Reinhardt,

I think that you are on the right track with your miniaturized still. I think that using the straw as a means of directing the steam to the condensing tin may cause you some problems, though.

First, in order to get as much steam as possible through the straw, you will have to seal the foil on the canteen cup.

Secondly, the steam will be moving through the straw too fast to be able to cool down very much, if at all. There will be virtually no cooling in the tube.

Thirdly, since the steam is expanded, it will need much more room in the condensing tin than it did in the canteen cup while in its liquid form. Even if you greatly cooled the condensing tin, I think that so much steam will escape the tin that it will not be worth your effort.

HOWEVER, if you could condense the steam before it gets to the tin, you'd be in good shape. The condensing tin now becomes just a vessel for holding the already-condensed water, and you may even be able to do without the plastic bag.

You might want to consider replacing the straw and the foil hood with a wide, tapered tube made out of aluminum foil. You want it to be wide because you want to take advantage of the greater surface area available, and you also want the steam to expand and slow down so it stays in contact with the foil as long as possible. Between the slowing of the steam and the heat-conductive properties of the foil, you should get a good bit of condensation with little loss of steam.

You might start with a cone-shaped tube about 3 feet long (for those of you on the other side of the pond, that's about 1 meter). I'd make one end about 50% larger than the boiler to catch any drifting steam, and then gradually taper the tube to about the size of your finger. Gradually bend this tube into a U or J shape and invert it. If you use the J shape, the wide end would be at the shorter end of the J. In either case, the wide end would be suspended just above the boiler, and the other end would be just above the receiving vessel. The rising steam would enter the wide end of the tube and would begin to cool. By the time the vapor got to the far end of the tube, most of it would be condensed.

If the 3 foot tube doesn't produce enough condensation, you might try lengthening it or adjusting the taper.

Please let us know how your idea works out.