Electric Potential of Solutions as a Cause of the Formation of Liesegang Rings

Abstract

FOLLOWING our experiments in relation to the influence of electric current on the formation of Liesegang rings, it has been found that silver nitrate (diluted) drops on chromogelatine cause a potential difference of nearly 80 millivolts. The silver nitrate has a positive, and the chromogelatine a negative, potential. This potential difference lasts only so long as silver dichromate is being formed. At first it decreases very quickly, and at the same time with the quick appearance of the rings; later, the rate of decrease becomes slower, parallel with the slower formation of the rings. If the silver nitrate–chromo-gelatine pair is short-circuited (by short-circuiting the electrodes), then a change is observed in the appearance of the Liesegang rings; normal rings are shown in Fig. 1 and modified rings in Figs. 2 and 3.