Dr. Scoville dissolved one grain (0.0648 grams) of raw hot pepper in 100cc of alcohol, and let it sit overnight. He then put a small drop of this liquid on a volunteer's tongue. If the volunteer could taste it, Scoville would dilute the alcohol with water, and test it on the tongue again. He would continue diluting and testing until there was no sensation of heat. If a single drop of this alcohol-and-pepper solution had to be diluted with 30 drops of water, then that pepper would rate at 30 Scoville Units.