148 THE NATURE OF ANIMAL LIGHT 



ture, luminescence will occur with an oxygen pressure 

 of 583 mm. Hg. 



A somewhat analogous case is presented by the oxi- 

 dation of pyrogallol solution in contact with ozone, except 

 that in this reaction too high a concentration of pyrogallol 

 will hinder the oxidation. I have not studied the effect of 

 varying concentrations of ozone. If oxygen, passed 

 through an ozonizer (the silent electric discharge tube), is 

 bubbled through m/100 pyrogallol, no luminescence occurs 

 at 0°, a fair luminescence at 20°, a good luminescence at 

 50°, and a bright luminescence at the boiling point. If 

 the pyrogallol is of m concentration, no luminescence 

 occurs at 0° or 20°, a fair luminescence at 50°, and a bright 

 luminescence at the boiling point. For a definite tempera- 

 ture, say 20°, no light appears if the pyrogallol is of 

 m concentration, but if we raise the temperature, lumi- 

 nescence can occur. The similarity to phosphorus is 

 obvious. Thus the "maximum luminescence pressure" 

 of pyrogallol increases with increase of temperature. 



We have already seen that pyrogallol can also be oxi- 

 dized, if II2O2 is present, by a great variety of substances, 

 such as peroxidases of potato or turnip juice, haemoglobin, 

 KMn04, K4Fe(CN)8, CrOg, MnOz, hypochlorites and 

 hypobromites, or colloidal Pt and Ag. For convenience 

 we may collectively speak of these as oxidizers. They are 

 recorded in Table 13. No light occurs if H2O2 is absent. 

 In the case of some of these oxidizers pyrogallol will 

 luminesce in dilute concentrations but not in strongi. 

 Also, dilute pyrogallol will luminesce with a dilute solu- 

 tion of oxidizer but not with a concentrated solution of 

 oxidizer. The effect of rise in temperature in these cases 

 also is to increase the "maximum luminescence concen- 



