Cool flames were accidentally discovered in the 1810s by Sir Humphry Davy, who noticed that certain types of flame did not burn his fingers or ignite a match. He also found that those unusual flames could change into conventional ones and that at certain compositions and temperatures, they did not require an external ignition source, such as a spark or hot material.[2][5][6] Harry Julius Emeléus was the first to record their emission spectra, and in 1929 he coined the term "cold flame".[7][8]