soap

[sakura]

this kinda comes uder tech, but it's really science: why does soap foam more in tap water than distilled water?

[tracymort]

because the minerals in tap water react with the soap to make the lather. http://www.pbs.org/weta/roughscience/discover/wate
rquality.html#hardness

[SavageMonkey]

You'll also notice that in "hard water" areas soap doesn't lather as well. I live in Kent, so near The Downs ( http://www.kentdowns.org.uk/about.html - meaning lots of chalk in the water), and the soap usually takes a while to lather.

Then when I went up North (to a "soft water" area), the soap just seemed to explode as soon as I put it near water :-)... not literally, of course.... interesting....

[Gef]

I give up!! I have just tried to post a chemically correct answer to the question and it was deemed to contain profanities. The culprit was the word 'sc-m' where the dash represents the letter 'u'. This is the correct chemical term for the substance that forms when soap is used in hard water reducing its lathering properties. I suggest you do a google search for soaps and hard water.