Alan <Arutner@AOL.COM> wrote:
> res0bidc@VERIZON.NET writes:
> > Is distilled water an insulator?
>
> This OT topic piqued my interest and so I dug up my copy of "Handbook of
> Chemistry and Physics" 40th edition 1959 pp 3456; published by Chemical
> Rubber Publishing Co. price December 1960 US$ 5.75 (!!)"
>
>        Dialectic constant of water:  88.00 at 0 degree C     55.33 at 100
> degree C
>
>         Resistance in ohms per centimeter cubed:
>                           Distilled water at 18 degree C   =  0.5 x 10^6
>                            Petroleum at ? degree C         =  2 x 10 ^16

Better get a new handbook! Volumetric resistivity has units of ohm-cm, not
ohm/cm^3. This paper gives some relevant data:

  http://www.purite.co.uk/technical/CHARACTERISTICS_OF_DEIONISED_WATER.pdf

"Ultra-pure" water falls in the range 10-18  Mohm-cm
"Pure" water falls in the range        1-5   Mohm-cm
"Purified" water falls in the range   20-500 kohm-cm

Apparently, the theoretical maximum resistivity at 25C is 18.3 Mohm-cm,
which means that a 1-cm cube of water would measure 18.3 Mohm across
opposite faces. Whether this qualifies as an insulator depends on the
application, I guess.

Resistivity goes higher at lower temperatures. I guess pure ice really
is an insulator.

-- Dave Tweed

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