The easiest thing I can think of would be for you to buy a gallon of
distilled water, mark the fill level. Dump it into the carboy in
question. Fill the water jug up to there again and repeat, marking
each time on the carboy. You will be pretty close doing it this way.
If it does not fill it up, use something else to figure out the
difference, you have the bulk of the measurement already.

Could you use the milk jug idea? Sure, but all of this assumes that
the injection mold that made it was perfect (and it probably was not)
and the jug does not change with temperature. None of that is
correct; of course it changes, everything does. The water jug was made
in the same machine, but if you are looking for e precision of a few
ounces, you should be OK.

Now the right way to do this is:

If you have precise scale or load cell that can measure 50 to 60
pounds with a few hundredths of precision:

A gallon of water= 3785.5 ml

(5) 750 ml bottles of wine = 3750 ml, it's within 1%.

Pure water (free from air) weighs:

999.13 gm/L @ 15C or 8.337 lbs/gal (US)
998.23 gm/L @ 20C or 8.330 lbs/gAL (US)
997.07 gm/L @ 25C OR 8.320 lbs/gal (US)

If you want to get really precise, use distilled water for all of this
and measure the temperature of the water and carboys, or leave them in
the same place for a day to stabilize.

Class A graduated cylinders are made of borosilicate glass and have a
known predictatble coefficient of thermal expansion. They can be used
as primary standards for volume. That is actually the correct way to
do this. It may be equvalent to killing a fly with a nuclear weapon
though... )
Regards,
Joe




(Dr. Richard E. Hawkins) wrote in message >...
> In article >,
> A. J. Rawls > wrote:
> >On Sat, 19 Jun 2004 15:03:25 +0000 (UTC),
> >(Dr. Richard E. Hawkins) wrote:
>
> >>Argh. I've *got* to find a way to calibrate my carboys to figure out
> >>exactly where 5 & 6 gallons are (particularly 6).
>