GLOSSARY - Archaeological Chemistry - page 507

from volcanogenic materials, were used in antiquity, particularly by the Romans,
to prepare hydraulic cement .
ppb Acronym for parts per billion .
ppm Acronym for parts per million .
precious metal See metal, precious .
precious stone See gemstone .
precipitate A solid that separates, as extremely small particles , out of a liquid solution .
precipitation Formation of a precipitate as a result of either a chemical reaction or
the evaporation of water.
primary clay See clay, primary .
primary mineral See mineral, primary .
primordial element See element, primordial .
primordial isotope See isotope, primordial .
properties, chemical See chemical properties .
properties, physical See physical properties .
protein One of a large group of complex organic compounds that consist of many
amino acids joined together by peptide bonds ; they are essential to all living organ-
isms, making up the main component of the cell s protoplasm .
protein fiber See fiber, protein.
proton A subatomic particle in the nuclei of atoms that has the same mass as the elec-
tron but with a positive electric charge.
protoplasm The entire contents of a cell , including the nucleus ; see cytoplasm .
provenance The geologic or geographic source of a material or object.
provenience See provenance .
PSD Acronym for particle size distribution .
puering The removal of residual dehairing chemicals from treated animal skin; an
ancient puering process entails immersing the skins in an infusion of fermenting
dog manure and results in supple, stretchy, and soft skins, softer than those
obtained by bating ; see drenching .
pulled wool See wool, pulled .
pumice A light-colored, frothy volcanic rock , formed by the expansion of gas in
solidifying molten lava .
putrefaction The decomposition, also known as rot , of organic matter , particularly
proteins , which is accompanied by the evolution of foul-smelling compounds, such
as mercaptanes and ammonia.
pyrolusite A mineral composed of manganese oxide, used as a black pigment and
as glassmaker's soap .
pyrolysis A process of chemical decomposition brought about by heat.
pyrometallurgy The use of fire and heat to extract and recover metals from ores .
qualitative analysis See analysis, qualitative .