Pycnometer
Century Dictionary and Cyclopedia

 n pycnometer An instrument for determining the relative density or specific gravity of solid bodies; a specificgravity flask. It consists of a glass flask with a long tubular stopper. The flask, when filled with distilled water, and when the stopper is pressed in till the water overflows through the tubule of the stopper, will at any given temperature hold a specific volume and therefore a specific weight of the liquid. The combined weight of the flask and its stopper, and the weight of water it contains when the stopper is pressed in, having been ascertained, and also the total weight of the flask and its contents after the solid body has been placed in it, the then unfilled space refilled with distilled water, and the stopper again pressed in, the weight of the solid body in air and the weight of the water displaced by it when it is put in the pycnometer can be easily determined. These are the data necessary to compute the relative density or specific gravity of the body — a unit of mass of distilled water at 4° C. divided by its apparent volume at the same temperature being the usual unit of density. This unit is written “1.000” in specificgravity tables in which the specific gravity of bodies lighter than water is expressed in three places of decimals. See density, densimeter, specific gravity (under gravity), volume, and mass.
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Chambers's Twentieth Century Dictionary

 n Pycnometer piknom′etėr an instrument for determining the specific gravity of solid bodies.
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Webster's Revised Unabridged Dictionary
Gr. dense, compact + meter,
Chambers's Twentieth Century Dictionary
Gr. pyknos, thick, metron, measure.
In news:
AccuPyc II 1340 pycnometers from Micromeritics Instrument Corp. Are fast, fully automatic analyzers that provide highspeed, highprecision volume measurements and density calculations on a wide variety of powders, solids and slurries.
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