We have a hydrometer that has proved VERY useful over the years for these 
type of purposes.

At 12:28 AM 2/14/2000 -0500, you wrote:
>ate: 13 Feb 2000 17:40:31 -0600
>From: aidan.schurr@hvh.co.nz
>Subject: test: absolute alcohol vs 95%
>
>Hi there all,
>
>We store 20L at a time of AA, 95% and xylene within the lab in
>xplosafe containers.  These are filled from 200L drums in our
>dangerous goods store by the orderlies.  It appears as if they may
>have interposed the 95% for AA and vice versa at last filling (milky
>xylene when dehydrating).  Does anyone know of a quick,
>conclusive test to tell which is which?
>
>Thanks in advance,
>Aidan Schurr, New Zealand.