[Cob] Thermal mass

[paul]

Can anybody post a table that compares the thermal mass potential of cob versus concrete and other materials?  I've had terrible luck finding such a comparison.  I did find one interesting table that basically showed that concrete has an unusual ability to store heat, and that water stores even more than that (like twice as much).  Water turns out to be the best thermal mass but so far I can't figure out how to build a house out of water.  I'm working on it though.

I like the idea of passive solar but it's kind of useless to believe that it can heat your home in temperate zones unless you have a huge thermal mass and that angled glass (probably pretty expensive) that takes the rays of the sun and puts them directly into the mass. I believe that can do wonders, but aside from concrete I don't know of another building material with that kind of thermal capacity.

Any links or even memories of, say, how massive a cob or adobe wall would have to be to equal so many inches of concrete?