The electrical resistivity of insulating materials

F. M. Clark: With regard to Dr. Curtis´ paper, I do want to emphasize the type of conduction which he calls colloidal conduction. I think that this is a type which we will have to recognize and consider in more detail than we have. When you consider that almost all of our insulations are colloidal in nature if not true colloids, you can see the significance of that type of conduction. I recognize that colloidal conduction is similar in many respects to electrolytic conduction. However, it owes its origin to larger charged masses and may occur in mediums where electrolytic conduction would be least expected.