pycnometers

[MEK104 at psuvm.psu.edu]

      dangold1 at iastate.edu (Daniel M Goldman)  requests info in article

            <dangold1.718579257 at pv1414.vincent.iastate.edu>

>Pycnometers are devices which allow precise determinations of
>volume.
>Does anyone have any knowledge or experience with these?
>There are liquid displacement type instruments and air/gas
> comparison types.
>Any comments or leads appreciated. Thanks. -DmG


A colleague of mine devised a way of measuring the volume of leaves.  A beaker
of distilled water on an analytical balance - immerse the leaf suspended by a
thin wire supported from a ring stand.  If the leaf does not touch the beaker,
the volume of the leaf will be equal to the mass of water displaced (allowing
for minute corrections due to temperature related changes in the mass
density of water).

Sources of error include air bubles which may adhere to the leaf surface, and
variation in how much of the supporting wire is immersed with each measurement.
The later can be minimised by using a very thin wire, the former must be
controlled by observation and pre-wetting of the leaf surface.


MEK