What weighs more, an ounce of feathers or an ounce of gold? Haha, trick question. It’s the ounce of gold.
The ounce, like the foot, is a measurement that has varied quite a lot over time. The Spanish ounce was the equivalent of 28.75 grams, whereas the Maria Theresa ounce used in Ethiopia and Eritrea was around 28.07 grams. The Dutch ounce is metric, 100 grams exactly. Most of these ounce measures are obsolete now, but a couple still see wide usage.
There’s the ounce used in the United States (technically called the international avoirdupois ounce), which equals around 28.35 grams. It’s used quite widely to measure weight, so this is the obvious way to measure the weight of a substance like feathers.
There is also the troy ounce. It’s an old measure, based on the apothecaries’ ounce, and it is still used to measure precious metals: silver, platinum, and gold. The troy ounce is larger than the international avoirdupois ounce, weighing in at a little over 31.10 grams.
So there you have it, a (troy) ounce of gold weighs more than an (avoirdupois) ounce of feathers. My initial statement is technically correct – the best kind of correct!
[Thanks to Shaun T for suggesting this topic]