A Contribution to the Theory of Thixotropy

Although a careful review of literature has revealed that the phenomenon now termed “thixotropy” had already been observed some years ago by various research workers, the first systematic study of this phenomenon is of comparatively recent date as well as the denomination, which is taken from the Greek works, “ϑιξομαι” = “by touching” and “τζ′εωπω” = “to change,” and which gives a rather accurate conception as to what this phenomenon refers. For example, it has been found that certain colloids present in the form of a plastic gel can be spontaneously and adiabatically liquefied by simple mechanical influence, e. g., shaking, and that such liquefied gels, now being in the sol condition, will, if left quiet, return to the original plastic solid gel. This sol‐gel‐transformation can be repeated consecutively many times without changes in setting time, if all conditions are kept constant during the experiments.