On Wed, 11 Aug 2010 13:24:12 -0700, Dan Abel wrote:

> In article >,
> Sqwertz > wrote:
>
>> I especially see it in my Stroh 80 w/ice cube. That's how you know it's
>> safe to drink - by the correct amopunt of swirl-wave action.
>
> When there are two liquids with different indexes of refraction, that
> will cause this appearance. Once the two liquids have mixed completely,
> there will be no more difference in refraction. Since alcohol and water
> mix completely, when you were a kid, you just needed to mix the water
> into the booze thoroughly before your parents got home.

But at different densities, they will never mix completely - or at least
stay that way for very long. You could see the swirls several weeks later
after several vigorous shakes (parents weren't big drinkers).

Of course they could tell by taste first, then by the swirls for
confirmation.

-sw