Columbia Encyclopedia

Search results

500 results found

cyanide process

(Encyclopedia)cyanide process or cyanidation, method for extracting gold from its ore. The ore is first finely ground and may be concentrated by flotation; if it contains certain impurities, it may be roasted. It i...

pyrimidine

(Encyclopedia)CE5 Pyrimidines found in deoxyribonucleic acid (DNA) pyrimidine pīrĭmˈĭdēnˌ [key], type of organic base found in certain coenzymes and in the nucleic acids of plant and animal tissue. The th...

ammonium group

(Encyclopedia)ammonium group, in chemistry, a positively charged nitrogen atom joined by single bonds to four other atoms or groups. The simplest ammonium group, NH4+, is formed by protonation of ammonia, NH3, e.g....

hydrogenation

(Encyclopedia)hydrogenation hīdrôjˈənāˌshən, hīˌdrəjənāˈshən [key], chemical reaction of a substance with molecular hydrogen, usually in the presence of a catalyst. A common hydrogenation is the harde...

ibuprofen

(Encyclopedia)ibuprofen īˈbyo͞oprōˌfən [key], nonsteroidal anti-inflammatory drug (NSAID) that reduces pain, fever, and inflammation. Along with naproxen and ketoprofen, ibuprofen belongs to the propionic aci...

drypoint

(Encyclopedia)drypoint, an intaglio printing process in which the lines are scratched directly into a metal plate with a needle; also, the print made from such a plate. Although it is often used in combination with...

tamarind

(Encyclopedia)tamarind tămˈərĭnd [key], tropical ornamental evergreen tree (Tamarindus indica) of the family Leguminosae (pulse family), native to Africa and probably to Asia, but now widely grown in the tropic...

bromide

(Encyclopedia)bromide, any of a group of compounds that contain bromine and a more electropositive element or radical. Bromides are formed by the reaction of bromine or a bromide with another substance; they are wi...

adenosine monophosphate

(Encyclopedia)adenosine monophosphate (AMP) ədĕnˈəsēn mŏnˌəfŏsˈfāt [key], organic compound composed of an adenine base, the sugar ribose, and one phosphate unit. AMP is one of the possible products of th...

Cannizzaro, Stanislao

(Encyclopedia)Cannizzaro, Stanislao stänēsläˈō kän-nēt-tsäˈrō [key], 1826–1910, Italian chemist. From 1861 he was professor at Palermo and from 1871 at Rome, where he was also a member of the senate and...