I've tried searching everywhere, but I can't seem to find anything related to how the quantities got named!
- Electric current
- Quantity of a substance
- Light intensity
Most of these derive their names from colloquial usage, and their origins can be found in etymology dictionaries, which also usually give pointers on the first scientific usage.
For example, temperature derives from Latin "temperatus", due proportion, and was in usage since 1530s, it was first used to denote the degree of heat by Boyle in 1670s. Mass comes from Latin "massa", kneaded dough, lump, old French "masse" was used to denote bulk size/quantity since 14th century. Newton writes in Principia (1687):"it is this quantity that I mean everywhere under the name of body or mass. And the same is known by the weight of each body for it is proportional to the weight".
Electric current is two words. Gilbert used Latin word “electricus” (amber) in 1600 to describe attraction that certain materials exhibit when rubbed against each other. A few years later Browne wrote several books based on Gilbert’s work, and he used the word “electricity” to describe the phenomenon. Around 1746 Watson and Franklin suggested that positive and negative charges were surpluses and deficiencies of a single fluid, Watson called it electrical ether, and the flow of it electric current. In 1747 he sent a current through a 6,732 foot long wire at Shooter's Hill in London.
And so on.