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carbon

(Encyclopedia)CE5 The three solid forms of pure carbon: In the diamond crystal each carbon atom is surrounded symmetrically by four other carbons (at each of the four corners of a tetrahedron). In the graphite c...

combustion

(Encyclopedia)combustion, rapid chemical reaction of two or more substances with a characteristic liberation of heat and light; it is commonly called burning. The burning of a fuel (e.g., wood, coal, oil, or natura...

nitrate

(Encyclopedia)nitrate, chemical compound containing the nitrate (NO3) radical. Nitrates are salts or esters of nitric acid, HNO3, formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radic...

radioimmunoassay

(Encyclopedia)radioimmunoassay (RIA), highly sensitive laboratory technique used to measure minute amounts of substances including antigens, hormones, and drugs present in the body. The substance or antigen (a fore...

lipids

(Encyclopedia)lipids, a broad class of organic products found in living systems. Most are insoluble in water but soluble in nonpolar solvents. The definition excludes the mineral oils and other petroleum products o...

density

(Encyclopedia)density, ratio of the mass of a substance to its volume, expressed, for example, in units of grams per cubic centimeter or pounds per cubic foot. The density of a pure substance varies little from sam...

Beer's law

(Encyclopedia)Beer's law [for August Beer], physical law stating that the quantity of light absorbed by a substance dissolved in a nonabsorbing solvent is directly proportional to the concentration of the substance...

cleavage

(Encyclopedia)cleavage, tendency of many minerals to split along definite smooth planar surfaces determined by their crystal structure. The directions of these surfaces are related to weaknesses in the atomic struc...

Young's modulus

(Encyclopedia)Young's modulus [for Thomas Young], number representing (in pounds per square inch or dynes per square centimeter) the ratio of stress to strain for a wire or bar of a given substance. According to Ho...

prospecting

(Encyclopedia)prospecting, search for mineral deposits suitable for mining. Modern prospecting has replaced earlier methods based on chance or superstition (e.g., use of the divining rod) with others based on a sci...