Nanodistilling

Nicasius le Febure, also known as Nicolas le Fèvre, was born in the Ardenns in the early 17th century. He was a Calvinist and held appointments as a scientist in the French court as the “demonstratur for Vallot” and later in the English court as the laboratory manager at St. James, London. In his treatise, Traite de Chimie (1646, 1660), he sought to improve the design of distillation apparatuses. It is in this work where we find his curious zigzag condenser . Another French chemist, medical doctor, and fellow Calvinist, Moyse Charas, also gives a similar zigzag air cooled design in his Pharmacopeè Royale Galenique et Chymique (1676-1753).

Our reconstruction of the Le Fèvre apparatus used the same number of zigzags as the ancient sketch, which totaled three (Fig. 36). We elected to use 90′ angles in the bends, whereas Le Fèvre and Charas designs are slightly more acute. A careful study of both ancient sketches confirmed that the central rod is used for support and not for transiting vapor or condensate. We used solid glass rods for our support. The top and bottom of our reconstruction uses standard taper 24/40 ground glass joints for ease of attachment to other laboratory glassware. Because of the height of our reconstructed unit, a 22,000mL boiler was selected with excellent results.

The operation of the LeFèvre apparatus, like all of the other ancient reconstructions, requires careful boiler temperature control, a cool ambient temperature, and boiler volume scaled to the apparatus conduit diameter and total path length. Since this was our largest apparatus reconstructed, our selection of 22,000mL boiler was well-founded. In operation, the wash in the boiler is slowly brought to a gentle boil. The room temperature was held at 20°C with air conditioning. As hot vapors entered the zigzag, each section reached thermal equilibrium along the reflux side within ten (10) minutes. This heating pattern was very similar to the Barchusen apparatus. During a distillation run, the point of where condensation occurs is readily visible as the front moves up the apparatus. Hot vapors are moving upwards through a thin film “pipe” of condensate that is returning to the boiler. The 90°C angle at each zigzag provides additional contact surface for intimate mixing of the vapor phase and liquid phase as well. Liquid crystal temperature indicators displayed a 75°C point one at a time as the hot vapors climb the zigzag up to the ambix.

The apparatus operates in simple full reflux until the countercurrent hot vapors and condensate climb through all zigzags against gravity and reach the ambix. Once within the cooler ambix, condensation occurs in the rapidly increasing volume and the condensate falls from the walls towards the solen and into the receiver. In operation, it was important not to overheat the zigzag, else hot vapors will continue to travel through the ambix and exit the solen to the receiver with little to no condensation. In careful operation, the ambix walls are slightly warmer than room temperature and the condensate is returned at or close to room temperature to the receiver flask. At any time, the slight room temperature change may also be adjusted to provide optimal cooling.