“Donovan’s Apothecary Porter”

Irish Brewing Expert M. Donovan’s Remarkable Foresight in 1826


We have encountered Michael Donovan before. He was a Dublin-based chemist, and one of the last apothecaries, those licensed to sell drugs. Apothecaries lost identity when the colleges of physicians and surgeons, and pharmacy (druggist or chemist) professions, took modern shape from the early 1800s.

I mentioned him earlier for his masterful summing up of porter’s origins and where it was going after better science modernized the mashbill, notably by ensuring pale malt carried most of the load to make the alcohol.

Donovan should be remembered as much if not more so for an article he wrote in the Dublin Philosophical Journal and Scientific Review, Volume 2, in the very early year of 1826. In this article, he proposed that wood casks be replaced by barrels similarly shaped, but made from tin. In this, he forecasted the adoption by brewers finally of metal casks, albeit it would not occur for another 130 years.

He explains in the article a problem which has bedevilled lovers of cask ale to this day: continual tapping of the cask permits the carbon dioxide in the cask to take the space left by the evacuated beer; the beer soon becomes flat or will spoil. He sought to emulate bottle-conditioned beer. This is beer bottled with its residual yeast to continue a slow conditioning. Such beer lasted much longer than cask ale, he noted. He said the pressure of the evolving CO2, which could not escape the bottle, precluded at a certain point the formation of further CO2, i.e., arrested fermentation and the beer stayed fresh.

He may not have understood that air entering the cask from the vent-hole oxidizes the beer. But he was right, I think, that maintaining sufficient pressure in a sealed cask would keep the beer stable for longer. Perhaps he realized that a small amount of oxygen in the cask won’t harm the beer. In fact, it is beneficial, brewers speak of the yeast “scavenging” oxygen in bottle-conditioned beer.

For cask beer, all depends of course on rapidity of the dispense – speed of turnover – and how carefully the cask is handled in the cellar. But anyone familiar with cask or real ale knows the problem. Ingress of air may be benign or possibly even assist taste or texture, but only for a short time. The Waterloo of flat and vinegary beer is always nigh.

Donovan’s solution? Build a sealed cask made of tin. He proposed a condensing syringe be used to force air into the cask to send the beer to the bar. In effect, he was advising that compressed air be used, which later became the standard way to dispense naturally-conditioned beer in Scotland. The Scottish system, now abandoned except for a few traditional bars, is called tall font (or fount) dispense. Fonts are tall metal housings with a manual tap. In the cellar, a machine operated by hydraulic pressure or electricity creates compressed air, the so-called fourth utility. It is injected into the cask. Once the tap at the bar is opened, the air pressure pushes out the beer which gushes in the glass to produce a creamy head liked by Scots drinkers.

Some readers may know the party pump for a small keg of draught brought to a party – same idea.

028_2Using air in this fashion does not go contrary to traditionalist, real ale “rules” for beer dispense, since just air is used. No gases such as CO2 or nitrogen are injected.

The earliest compressed air dispense started in Scotland in the 1870s. The “Albany” system was the first – no apparent connection to the American city or its beer tradition. The beer itself was still in wood casks. Either compressed air was put in and the cask permanently closed (hard-pegged) to exclude external air, or, some beer was dispensed by its natural pressure and then the cask was pegged and the compressed air added to raise the remainder to the bar.

Wood continued for all draft beer packaging, in fact, anywhere, into the 1950s but since then has been mostly replaced by aluminum or other metal barrels.

The Scots compressed air system was a partial adoption of what Donovan proposed. A more complete one arrived with the adoption of metal barrels, which had a further advantage over wood: no porosity in the frame. Whether Donovan was involved in or benefitted from the first use of compressed air beer dispense in the U.K., I cannot say. The English stuck with their hand-pulled, and for a time, electric metered dispense, until the 1970’s when pressurized, filtered ale and fizzy lager whittled away at that tradition.

Scottish tall font dispense withered too, under the same, er, pressures, until the craft revival partly reversed this in both places. Still, when real ale came back in Scotland, it was usually in hand pump form, the form that is England always favoured. This was because the tall brass fonts could be mistaken by some to dispense filtered, CO2-pressurized beer. Bar owners reverting to or adopting real ale installed the English paraphernalia as it looked more authentic.

It should be said too, pushing air into beer is felt by modern brewing scientists to be contrary to good brewing practice, in that oxidation risk is increased. In fact though, reports I’ve read of Scots compressed air dispense, where it endures, do not mention undue issues with oxidation. I wonder if the oxygen coursing through the closed cask is scavenged by the active yeast in the beer – either that or the beer is sold fast enough that it doesn’t matter – or both.

The Bow Bar, EdinburghBack to porter in Ireland: some bars in Dublin in the 1950s were also using a form of compressed air dispense, apparently a jerry-rig. In a 1996 article on Guinness history, it was said (see the section entitled Nitrogen. It’s A Gas, Man) the scientists who developed the famous nitrogen dispense system were inspired by this field expedient. Why? Because air is partly composed of nitrogen and that assisted the beer to be soft and creamy, as indeed the “nitro” system pioneered by Guinness does.

Michael Donovan couldn’t solve every problem especially at the dawn of modern brewing science, but his article is remarkably prescient. It may be the first to propose the use of metal for beer casks.

Which Irish brewer, and it should be an Irish brewer – but if a Scottish one wants at it, or a North American one, that’s good too – will:

i) brew Donovan’s recipe for porter (see pg. 202 in particular), and

ii) dispense it by compressed air as he proposed?

Call it Donovan’s Apothecary Porter, will you? Let me know.

Note re images above: The first image, of late-1800s Dublin, was sourced here. The second image shown was sourced from the Scottish Licensed Trade News, here. Both are believed in public domain. The third image, from the Bow Bar, Edinburgh, was sourced from The Guardian, here. All are believed available for educational and historical purposes. All feedback welcomed.