The radiation-tainted water of the planet Scalos, which speeds up anyone who drinks it until they move too fast to be seen, used against Kirk in Wink of an Eye.
Scalosian water is the polluted water supply of Scalos, featured in The Original Series episode Wink of an Eye, set in 2268.
Volcanic eruptions released radiation that contaminated the water, hyper-accelerating the Scalosians so that to ordinary eyes they are invisible and are heard only as an insect-like whine. The change also left their men sterile. Queen Deela's people therefore dose visitors with the water in order to take mates from among them, and Kirk is accelerated when a sample is slipped into his coffee. Crewman Compton, taken the same way, dies quickly when he is injured, because damage is fatal to newly accelerated cells.
Spock and McCoy devise a counteragent. Spock deliberately drinks the water to reach Kirk, and the two return to normal time after disabling the Scalosian refrigeration device.