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 Th. 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. 1 2 (3) 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. (4) 
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 espèces végétales examinées, les 
dix-huit suivantes ont donné un résultat positif en ce qui 
concerne la présence de l’eau oxygénée : 
Brassica asperifolia, B. oleifera, Daucus carota, Beta 
vulgaris, Geranium rotundifolium, Hedera helix, Lauro- 
cerasus, Aster, Tropœolum pentaphyllium, Chrysanthe¬ 
mum Balsamita, Mericurialis annua, Urtica, Calla 
palustris, Vicia fava, Papaver rhoeas, Sisymbrium nastur- 
(1) Pringsheims Jahrb., vol. 17. 
(2) Ber. Sachs. Akad. Wiss., 188g. p. 493. 
(3) Comptes rendus., t. CXIX., p. 286. 
(4) T h e solution contains in one liter 0.03 gr. potassium bichromate and 5 
drops of aniline. In testing, one drop of a 5 °/ 0 solution of oxalic acid is added for 
5 cc. of the reagent. 
