Chris:

Thanks, as I am not a chemist, I had no idea on the solubility, but my observation was that when water evaporates, it does leave the residue of minerals sittingbehind.

So I guess the Laws are still right - with the higher temperatures, the minerals are less soluble, and thus more likely to precipitate out, and when the water evaporates, it leaves the residue.

Whew, I'm glad I got all that straight in my own mind, and I now know where those deposits are coming from.

This also tells me that some sort or distilled or deionized or "softened" water is still the best in batteries, in cooling systems, and even in your own home's hot water heater (and as I am an architect, I know that be a real fact )....Andras