GLOSSARY - Archaeological Chemistry - page 521

tertiarium A lead-tin alloy containing 33% tin , used by the Romans mainly for

tinning .
tesserae Small, usually roughly square pieces of stone or glass , used to make deco-
rative mosaics.
textile Cloth woven from yarns and used for making clothing and other coverings.
texture The distinctive appearance or feel of a solid resulting from the size and
shape of the grains or particles of which it is composed.
thermal capacity See heat capacity .
thermal conductivity

See conductivity .

thermal conductor See conductor .

thermal expansion The expansion in size undergone by most materials when

heated.
thermal expansion coefficient The fractional change in length (linear expansion)
or in volume (volume expansion) of a material when heated, per degree of
temperature.
thermal insulator See insulator .

thermal shock A mechanical stress created within a solid body by a fast change in

temperature .
thermal processing Cyclic thermal operations, such as heating and cooling, to
modify the structure and physical properties , although not the chemical composition ,
of objects made from metals ,

alloys , or glass ; see case hardening , quenching ,

tempering .
thermoluminescence The emission of light by solids heated to rather high temper-
atures, albeit below those at which they become incandescent .
thermoluminescence dating See dating , thermoluminescence .
thermoplastic A material that can be repeatedly softened when heated and hard-
ened when cooled without undergoing chemical changes.
thermoremanent magnetism Magnetism acquired by igneous rocks and burned clay
as they cool below their Curie temperature .
thermotropy The change of color due to changes in temperature .
thickener A substance added to a liquid to increase its viscosity .
thixotropy The property of some viscous solutions or suspension s of solids in liquids,
such as paints and ceramic slips , to become more viscous , that is, less fluid , when
left undisturbed, and less viscous and more fluid when shaken or agitated.
thread A fine string of made from two or more yarns twisted together.
threading A process for making metal filaments by slipping a hot metal wire through
a small hole in a hot bar.
thymine (T) A nitrogenous base , one of the constituents of DNA .
timber See lumber .
tin disease See beta tin .