In uk.d-i-y, Dave Liquorice wrote:
On Sun, 23 Aug 2009 14:19:36 +0100, Pete Verdon wrote:

It's difficult to tell - he's just written back and said that he's

fulfilled his legal requirements (the name was correct, the
concentration was wrong)

That's ********. If he offered "Isopropyl alcohol 99.4%" and you bought
it as such, then that's what it has to be.

Quite. It could be a labling error or he could be trying it on.
Before taking further proceedings it needs to be acertained what the
concentration actually is.

I'm not sure how one could do that simply at home.

Measure exactly a litre and weigh it using your digital kitchen scales.
At 20 degrees C, 99.4% will weigh 792g, and 70% will weigh 867g.

See:

http://www.separationprocesses.com/C...Property01.htm

(That table deals in percentages by weight and for all I know yours
could be by volume. But I think it's close enough for your purposes.)

--
Mike Barnes