That mercury drops show a similar behavior was somewhat imperfectly shown in the original observations which I published on mercury.[130] I have since fully confirmed the conclusions there reached. That mercury drops can with suitable precautions be made to behave practically as [Pg 178] consistently as oil is shown in Fig. 13 (III), which represents data obtained by blowing into the observing chamber above the pinhole in the upper plate a cloud of mercury droplets formed by the condensation of the vapor arising from boiling mercury. These results have been obtained in the Ryerson Laboratory with my apparatus by Mr. John B. Derieux. Since the pressure was here always atmospheric, the drops progress in the order of size from left to right, the largest having a diameter about three times that of the smallest, the radius of which is .00003244 cm. The original data may be found in the Physical Review, December, 1916. In Fig. 13 (IV) is found precisely similar data taken with my apparatus by Dr. J. Y. Lee on solid spheres of shellac falling in air.[131] Further, very beautiful work, of this same sort, also done with my apparatus, has recently been published by Dr. Yoshio Ishida (Phys. Rev., May, 1923), who, using many different gases, obtains a group of lines like those shown in Fig. 13, all of which though of different slopes, converge upon one and the same value of “”, namely, . Fig. 13 [Pg 179] These results establish with absolute conclusiveness the correctness of the assertion that the apparent value of the electron is not in general a function of the gas in which the particle falls, of the materials used, or of the radius of the drop on which it is caught, even when that drop is of mercury, and even when it is as small as some of those with which Dr. Ehrenhaft obtained his erratic results. [Pg 180] If it appears to be so with his drops, the cause cannot possibly be found in actual fluctuations in the charge of the electron without denying completely the validity of my results. But these results have now been checked, in their essential aspects, by scores of observers, including Dr. Ehrenhaft himself. Furthermore, it is not my results alone with which Dr. Ehrenhaft’s contention clashes. The latter is at variance also with all experiments like those of Rutherford and Geiger and Regener on the measurement of the charges carried by - and -particles, for these are infinitely smaller than any particles used by Dr. Ehrenhaft; and if, as he contends, the value of the unit out of which a charge is built up is smaller and smaller the smaller the capacity of the body on which it is found, then these -particle charges ought to be extraordinarily minute in comparison with the charges on our oil drops. Instead of this, the charge on the -particle comes out exactly twice the charge which I measure in my oil-drop experiments.