The invention of the pot still for alcoholic distillation goes something like this.
Ironically, it was a Muslim who invented the al’embic, or the pot and condensing arm, that allowed alcoholic distillation to occur. The al’chemist Jabir ibn Hayyan (or Geber) did so around 790 AD in Syria. A prolific author, and considered a founding father of chemistry, he’s also credited with inventing over twenty other bits of laboratory kit.
The alembic consisted of three parts: the base pot; the ambix or head, which covers the opening of the pot; and a downward-sloping tube that acts as a condenser delivering the spirit to a receptivity. Combined into one piece, it is a key part of laboratory kit known today as a retort.
The alembic remained a small-scale, simple device through out the Middle Ages. Indeed, remote areas still use this rudimentary device today, as do some mezcal producers. Then with the onset of the industrial revolution rapid evolution took place, developing it into the more nuanced copper pot still of today – with its perfected components the base pot, middle, ogee, swan neck and lyne arm. The condensing tube became a copper pipe, improved by increasing the length and, shaped like a coil and known as a ‘worm’, placing it in a vat of cold water.
In 1825 William Grimble invented the gutturally entitled ‘dephlegmator’, the game-changing shell and tube condenser, Patent #5167. Running cold water circulates around a series of densely packed, parallel pipes creating a large cooling surface area. The alcohol vapour flows up these copper pipes (the cold water surrounding them in the reverse direction) and is condensed more effectively and more economically than a worm coil.
A century earlier, Irishman Peter Woulfe was born near Limerick, in 1727. Part of the Jacobite diaspora, he fled to Cadiz, then on to Paris to study chemistry under Guillaume-Francois Rouelle. He moved to London in about 1750, working in the home laboratory of the Earl of Bute, tutor to the future king George III. In 1767, elected to the Royal Society, he submitted a new way of handling noxious gases via his own design, a square-shouldered, water-filled flask: the Woulfe Bottle. With its two necks, it allowed gases to bubble through water before being collected in second container. By preventing noxious fumes it allowed much stronger acids and alkalis to be made.
THE WOLFE BOTTLE AND APPARATUS
Édouard Adam, of Rouen in northwest France, though illiterate, attended the chemistry lectures of Professor Laurent Solimani in Montpellier. Adam applied the principles of the Woulfe Bottle to distillation, realising that he could make higher strength, cleaner spirit more economically if he combined both the wash and spirit still operations into one, free from the time-consuming and energy demand of charging, boiling off and emptying of two stills. In 1801 he patented the first single operation still. It was an important stepping stone on the way to continuous distillation.
Adam’s still relies on the usual pot but with three Woulfe-inspired mini-pots (called retorts) enabling a single operation to produce high strength spirit, with more effective heat use, and a simple fractioning of the spirit. The version adopted by the rum industry used just two retorts.
Typically the pot contains the 7% wash as usual; the next vessel – or retort – has ‘low wines’ at 35% ABV; and a third has the ‘high wines’ at about 70% ABV. Both the low and high wines are saved from the previous distillation.
As the pot still temperature rises the first alcohol vaporises, averaging at around 25% ABV. This vapour is led to the bottom of the first retort where it bubbles up through the low wines. Crucially, as it does so, the vapour’s water element condenses releasing heat – which in turn vaporises the alcohol in the low wines.
The now-richer alcohol vapour leaving the retort stands around 50% ABV. This enters the second retort containing the high wines. Again, the water element condenses creating heat, sufficient to vaporise the alcohol in the high wines. The alcohol-enriched vapour passes through the condenser to the spirit safe.
The high wines (also known as heads or foreshots), the first spirit to flow into the spirit safe, are high strength and impure: this is kept for the high wine retort. As the spirit strength falls the desirable spirit arrives and the cut is made; this spirit, averaging around 80% ABV, is the ‘middle cut’, or heart, and will become rum. As the spirit strength and quality tails away, weaker, undesirable spirit, flows – these are the low wines, destined for the low wine retort.
The pot still and retorts are emptied, the vinasse going to wastewater disposal. The spirit tank is pumped to the warehouse for barrelling. The pot still is then recharged with wash, the low wines pumped in to the first retort, the high wines in to the second and the cycle is repeated.
Édouard Adam failed in commercialising his invention. The three distilleries built by Adam were not successful. Several distillers, including Solimani, Bérard, Barré, built direct copies or with only minor modifications. Adam died a poor man. However, within two decades, Anthony Perrier, then Robert Stein, and ultimately Aeneas Coffey, succeeded with the continuous still. It is, in essence, Adam’s concept multiplied and in column form. In 1830, Coffey was granted Patent #5974.
But Adam’s still had managed to create something of a legacy in the Caribbean. Perhaps it is because the still was the latest thinking at a time when the Caribbean rum industry was taking off around 1800, a time capsule of distilling history. Perhaps the still was retained for its heavier spirit style – an affectation preferred by the blenders’ economy of “a little goes a long way”, much like the peated whiskies of Islay. Indeed, it might simply be the higher spirit strength necessary for good rum.
Adam’s configuration was superseded by the triumphant Coffey still. And sure, we have one of those too, a state-of-the-art marvel that pushes the possibilities of a column still even further.
But that precise period in distilling history, thirty years that had somewhat defined the Caribbean method, was simply too alluring to us. So to preserve in aspic that era we have also installed Adam’s pot still and double retort, designed by still makers par excellence Forsyths, ensuring that in this quiet corner of Grenada the enterprising Frenchman, Édouard Adam, lives on.
RENEGADE RUM ADAM STILL – MAY 2019