from 1937...

nitrogen

(Encyclopedia)nitrogen nīˈtrəjən [key], gaseous chemical element; symbol N; at. no. 7; interval in which at. wt. ranges 14.00643–14.00728; m.p. −209.86℃; b.p. −195.8℃; density 1.25 grams per liter at ...

soil

(Encyclopedia)soil, surface layer of the earth, composed of fine rock material disintegrated by geological processes; and humus, the organic remains of decomposed vegetation. In agriculture, soil is the medium that...

leaching

(Encyclopedia)leaching, method of extraction in which a solvent is passed through a mixture to remove some desired substance from it. A simple example is the passage of boiling water through ground coffee to dissol...

Metchnikoff, Élie

(Encyclopedia)Metchnikoff, Élie ālēˈ mĕchˈnĭkôf [key], 1845–1916, Russian biologist. He studied in Russia and Germany, lectured at the Univ. of Odessa, and, after working with Pasteur in Paris, became (19...

medlar

(Encyclopedia)medlar mĕdˈlər [key], small deciduous tree (Mespilus germanica) of the family Rosaceae (rose family), native to Europe and Asia. It has luxuriant foliage and large white or pinkish flowers; in the ...