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Re: Pycnometer



At 10:03 6/26/97 -0500, Jerry Lisantti wrote:


A colleague would like to purchase a pycnometer for accurately measuring
the density of a liquid in situ. Can someone please give me some
information about these devices and where to possibly purchase them.

Jerry Lisantti


1) Information.

The Greek word pyknos (dense) is rendered with a k in European usage,
and with a c in US usage. There are various forms of pycnometer.
One common arrangement has a glass u tube - of which one leg is of larger
diameter - and both ends of which admit to being heat sealed before
weighing then breaking under the surface of some absorbant liquid.
This sort is adapted to the measurement of the solubility of highly
soluble gases in solution. (ref 1, 2)

A second kind is a metal flask fitted with two needle valves and a pressure
gage. This is suited to measuring the specific gravity of liquified gas
at up to 2000 psi (Ref 3)

Particularly in US usage, a pycnometer takes the form of a flask of known
volume, as defined by a graticule in the stoppered neck, or by the complete
volume of flask with fitted stopper having a central axial hole, or having
a stopper with a longitudinal notch for the same purpose.
This container may also hold a closely fitted thermometer (ref 4 and 6)

These flasks with thermometers are also suited to measuring the
expansivities of liquids. (ref 5 and 7)

1 - Physical Chemistry Wood & Holliday, Butterworths (1967)
2 - Nicol Pyknometer, Griffin & George catalog
3 - SETA Pyknometer, ibid
4 - New Century Dictionary, Appleton, Century, Crofts. (1957)
5 - Dictionary of Science, Uvarov & Isaacs, Penguin (1993)
6 - Fisher Scientific Catalog (1981) illustrates not only a
variety of volumetric flasks but also a light alloy device
in three parts which might also serve as a tablet press.
It is intended for compacting highly viscous and semi-solid
materials.
7 - American Scientific Products (catalog)


2) Sources of Supply. Various Scientific equipment catalogs will
illustrate this device. Some of them are mentioned above.

Regards
brian whatcott <inet@intellisys.net>
Altus OK