Fresh cut surfaces of Na and K metal will glow in the dark for some time, especially if warmed to 60°-70° (Linnemann, 1858). A film of oxide is formed over the surface, showing definitely that oxidation has occurred. Ozone oxidizes organic matter with an accompanying glow (Fahrig, 1890; Otto, 1896). The light from ozone acting on pyrogallol solution is especially bright under certain conditions. Radziszewski (1877, 1880) gives a long list of substances, chiefly essential oils, which luminesce if slowly oxidized in alcoholic solutions of alkalis. Formaldehyde, dioxymethylen, paraldehyde, metaldehyde, acroleïn, disacryl, aldehydeammonia, acrylammonia, hydrobenzamid, lophin, hydroanisamid, anisidin, hydrocuminamid, hydrocinamid, besides waxes, and such biological substances as glucose, lecithin, cholesterin, cholic, taurocholic, and glycocholic acids, and cerebrin, all luminesce on oxidation. Radziszewski himself and many other authors have compared the light of organisms to this type of luminescence. Indeed the incorrect identification of granules found in the cells of practically all luminous tissues as oil droplets, is largely due to the influence of Radziszewski's work. Dubois (1901 _b_) has added esculin, and Trautz (1904-5) many aldehydes and phenol derivatives, including vanillin, papaverin, tannic and gallic acids, besides glycerol and mannite to the list of biological substances oxidizing with light production. Guinchant (1905) has described oxyluminescence of uric acid and asparagine, Weitlaner (1911) of substances in humus and McDermott (1913) of substances in urine and the anaerobic alkaline hydrolysis products of glue and Witte's peptone. Pyrogallol is especially prone to luminesce, as was first noticed by Lenard and Wolf (1888) in developing a photographic plate with pyrogallol developer. Later the luminescence was studied in some detail by Trautz and Schloringin (1904-5) who developed the well-known luminescent mixture of pyrogallol, formaldehyde, K_{2}CO_{3} and H_{2}O_{2}. As I have shown, pyrogallol can be oxidized in a great many different ways, and some of these are of great interest, for they very closely imitate the mechanism for the production of light in organisms. These are recorded in Table 3, which also includes various other types of oxyluminescence of general or biological interest. TABLE 3 _Types of Oxyluminescent Reactions_ 1. Oxidation in air spontaneously. (_a_) At ordinary temperatures. [Phosphorus. Fresh-cut surfaces of Na or K. Thiophosgene and Thio-ethers (RCS.OR).] (_b_) At melting or vaporizing points. (Fats, terpenes, sugars, resins, gums, ether, silk and others.) 2. Oxidation in aqueous or alcoholic alkalies. (Many organic substances.) 3. Oxidation in hypoiodites, hypobromites, or hypochlorites. (Many organic substances.) 4. Oxidation in peroxides (H_{2}O_{2} or Na_{2}O_{2}). (Many organic substances.)