Scoville; Wilbur

In 1912, Wilbur Scoville devised a hotness unit for chilis. The method he used was as follows - 'One grain of ground capsicum is macceated over night in 100cc. of alcohol. After thorough shaking, filtered. This alcohol solution is then added to sweetened water in definite proportions until a distinct but weak pungency is perceptible on the tongue'.

By this method, all the common varieties were progressively diluted, until they could no longer be sensed by the tongue. The stronger the chili, the more dilution it required. Habanero chilis (Scotch Bonnet) rate 200,000-300,000 Scoville, while Jalapeno"s (on average) a mere 3,000.