Avast me hearties! Tot of rum to warm me tum…

by Gareth Smith

Proofing Rum

 Ahaaargh me hearties, yo ho ho and a bottle of rum – it be International Speak Like A Pirate Day, and which of us scurvy dogs wouldn’t wish to splice the mainbrace with a tot of rum? But how can we be sure that the Captain isn’t giving us weak watered-down rubbish rather than proper puts-hairs-on-your-chest overproof stuff. Read on and I’ll tell ye…

 Nebrot CC-BY-SA

Rum has a long history with seafarers since its first recorded distillation in the sugarcane plantations of the Caribbean during the 17th century. The Royal Navy adopted it as the drink of choice for sailors (it replaced French brandy) after the capture of Jamaica in 1655 and it was usually served neat, or with lime juice to keep away the scurvy. Later on water was added in an attempt to stop the sailors getting too drunk and this was called grog. Incidentally the rum ration continued in the navy until it was abolished in 1970. However the monarch, or one of the royal family can still give the order to splice the mainbrace.

Pirates and privateers’ version of grog was called bombo or bumbo, which consisted of rum, water, sugar and nutmeg or cinnamon. Pirates had less need of lime juice as their diets were generally better than those in the Royal Navy.

But, shipmates, back to the rum ahhaaargh. I used to wonder how you could get certain rums that were more than 100 degrees proof as they claimed on the bottle, naively believing that 100 degrees proof must be 100% alcohol. Well the proof scale was developed in order to prove to the jolly jack tars that the rum they were being given was of a certain strength. How they did this was to mix the rum with gunpowder and then set fire to it. If the gunpowder wouldn’t ignite then the rum was underproof. Gunpowder will not burn in rum that contains less than around 57% alcohol by volume (ABV). Therefore, rum that contained this percentage of alcohol was defined to be “100°” (one hundred degrees) proof. Pure alcohol comes in at about 175 degrees proof.

These days rum is sold using ABV by law, but there are still some brands that also use the old and more romantic proof scale. Shiver me timbers.

“Capture-of-Blackbeard” by Jean Leon Gerome Ferris – Public domain



Remember landlubbers, if ye be wanting t’ speak like a pirate, but are too lilly-livered t’ get yer
words int’ right order, take a walk to this ‘ere online translator, ‘n twill help ye out.




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Posted in Chemistry, Exploring Science
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