Gunpowder Proof - The Explosive Origin of the Alcohol Proof System

Have you ever wondered where the term ‘alcohol proof’ came from or what ‘100 proof’ means or why 100 proof in the UK is different to 100 proof in the US? Well, wonder no more.

The term ‘alcohol proof’ was first coined in 16th century England and refers to a test to demonstrate the potency of an alcoholic spirit. Historical accounts of the test vary and it quite possibly could have been conducted using a number of methods, all with similar base principles. That said, there are many false truths regarding the origin and intent of this test in circulation and it took some investigating to separate myth and legend from credible facts.

Know your alcohol

An alcoholic spirit at its most basic is a solution, a mixture primarily of alcohol (ethanol) and water. Alcohol is more volatile than water and alcohol vapour will ignite if exposed to a naked flame. Water will not, so as you increase the ratio of water to alcohol in a spirit, it will eventually reach a point where the spirit will no longer produce enough flammable vapour to ignite.

So, if you want to test the potency of an alcoholic spirit, why not simply try to set it alight? Good question.

Most people will tell you the alcohol proof test was conducted by mixing a small amount of the spirit to be tested, with a quantity of gunpowder before attempting to set it alight; but why use gunpowder at all?

Keep your powder dry

The term ‘keeping your powder dry’ reputedly originated in an account of Oliver Cromwell during his Irish campaign in the mid-17th century, in which he instructed his troops to ‘put your trust in God; but mind to keep your powder dry’. However, the term was no doubt in common use far earlier by soldiers and sailors employing gunpowder-based weapons from at least the 12th century.

Gunpowder, or black powder, burns quickly when ignited and is a mix of 15% charcoal (fuel for the combustion reaction), 75% potassium nitrate (a source of oxygen for the reaction) and 10% sulphur (which lowers the reaction’s ignition temperature and acts as a fuel). The ingredients of gunpowder must be combined in a way to produce the physical conditions to facilitate combustion i.e. thoroughly mixed and ground together to the required consistency. This is important because if the mixture is disrupted, the gunpowder will not combust as desired or even ignite at all.

Gunpowder is hygroscopic, meaning it tends to absorb water and when damp will not ignite. The reason for this is the main ingredient of gunpowder, potassium nitrate, is soluble in water. Put simply, this means that if exposed to enough water, the potassium nitrate in gunpowder will dissolve, removing it from its delicate arrangement with the carbon and sulphur, making the gunpowder harder or impossible to ignite.

Some commentators claim that high strength spirts were required for naval operations due to their storage in close proximity to the ships gunpowder supplies.

The high alcohol or overproof strength would ensure that if the rum or gin splashed on or mixed with the gunpowder, the powder would still work. This suggestion is complete nonsense.

Gunpowder and ammunition was stored on board ships in the ship’s magazine, much like explosive ordnance still is on today’s warships. Any other hazardous materials are segregated from the magazine to minimise the chance of accidents or catastrophic events. All attempts were made to keep gunpowder dry on a ship, ensuring it was only exposed to the elements immediately prior to use. In fact great care was taken to protect the magazine from enemy fire, vermin and stray sparks or embers. It is ludicrous to suggest that a sailor’s grog had to be kept at high strength just in case it spilt on the gunpowder it was supposedly stored with.

Liquid currency

I have read many accounts of the origin of alcohol proof, complete with some rather tenuous reasons why things occurred. What was the purpose of this test in the first place?

In the British Empire, distilled spirits, often rum, was used as a form of currency where traditional notes and coins were in short supply. If you were a sailor being paid in rum, you would want to know your payment was to a certain standard and not watered down would you not? If that was the case, then I can understand why a test was developed.

Additionally, if this was the initial purpose of the test it may explain why gunpowder was used rather than just setting the spirt alight? Theatrics. It is a far more satisfying conclusion for a sample to burst into flame and smoke with a bang, rather than to burn silently with a barely visible flame. Perhaps quite a show was made of proving the strength of the rum ration? Or perhaps the test was just a means to part young and impressionable powder monkeys from their rum ration, rather than something conducted routinely on the ship?

The alcohol proof test is commonly agreed to have consisted of mixing an alcoholic spirit with gunpowder and then attempting to ignite it.

If the water content of the spirit was too high, the gunpowder would be left too damp to combust, once the alcohol fumes had burnt off. This was not the most scientific of tests since external factors such as temperature, the ratio of gunpowder to liquid or the time waited after soaking before igniting would affect the results. But if the intent of the test was to make a show, science had little to do with it.

At the end of the 17th century, the British Empire regulated distilling, simultaneously encouraging the distillation of alcohol and imposing a tax on it. 

Navy Strength

This relationship between gunpowder and rum probably explains why gunpowder became an intrinsic part of the alcohol proof test, at least within the British Navy. It would also make a convincing story of where the term ‘Navy proof’ comes from when describing a particularly potent alcoholic spirit. Unfortunately, that is also a fallacy. The term ‘Navy proof’ was first used in the early nineties - nineteen nineties - by an astute advertising department for a popular gin brand.

The tax man cometh

At the end of the 17th century, the British Empire regulated distilling, simultaneously encouraging the distillation of alcohol and imposing a tax on it. The tax was introduced as a way of controlling the production and sale of alcohol, curbing over intoxication, drunken behaviour and crime and last but not least, raising government revenue. Alcohol content was of little concern to the tax man at first, with gin being taxed at a lower rate than strong beer, until the introduction of the disastrous Gin Act 1736 and the more successful Gin Act 1751.

Some suggestions have been made that the alcohol proof test was used for tax collection purposes prior to the 17th century.

I could not find any evidence to support such claims. Although it does present a nice setup and believable reason why the test was invented; who doesn’t want to believe it was concocted by the government of the day so that they could tax the working man at a higher rate? Although it is believed the alcohol proof test originated in the 16th century, it is likely the practice became more common after regulated alcohol taxation was introduced and prior to more scientific means to test alcohol content were developed.

100 Proof

The alcohol proof test was used to determine if the alcohol contained within the tested spirt was above a certain concentration, rather than to gage the exact strength of the spirit. The numeral 100 in the term ‘100 proof’ appears to be an arbitrary figure used to denote the transition point between being under or overproof and was used for no other reason than as an easy way to communicate a greater or lesser alcoholic strength from the standard.

The scientific method

In the UK, the proof system for testing alcohol content was eventually replaced by measuring specific gravity, with a standard being agreed upon in 1816. By comparing the density of an alcoholic spirit with that of distilled water at the same pressure and temperature, is possible to accurately measure a spirit’s alcohol content. A spirit at 100 proof was measured to be approximately 57.1% alcohol by volume or ABV.

In 1824 the French chemist, Joseph-Louis Gay-Lussac proposed a sensible proof scale based on ABV, where pure water was considered ‘0 proof’ and pure alcohol or 100% ABV was considered ‘100 proof’.

That’s not how we do things in America

In 1848 the United States of America introduced its own alcohol proof system where 100 proof was defined as 50% ABV. Why? I have no idea. Perhaps because larger numbers are more attractive to consumers, so marketing something as 80 proof (40% ABV by the US scale) is more desirable than the same product labelled as 40 proof?

So there you have it, the explosive origin of the alcohol proof system.

Did you learn something from this article or do you think I’m wrong? Please let me know in the comments and I will produce more content like it in the future.
- Whisky Dad

The Macallan 12 Year Old Double Cask Impressions

What is it?

Distillery: The Macallan

Name: 12 Year Old Double Cask

Make: Single Malt Scotch Whisky

Extra Info: The Macallan are very particular about the casks they select to age their whisky in, believing the cask wood to be responsible for imparting two-thirds of the whisky’s final aromas and flavours. Fast growing American Oak, from Ohio and Missouri, is selected for its dense tight grain structure which imparts lighter flavours of vanilla and fresh fruits to the spirit. Slower growing European Oak, from the northwest of Spain, is selected for its porous grain structure, imparting more tannins and richer flavours of dried fruits and spices.

Why did I buy it?

I didn’t. This bottle was a gift after attending the Sydney Toast The Macallan event in June last year. The event celebrated whisky from The Macallan, but in particular the launch of The Macallan 12 Year Old Double Cask onto the Australian Market. Sietse Offringa, The Macallan Brand Ambassador and now Head of Education at Edrington,  hosted the event on the night; that's his signature on the bottle. The 12 Year Old Double Cask is matured in a combination of European and American Oak ex-Sherry casks.

What did I think of it?

Presentation: Classic Macallan packaging, clean and premium looking.

Appearance: Naturally bright gold in colour and chill filtered for clarity. Bottled at 40% ABV which is the minimum for a whisky.

Aroma: Yeasty, bread dough, sweet vanilla cream and a hint of further sweetness like munching on milk chocolate coated sultanas.

Flavour: Velvety mouthfeel, smooth and light, orange rind but not too bitter, some hot spices prickle the palate towards the finish.

Finish: Medium length, dry, malty aftertaste lasts but spice fades quickly.

Would I buy it again?

Yes, some whisky from The Macallan can be rather expensive, primarily because of their rarity, but the 12 Year Old Double Cask is reasonably priced and commonly available. The Double Cask is lighter than a typical ex-sherry cask matured whisky but I quite enjoyed it.

Disclaimer: I do not claim to have the nose and palate of a Master Sommelier, however, I am working to train my senses to better identify whisky aromas and flavours. Consider all my whisky 'Impressions' to be a work in progress and I hope to come back to each of them in the future to see if I notice anything different. Most importantly, I'm not just throwing around random aromas, flavours and adjectives for the hell of it; I am trying really hard to critically describe each whisky I taste - WhiskyDad.

Book Review: Whisky by Aeneas MacDonald

Prominently displayed on the most recent reissue cover of Whisky, by Aeneas MacDonald, sits a quote from renowned whisky expert Dave Broom, which reads:

The finest whisky book ever 

That’s quite a bold statement to make but much like the mysterious Aeneas Macdonald himself, it should be considered in context. Whisky, is an odd book; in fact, the original published in 1930 was one of the first books written on the subject, quite surprising considering whisky has been around for much longer than that. The best feature of this 2016 edition is the addition of commentary and annotations by Ian Buxton. I enjoyed Ian’s analysis and what it brings to MacDonald’s book and am glad I bought an annotated edition rather than an unadulterated version, but let me explain why.

Will The Real Aeneas MacDonald Please Stand Up?

Aeneas MacDonald was a pen name, for George Malcolm Thomson, born in 1899 and founder of the Porpoise Press – original publisher Whisky. MacDonald (used from this point on for simplicity) made a conscious decision to keep his real name out of the pages of his book, part of which was to avoid accusations of hubris for self-publishing his own work; something that has less of a stigma these days.

Whisky, is not the kind of book you would find published on the subject today.

It is light on facts and well-research material but rather, is filled with strong opinions that set the conditions for whisky snobbery for decades to come. I recognised many of MacDonald’s sentiments shared by my own father, passed down to him by his father. For example, broad reaching opinions like the superiority of Highland whisky and inferiority of Lowlands whisky in comparison. MacDonald was no whisky expert, although he was clearly a fan and a staunchly patriotic Scott. In writing his book, Macdonald would have drawn on earlier trade publications, his own opinion seemingly formed primarily from those of his old Edinburgh University professor and a splash of myth and legend.

What makes Whisky stand out from other whisky books is its differences, as explained in the Forward by Ian Buxton:

Too many of today’s whisky books are little more than lists: handsomely produced, well illustrated and comprehensive to a fault but with the soul of a draper’s catalogue. Others might be mistaken for material straight from the distiller’s own well-funded publicity machine, and a third category distributes marks out of a hundred to Glen This, Glen That and Glen The Other with mechanical certainty of a drab provincial accountant. 

Despite its faults, of which there are many, you should be able to appreciate why Broom considers Whisky by Aeneas MacDonald to be such a fine book on the subject.

But What of The Book Itself?

While some of MacDonald’s book may be grossly outdated or simply incorrect, some of it is still true today and at times even contemporary in attitude, such as his views on distillery transparency. MacDonald shares his views on what separates whisky from other alcoholic drinks such as wine, expressing his disdain for ‘the drinkers-to-get-drunk’ who imbibe whisky not for pleasure but ‘simply in order to obtain a certain physical effect.’ MacDonald laments the status of whisky at the time as merely a potent spirit rather than a complex and prestigious drink to be appreciated by connoisseurs and offers readers this delightful definition:

Whisky is a re-incarnation; it is made by a sublimation of coarse and heavy barely malt; the spirit leaves that earthly body, disappears, and by lovely metempsychosis returns to the world in the form of a liquid exquisitely pure and impersonal. 

MacDonald touches on the history and production of whisky in his early chapters making a few generalisations that are simply untrue today, such as a distinguishing factor of Highland whisky being a ‘smokiness’ from the malt being dried in peat-fired kilns; or simply incorrect such as his confident proclamation that the cask the whisky is matured in imparts no additional qualities to the whisky other than colour. Peated whisky is more commonly attributed to the Islands region of Scotland these days, but there are always exceptions and cask maturation does have a significant effect on the flavour and aroma of whisky.

Of interest to me was the short section on Campbeltown at the time of MacDonald writing in 1930. Campbeltown is my favourite Scotch whisky-producing region, although it only contains three active whisky distilleries today. In 1930 there were 122 distilleries in Scotland (there are around 100 now) of which ten operated in Campbeltown, including my namesake Kinloch Distillery. MacDonald describes Campbeltown whiskies as:

…the double bases of the whisky orchestra. They are potent, full-bodied, pungent whiskies, with a flavour that is not to the liking of everyone. 

At the time of writing his book, Campbeltown whisky was in the midst of crisis with most of the local distilleries closing in the 1920s and ‘30s in a geographically small region once home to 28 whisky producing distilleries.

The final chapter in MacDonald’s relatively short book is titled ‘Judging, Purchase, and Care’ and most of the information contained within maintains its relevance to this day.

Whisky by Aeneas MacDonald is a time capsule in Scotch whisky appreciation. Part poetry, part prejudice and very Scottish. The book’s charm is in the differences that distinguish it from modern books on the subject, but it does benefit from the moderation of Ian Buxton, who brings a layer of facts and informed interpretation to many of MacDonald’s more controversial claims.

Recommended, but approach Whisky by Aeneas MacDonald as more of a delightful curio, rather than a modern whisky reference.

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