Nanodistilling

Johann Conrad Barkhausen (Barchusen in the Dutch) was a chemistry teacher in Utrecht around the year 1694. He ascended to professor at the University of Utrecht in 1704, and held that post until his death in 1723. His apparatuses for distillation are very similar to Charas and other French chemists. Glassblowing and glass materials by this time were advanced, but the distillation designs were not particularly unique amongst the chemists of this period.

That aside, the “pretzel-twist” condenser used by Barchusen is remarkable because of its unusual shape. It is essentially one long glass tube, bent into a helix shape. It is an air-cooled design.

In the ancient design, we see about 8 bends for the hot vapor to make its way to the apex of the condenser, and then another about another 8 bends for the condensate to fall by gravity. The intersections are NOT connected; this is one continuous conduit.

A modern-day Barchusen condenser has been constructed by our glassblowing partner, Q-Glass, as part of our research grant from the ADI. The bottom fitting is 29/40 ground glass, adapting it to a standard 3000mL round bottom with a digital heating mantle. In operation, the ascending 7 bends act as theoretical plates of separation. Vapor rises from the boiler through these, and air cooling of the unit returns liquid by gravity. The liquid interfaces with the vapor at each tight bend.

There is no liquid coolant on this ancient column. Like the designs from Chagas, LeFevre, and della Porto, we suspect this may have been operated outdoors, or in a cool cellar, or even in a colder season. We are using this in an air-conditioned distillery, at around 69’F at the time of this first run.

VERY CAREFUL temperature control is needed on the boiler. If the boiler is driven too hot, hot vapor will travel through the entire unit and condensation will occur in the receiver. If the boiler is driven too cool, hot vapor will not reach the peak and the condenser will operate in reflux with no condensate return past the apex. With a lot of practice, we were able to get the hot vapor right to the apex, and we received condensate at about 1 drop per second into the receiver.

Using a 7% strawberry wash (2650mL charge), this condenser gave REMARKABLE separation: 89% ABV in the first fraction of heads, and 92% ABV in the second fraction of hearts. There was a distinct pause between these fractions, and the temperature on the heating mantle needed to be adjusted.

WHAT’S NEXT – A lot more work is needed to fully characterize this condenser. Knowing the temperature profile at each bend in the twist, in real-time, is paramount. To try to keep to the ancient style of this still, we will probably not wire thermocouples and a DAQ all over it. Liquid crystal temperature indicators are cheap and small, and this may be enough.

A better temperature control on our boiler is needed as well, and we are thinking of placing the reference just below the apex and moving it out of the boiler.

We will update this post as we continue to learn this ancient still!

Our kudos to Dr. Johann Barchusen, requiescat in pace.