| E₀ + E1 | E₀ – E1 | Alternations per second | ρ | K |
|---|---|---|---|---|
| 152 | 101 | 57 | ·27 | 1·25 |
| 225 | 150 | 57 | ·38 | 1·17 |
| 300 | 200 | 57 | ·44 | 1·24 |
Plates 2 cms. apart.
| E₀ + E1 | E₀ – E1 | Alternations per second | ρ | K |
|---|---|---|---|---|
| 273 | 207 | 44 | ·37 | 1·47 |
| 300 | 200 | 53 | ·286 | 1·45 |
The average mobility K deduced from a large number of experiments was 1·3 cms. per sec. per volt per cm. for atmospheric pressure and temperature. This velocity is about the same as the velocity of the positive ion produced by Röntgen rays in air, viz. 1·37 cms. per sec. The results obtained with the radium emanation were more uncertain than those for thorium on account of the distribution of some excited activity on the positive electrode. The values of the velocities of the carriers were however found to be roughly the same for radium as for thorium.
These results show that the carriers of the active deposit travel in the gas with about the same velocity as the positive or negative ions produced by the radiations in the gas. This indicates either that the active matter becomes attached to positive ions, or that the active matter itself, acquiring in some way a positive charge, collects a cluster of neutral molecules which travel with it.
192. Carriers of the excited activity from actinium and “emanium.” Giesel[[292]] observed that “emanium” gave off a large quantity of emanation, and that this emanation gave rise to a type of radiation which he termed the E rays. A narrow metal cylinder containing the active substance was placed with the open end downwards, about 5 cms. above the surface of a zinc sulphide screen. The screen was charged negatively to a high potential by an electric machine, and the cylinder connected with earth. A luminous spot of light was observed on the screen, which was brighter at the edge than at the centre. A conductor, connected with earth, brought near the luminous spot apparently repelled it. An insulator did not show such a marked effect. On removal of the active substance, the luminosity of the screen persisted for some time. This was probably due to the excited activity produced on the screen.
The results obtained by Giesel support the view that the carriers of excited activity of “emanium” have a positive charge. In a strong electric field the carriers travel along the lines of force to the cathode, and there cause excited activity on the screen. The movement of the luminous zone on the approach of a conductor is due to the disturbance of the electric field. Debierne[[293]] found that actinium also gave off a large amount of emanation, the activity of which decayed very rapidly with the time, falling to half value in 3·9 seconds.
This emanation produces excited activity on surrounding objects, and at diminished pressure the emanation produces a uniform distribution of excited activity in the enclosure containing the emanation. The excited activity falls to half value in 41 minutes.
Debierne observed that the distribution of excited activity was altered by a strong magnetic field. The experimental arrangement is shown in [Fig. 71A]. The active matter was placed at M, and two plates A and B were placed symmetrically with regard to the source. On the application of a strong magnetic field normal to the plane of the paper, the excited activity was unequally distributed between the plates A and B. The results showed that the carriers of excited activity were deviated by a magnetic field in the opposite sense to the cathode rays, i.e. the carriers were positively charged. In some cases, however, the opposite effect was obtained. Debierne considers that the excited activity of actinium is due to “ions activants,” the motion of which is altered by a magnetic field. Other experiments showed that the magnetic field acted on the “ions activants” and not on the emanation.
