Now i will have to look into this.  i suspect that it depends
on the salt content of the concrete, and whether it is wet or
not.  I'm pretty sure dry concrete by itself insulates.
However, there is reinforcing iron bars/wire mesh in most
floor slabs.  wet concrete might couple nicely to the metal.
alice


> Sean Breheny wrote:
> >
> > Why should cement be conductive? Because it holds water well?
> >
> > Sean
> >
> > At 11:06 PM 4/26/00 -0400, you wrote:
> > >I did my demonstration of a Tesla coil discharging into a metal rod in my
> > hand
> > >with a flourescent buld in the other hand once for a high school and didn't
> > >realize that the floor was cement under the tile.  Talk about a hotfoot, even
>
> I believe the silica existent at the sand attracts water, even from the
> air, so it should be also one of the reasons why cement is always colder
> than air and somehow a thermal conductor.
> Wagner.