210 Aso, "Which Compound in certain plant-juices can liberate iodine etc. 



thus far I was not able to prove it in the way just mentioned, 

 since I encountered some difficulty in the preparation of a 

 peroxidase precipitate sufficiently pure. Further, de fact that 

 purified oxidase does not liberate iodine f rom potassium 

 iodid in acid Solution, shows that it is not an organic 

 peroxid 1 ). However, the possibility of a transient formation of 

 an organic peroxid cannot be denied when the oxidase causes 

 the oxidation of a certain other Compound. Such peroxids 

 are then the first products of an oxidation caused by 

 the oxidizing enzym, and this opinion also that of Bach 

 and Chodat, and differs essentially f rom the hypothesis 

 of Kastle and Loewenhart, according to which oxidases 

 themselves are the peroxids. 



It must be remembered, moreover, that the liberation of 

 iodine from potassium iodit not only may be due to different 

 oxidizing influences but also that on the other hand, it is not a 

 specific property of all organic peroxids. Thus neither diethyl- 

 peroxid nor dibenzoylperoxid will liberate iodine, but benzoyl- 

 hydroperoxid can do so. But it is a very striking fact that 

 this peroxid can also liberate iodine from potassium iodit in the 

 presence of sodium bicarbonate, and not only in presence of 

 free acid. Such hydroperoxids as can liberate iodine are 

 exceedingly powerful Compounds 2 ), resembling hypochlorites in 

 their actions 3 ); hence the amount of such poisons in the cells 

 can only be exceedingly minute, otherwise the cells would be 

 killed. 



Since I have now preved that the iodine reaction does not 

 go parallel to the blue guaiac reaction and since further there 

 ■exists no proof that organic peroxids are the cause of the iodine 

 reaction in many vegetable objects, it was important to decide 

 the nature of the iodine liberating substance. Two suppositions 

 seemed worth while to be tested, either there might exist in 



x ) At least not of that kind that can liberate iodine. Also the 

 existence of zymogens of oxidases mihtates against the above hypothesis of 

 Kastle and Loewenhart. Becently, very interesting experiments were 

 described by Chodat and Bach (Ber. D. ehem. Ges. 1903, No. 3), from 

 which it appears that common oxidases are mixtures of „oxygenases" and 

 peroxidases. 



2 ) Compare, e. g. , Ber. d. D. ehem. Ges. 35, p. 3943 and p. 3946. 

 Becently, R. H. Page (Amer. pat. 717016 of 30. Dez. 1902) describet 

 acetylhydroperoxid 



CH 3 .C( 



which has a strong odor after hypochlorous acid and has a powerful bacte- 

 ricidal action. 



3 ) Compare in regard to the data here mentioned, the articles of 

 Bayer and Villiger in „Berichte der Deutschen chemischeu Gesellschaft", 

 1899 and 1900, especially in the latter volume, p. 1578. 



