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THE MYSTERIOUS BEER BUBBLE – HOW DOES IT WORK?

While visiting son Tom (the Jones Counter man) I enjoyed a few beers with him. He had laid in a stock of Boddington’s, which we both like. As we were popping the pull-tabs we noticed, as always, the initial “pop” as the pressure was released. This was followed by a few seconds of a hissing noise, accompanied by a fine-bubbled foam. When we had finished our beers we noticed that something was rattling in the cans.

Cutting open a can revealed an ingenious plastic bubble. The bubble is equipped with a pair of duckbill one-way valves. One valve admits flow into the bubble from the outside. The other valve allows flow to exit the bubble.

Field testing revealed that the bubble floats round-side up.

Tom and I could not agree on what was happening. We did agree that when the can was sealed, gas departed the beer into the can’s headspace, pressurizing it. Then opinion diverged.

One of us thinks that the plastic bubble has no initial pressure, and that as gas begins to fill the headspace from the beer, it also enters the bubble. The other opinion is that the bubble initially contains an overcharge of CO2.

Whichever is correct, when the can is opened, the headspace is immediately depressurized. Built-up pressure within the bubble then shoots out of the duckbill valve, adding an agitating stream of fine bubbles, until the bubble is empty.

Can anybody explain this with something better than our two opinions?

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The can contains 16.9 ounces, which makes it just over a US pint.

Wikipedia says:The pint is an English unit of volume or capacity in the imperial system and United States customary units. The imperial version is 20 imperial fluid ounces and is equivalent to 568 mL, while the U.S. version is 16 U.S. fluid ounces and is equivalent to 473 mL.
The pint is an English unit of volume or capacity in the imperial system and United States customary units. The imperial version is 20 imperial fluid ounces and is equivalent to 568 mL, while the U.S. version is 16 U.S. fluid ounces and is equivalent to 473 mL.
Ah, but do you know why the US pint is smaller than the standard Imperial Pint used in the rest of the world?

Once upon a time there were some merchants in Boston who imported barrels of port and other alcohol into America. Unfortunately the return trade on the ships was mainly raw materials like skins, so the barrels did not go back. Consequently new barrels were used each time.

Now any one who knows anything about the trade of a cooper knows that a new barrel is not caulked, but it is the natural swelling of the wood, made wet with the contents, that will eventually seal the barrel.

Between the leakage on the seams of a new wooden barrel, and the tendency for alcohol to seep into the wood, and some natural evaporation of the alcohol; by the time it reached Boston the amount in the barrel was less than when shipped.

The merchants, having paid for a 10 gallon barrel would divide the contents into tenths and sell each as a gallon. This got them into trouble with the crown courts in Boston for selling ‘short measure’. A very serious offense.

Chafing at the perceived unfairness of not being able to sell short measures, and having been before the courts on several occasions for this offense, and facing more charges of selling short measure, along with smuggling to avoid the 1% import duty called the ‘stamp tax’, the merchants decided they wanted a revolution.

It’s almost impossible to galvanized a revolution based on, “I want the right to cheat you out of your grog by selling you short measures” so the merchants had to come up with another way to get the locals riled up.

The locals did not like Indians, and the merchants did not like the introduction of tea because it cut in to their alcohol sales, so they staged a fake Indian attack on a tea ship.

The rest is history.

One of the first acts of the new congress was to standardize the new US gallon as smaller than the Imperial gallon that was used in the British Empire and all across the rest of the world.

This rewarded the Boston merchants who had started and bankrolled the war of independence. They could now continue to purchase gallons of alcohol from Europe and the West Indies, in Imperial gallons, and sell them of with no loss in numerical units. With the help of the new law they avoiding being hung for selling ‘short measure’ because the new US gallon (and pint) was defined as smaller.

That’s how America came to be, it was founded by Boston merchants who wanted to cheat the population without getting hung for their crimes.

So ever since Americans have been getting short changed on their pint of beer.
Last edited by jamesm

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