Alternative origin for Gunpowder Proof Rum

Interesting take from the Smoke and Oakums folks, what does everybody think of this?

https://sites.google.com/site/gunpowderrum/gunpowder-proof

The generally held notion of what the 'gunpowder proof' test was all about is that it was a means of testing to see if the sailors' daily rum ration had been watered down by the unscrupulous Purser (whose role it was to manage the shipboard supplies so that they lasted the voyage).

While it is true that the position of Purser aboard a ship was a lonely and unloved one it would be an inaccurate description of Navy life (where the rum ration was a fixture) to suggest that the crew had much say in how he performed his task.
One has only to read accounts relating to crew complaints about treatment and conditions that lead to the famous mutinies at the Spithead and the Nore in 1797 to realise that complaint was not undertaken over trivial matters.
If the Purser watered your rum... well you took it and pulled your forelock respectfully.

I would like to suggest an alternative explanation of what the rum-gunpowder test was all about: it was to test the quality of the gunpowder.

Aboard the floating gun platform that was a ship-of-the-line the efficient operation of the ship took precedence over the comfort and lives of the crew. Knowing the quality of the ship's supply of gunpowder was rather more important than knowing the alcoholic kick of the crew's 'tot'.

To this end rum (or any high-proof spirit) was/is a useful tool for a reason of basic chemistry:

Saltpeter or potassium nitrate (which is usually around 70% of the make up of black powder) does not dissolve very well in pure alcohol, but it will dissolve in water.

A gunnery officer, knowing this fact, will be able to test the quality of his powder by using the 'gunpowder test' described above. If good quality gunpowder was soaked in 'over-proof' rum and then allowed to dry out again it should flare up when set alight (providing the powder grains are not too spread out).
This is because the high percentage of saltpeter (the most expensive component in gunpowder) will stop the powder grains from dissolving into a black sludge that will not combust (there must be gaps between grains of gunpowder for the oxygen-fed chain reaction to occur).
Poorer quality gunpowder (i.e. that has too much charcoal or sulphur in it) will dissolve on contact with over-proof rum and, when dried out for the test by flame, will be found to be a non-combustible sooty mess.

This, to my mind, is the real story to the 'gunpowder-test' (note that it is called the 'gunpowder-test', not the 'rum-test'). Out of this important trial-and-error quality test probably grew the Navy's insistence on storing 'over-proof' rum for use aboard ship. Under-proof rum would dissolve any and all gunpowder grains (due to the higher water content) leaving the gunners without a proper way to check the chemical make-up of their powder other than by tasting it (not such a crazy notion - potassium nitrate is a food-grade mineral salt - better quality gunpowder would taste saltier than a lesser product).

And how important is it to know the make-up of your powder, you might ask?

Consider the scenario of a gun-crew preparing to fire on an approaching enemy using a cannon loaded with un-tested powder. Should the powder have been adulterated by an unscrupulous supplier it may not ignite (leading to defeat, capture, imprisonment, or worse for the luckless crew). Or the cannon may fire but with the mix being too weak on explosive force leading to the ball falling short of the enemy... Or, in a worse case outcome, the mix may be the opposite and too much for the cannon, leading to an explosion that kills the whole gun crew.

Russian roulette with cannons is not for the faint of heart.

Ultimately I would say that the 'gunpowder-test' was primarily about the gunpowder. It was only a secondary outcome that told you whether your rum was over-proof or not (if you had gunpowder of a proven quality you could test the water content of your rum in a nice inversion of the same test - if the rum dissolved even the quality gunpowder grains then you knew it was below 'proof' i.e. had too much water content).

'Gunpowder Proof' is a term describing the tradition of 'proving' the strength of a measure of rum by mixing it with black gunpowder and setting it alight. The alcoholic strength of the rum at which the mixture would flare up (as in the picture on the left) was termed 'proof'. As the Royal Navy were the main proponents of this method of testing the strength of a spirit the term 'Navy Proof' or 'Navy Strength' was adopted.
In the intertwined histories of rum and the navy the terms 'gunpowder proof' and 'navy proof' are interchangeable descriptive terms.

57% abv is the generally accepted percentage strength that defines a spirit as being 'gunpowder proof' or 'navy strength' - but for a description of what may represent 'gunpowder proof' to the Royal Navy you can't go past Simon Difford's explanation as given on the diffordsguide.com website:

"In 1816, proof become more closely defined when Bartholomew Sikes invented an accurate hydrometer, which measured 100 proof at just over 57% alcohol by volume (abv or alc./vol.). Sikes' new scale was adopted by law in 1818. It defined a 100 proof spirit as 4/7 the alcohol purity by volume. Or to put it another way, to convert the percentage of alc./vol. to degrees proof spirit, multiply the percentage by 7/4, or 1.75.

However, the navy had other ideas and, after Sikes' hydrometer was invented, conducted its own tests to establish the strength their rum should be issued at. They collected 100 samples of rum diluted to 'proof' using the old gunpowder test, and then measured the proof of each sample using one of the new hydrometers. The average was 95.5 on the Sikes scale, which equated to 54.5% alc./vol., thus this strength was adopted as 'navy' standard strength.

This measure stayed in place until 1 January 1980, when the United Kingdom adopted the alcohol by volume (abv or alc./vol.) standard to measure alcohol content, as prescribed by the European Union, (according to the recommendation of the International Organization of Legal Metrology) measuring alcohol strength as a percentage of alcohol by volume at a temperature of 20°C. The law was itself essentially a direct manifestation of the Gay-Lussac scale, which measured ethanol as a percentage - rather than in degrees - of total volume.

So true Navy Strength is 54.5% alc./vol. and those brands of spirits labelled as 'Navy Strength' but at the higher 57% alc./vol. strength have confused English Proof with Navy Strength, but at least their gun powder will safely ignite."

published: 14 Aug, 2012

Interesting theory, thanks

Yes, very interesting rum and gunpowder information! One thing I thought was odd in the article is that they stated "there must be gaps between grains of gunpowder for the oxygen-fed chain reaction to occur." I don't think that is true -- the saltpeter (potassium nitrate) is the actual source of oxygen, otherwise how could black powder burn when firmly tamped down inside a cannon? The variation in black powder grain sizes is related to regulating surface area and therefore has an impact on the speed at which the powder burns.

We used to make gunpowder at home when I was in high school and when you could still buy saltpeter over-the-counter as a diuretic or for pickling purposes. Me and a friend, over a period of several months, came up with a little contest to see who could come up with the cleanest-burning home-made gunpowder. I won that contest.

Ace, did you just post on a public forum that you know how to make gunpowder? Welcome to the Department of Homeland Security watchlist. I got here buying raw materials to make thermite :lol:

Not to disparage the effort at all, but I can't buy this alternative theory of the "gunpowder proof test" as a test of the quality of the powder, rather than a test of whether the rum strength exceeds an approximate threshold.

AceExplorer is correct,... the saltpeter is the oxidizing agent, not atmospheric oxygen around the grains. Also correct about grain size: musket powder had smaller grain size, for a faster burn/explosion. Cannon powder was "slower" large grains, to keep from blowing the cannon apart. Also, proportions of saltpeter, charcoal and sulfur varied, depending on the intended use. As an old chemistry buff (made black powder, too, back in junior high, early '70s), I don't think any shipboard 18th or 19th century field test with 114° rum would render useful information about plausible variations in the gunpowder.

The analysis seems to be saying that saltpeter will not dissolve well in high-proof (114°, 57% abv) alcohol, but that the charcoal and sulfur will(?). In fact, sulfur and charcoal are not soluble in water, pure alcohol, or any mixture of them. Saltpeter is not soluble in pure alcohol, but it will dissolve in water, and it will dissolve into the water component of rum. If the gunpowder was wet with water or rum, then allowed to dry, it would simply be... gunpowder. Just like before, and of course it will ignite. This would "test" nothing.

Descriptions of the "gunpowder proof test" seem to involve dampening the powder with the spirit, though, not trying to dissolve it. Dampening with water was also used during gunpowder manufacture, to keep it from igniting, and to make the soluble saltpeter more thoroughly 'infuse' and coat the charcoal and sulfur particles. It is far more plausible that the "test" was of the water content of the rum. Too much water in the rum would render the dampened powder unable to ignite. It wouldn't be an exact quantitative measure, and temperature and humidity would affect the result, especially near the burn/not burn threshold. But sailors were not likely worried that the 114° rum had been cut to 111°, or even 101°, but to well under that.

Wayne Curtis, author of And a Bottle of Rum, has experimented with the "gunpowder proof test" several times, with inconsistent results. I think much of the inconsistency comes from methodology - not controlling variables, etc. If he ever visits this again, I hope he includes someone with a chemistry background, who might contribute some "scientific rigor".

"The rum's the thing..."

[ Edited by: Limbo Lizard 2014-04-29 13:46 ]