1. Many measurements were made with the two systems
H2/NaOH C/NaOH C + x gm. gelatin/H2
H2/NaOH C/KCl (sat.)/NaOH C + x gm. gelatin/H2
in which x was varied from zero to more than enough for complete combination.
2. From these measurements the change in boundary potential with quantity of gelatin present was determined.
3. The boundary potentials were calculated by means of a modified form of the Henderson equation.
4. The results indicate that the mobility of the gelatinate ion is about 20.