glass |
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. |
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cover glass, a thin glass plate
used to cover an object for microscopic examination. Written
also coverglass. |
crown glass, a glass of low
refractive index (achieved by incorporating a considerable
percentage of phosphorus pentoxide); used in combination with
flint glass in multielement lenses. |
cupping glass, a small vessel
from which the air has been or can be exhausted, applied to the
body in the practice of cupping (q.v.). |
flint glass, a highly refractive glass in
which calcium has been replaced in large part by lead; used for
lenses and prisms and in the manufacture of cut glass. |
object glass, see objective. |
optical glass, glass of high quality and
controlled composition, used for lenses. |
quartz glass, pure fused silica,
used for prisms, lenses, and chemical vessels because its index
of thermal expansion is so small that it does not crack when
heated or cooled and because it transmits more ultraviolet
radiation than does ordinary glass. |
test glass, a small glass vessel, resembling
a beaker, used in a chemical laboratory. |
Wood glass, see under filter. |
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