- cover g. a thin g. disk or plate covering an object examined under the microscope. SYN: coverslip.
- crown g. a compound of lime, potash, alumina, and silica; commonly used in lenses; has a low dispersion (52.2) relative to index of refraction (1.523).
- cupping g. a g. vessel, from which the air has been exhausted by heat or a special suction apparatus, formerly applied to the skin in order to draw blood to the surface. SEE ALSO: cupping, cup. SYN: cup (2).
- flint g. g. that contains lead oxide instead of lime to increase index of refraction; used in reading segments of fused bifocal lenses.
- quartz g. a transparent, colorless crystal, made by fusing pure quartz sand, which transmits ultraviolet light.
- soluble g. a silicate of potassium or sodium, soluble in hot water but solid at ordinary temperatures; used for fixed dressings. SYN: water g..
- vita g. a specially prepared g. that is transparent to ultraviolet rays of the spectrum.
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glass 'glas n, often attrib
1 a) an amorphous inorganic usu. transparent or translucent substance consisting of a mixture of silicates or sometimes borates or phosphates formed by fusion of silica or of oxides of boron or phosphorus with a flux and a stabilizer into a mass that cools to a rigid condition without crystallization
b) a substance resembling glass esp. in hardness and transparency <organic \glasses made from plastics>
2 a) an optical instrument or device that has one or more lenses and is designed to aid in the viewing of objects not readily seen
b) glasses pl a device used to correct defects of vision or to protect the eyes that consists typically of a pair of glass or plastic lenses and the frame by which they are held in place called also eyeglasses
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(glas) [L. vitrum] 1. a hard, brittle, and often transparent material, usually consisting of the fused amorphous silicates of potassium or sodium, and of calcium, with silica in excess. 2. a container, usually cylindrical, made from glass.Medical dictionary. 2011.