In concept you're ok, but there are several problems with doing what you intend to do.
What you're doing is essentially an 'inside out' version of the Einstein system, and so you are venting your refrigerant. The key to a closed loop system is just that - a closed loop. For this, you either need a compressor (Carnot cycle), or some other method of compressing and manipulating the refrigerant to recover it so it can do more work.
Einstein's system works on a different idea than the Carnot cycle (compressor), and cools in 'pulses' rather than in a continuous flow. The gaseous refrigerant in an Einstein cycle system is first heated to 'compress' it (fire works), it then moves to another chamber where it is cooled. At this point it condenses to a liquid as it gives up the heat. When the majority of the gas has condensed, the heat is removed, and the refrigerant begins to evaporate, absorbing heat in the process. The cycle must be repeated when all of the liquid has turned back into a gas. During 'compression', the unit does not provide any cooling.
Both systems have the refrigerant completely contained in a closed system.
There are also continuous cycle versions of the Einstein system, but it is much more complicated than the simple 'cold pot' version.
Alcohol doesn't make an ideal refrigerant because of its thermal properties. This is why anhydrous ammonia or freon is used. They have much better suited thermal properties for use as refrigerants.
Anhydrous ammonia can be obtained rather easily, depending on your knowledge of chemistry. Getting it from supply outlets will turn heads however.
I'm not going to say that alcohol can't be made to work, but it is just not really cut out for the job.
Hope this helped.
Steve
EDIT - Realized I had confused the two technologies, even though they are very closely related:
"Icy Ball" -
http://en.wikipedia.org/wiki/Icy_Ball - Manually cycled (as described above) refrigeration. Very simple, no moving parts.
Einstein fridge -
http://en.wikipedia.org/wiki/Einstein_refrigerator - as
mentioned above - Automatic operation, more complicated, but still no moving parts.
Carnot cycle -
http://en.wikipedia.org/wiki/Refrigeration_cycle - "Standard" refrigerator and air conditioner systems. Needs a compressor.
Both the Icy Ball and the Einstein cycle use Ammonia as the refrigerant. The Carnot cycle typically uses freon, although in high volume systems ammonia is also employed.
Steve
