228 



Papers from the Department of Marine Biology. 



Among the substances of class (1) may be mentioned Mn02, mixtures 

 of Mn(0H)2 and Mn(0H)3, HsMnOa, Fe2Fe(CN)6, and AgsO. All give 

 light. I have observed no light with boneblack, Pb02, Ag2Cr04, 

 PbCr04, BaCr04, Ag4Fe(CN)6, Pb2Fe(CN)6, Zn2Fe(CN)6, Cu2Fe(CN)6, 

 HgO, Cu(0H)2, CU2O, CuO, FeO, iron filings, Hg2Cl2, Cr203, Cr(0H)3, 

 Fe(0H)3, Pt black, and silica. 



Among the group (2), a silver sol protected by protein so as to be 

 fairly concentrated gave a good light. Concentrated Pt sol and Au 

 sol also gave light. Colloidal Fe(0H)3 and copper oxide gave nega- 

 tive results. 



Table 22. 



The following salts gave the best light in the concentrations indi- 

 cated: m/10 to m/20 I^Fe(CN)6, m/100 K2Cr207, m/50 K2Cr04 (the 

 light appears only after a long time), m/100 KMn04, m/100 CrOs, 

 m/10 FeCl3. The following gave no hght: K2S2O8 (m/10 to m/320), 

 KCIO3 (m/10), K3Fe(CN)6 (m/10 to m/1000) MnCl2 (m/10), AgN03 

 (2 per cent), CUSO4 (m/10), and bromine water. The mechanism of 

 the action of these diverse substances will be considered in a subse- 

 quent paper. 



Peroxide. — Only H2O2 will give light with pyrogallol and an oxidase. 

 Na202, benzoyl hj^drogen peroxide, quinone, Ba02, or ozonized turpen- 

 tine do not, although they give a strong guaiac reaction with the per- 

 oxidase of turnip-juice. We must also add H2O2 to potato-juice, which 

 already contains an organic peroxide whose oxygen may be transferred 

 to guaiac. It is no doubt in too small a concentration to give light 

 with pyrogallol. 



Oxidizable substance. — Many of the amino- and hydroxy-phenols are 

 rapidly oxidized by potato-juice -I-H2O2, but pyrogallol was the only 

 one which gave light. The following were tried and all gave colored 

 oxidation products: phenol, tricresol, pyrocatechin, resorcin, hydro- 

 chinon,orcinol, a-napthol, ortol, anilin, and p toluidin, a-napthylamin, 

 guaiacol, para-phenylen diamine, amidol, and pyramidon. Phloro- 

 glucin, jB-napthol, and 5-napthylamin were not oxidized. 



Among the glucosides, vanillin, amygdalin, phloridizin, salicin, sapo- 

 nin, and esculin gave no light with potato-juice, either at 20° or 60° C. 



