Originally Posted by
Calculon
Why would a litre of something need to be a liquid? It’s a unit of volume. One litre is 1/1000 of a cubic metre.
It wouldn't need to be liquid. I was having a bit of absurdist fun for the sake of visualization (e.g., "a metric unit of capacity, formerly defined as the volume of 1 kilogram of water under standard conditions, now equal to 1,000 cubic centimeters (about 1.75 pints)").