Does Hydrogen Peroxide occur in Plants? 



BY 



J. Cho. 



It had been often stated that hydrogen peroxide in small 

 quantities occurs in plants, but it was shown by 77/. Bokorny {,) and 

 also by W. Pfeffer, {2) that these statements are not well founded. 

 Quite recently, however, it has again been asserted to do so by 

 A. Bach.™ After he had tried all known reagents and had found 

 them to be insufficient for proving the presence of very small 

 quantities of hydrogen peroxide in plants, he employed a new 

 reagent which, indeed, may prove useful in certain cases. 



This consists of a highly diluted mixture of potassium bi- 

 chromate with free aniline. 1+1 



The liquid to be tested has to be mixed with an equal 

 volume of this reagent, in presence of a little oxalic acid. If a 

 trace of hydrogen peroxide is present, a violet coloration is pro- 

 duced, due to the action upon aniline of perchromic acid, 

 intermediary formed. 



I have convinced myself of the delicacy of this interesting 

 reaction. Bach employed it in examining twenty-five species of 

 plants, of which eighteen yielded a positive result. He says, 



" Sur les vingt-cinq especes vegetales examinees, les 

 dix-huit suivantes ont donne un resultat positif en cc qui 

 concerne la presence de l'eau oxygenee : 



Brassica asperifolia, B. oleifeta, Daucus carota, Beta 

 vulgaris, Geranium rotundifolium, Hedera helix, Lauro- 

 cerasus, Aster, Tropceolum pentaphyllium, Chrysanthe- 

 mum Balsamita, Mericurialis annua, Urtica, Calla 

 palustris, Vicia fava, Papaver rhceas, Sisymbrium nastur- 



(1) Pringsheims Jahrb., vol. 17. 



(2) Ber. Sachs. Akad. Wiss., 1889. p. 493. 



(3) Comptes rendu*., t. CXIX., p. 286. 



(4) The solution contains in one liter 0.03 gr. potassium bichromate and 5 

 drops of aniline. In testing, one drop of a 5 "j a solution of oxalic acid is added for 

 5 cc. of the reagent. 



