"Ian Johnston" wrote in message
news:cCUlhtvFIYkV-pn2-slrYLOWSYEIp@localhost...
On Tue, 13 Jan 2004 20:47:07 UTC, (Andy Durbin)
wrote:

: That seems to say that the volume of copper is *very* small so its
: mass would be too. Is there any useful heat exchange between a
: negligible mass of copper and .45 litres of air?

I bet the trick wouldn't work if the glass was really, really full.
You can pile a lot of water up in a meniscus.

That said, the specific heat capacities for copper and air are 380 and
1004 J/kgK, but since the densities are 896 and 1.225 kg/m^3, the
volumetric heat capacities are 340 and 1.23 kJ/Km^3, a ratio of 276:1.
In other words, filling 1% of the capacity with copper will nearly
treble the heat capacity of the, um, capacity.

Ian
--

I've been doing some searching for a 0.45L vacuum flask - no luck. All
consumer thermos bottles these days are heavy, bulky, not very insulating
stainless steel. Laboratory glassware suppliers do sell 500ml glass dewars.
The ones that I could find however, are short, wide mouth containers which,
with the large rubber stopper required, wouldn't be very good either.

Anybody got a lead on a narrow-mouth, half liter glass dewar?

The other approach is to use the tan plastic 0.45 liter capacity flask that
comes with varios these days like the one that failed the test for thermal
effects. Insulating one of these might be acceptable but there is no way to
insert a copper scrub pad.

Bill Daniels