
The Emanation given off by Radium. DDO 
wax exhibited a behaviour in every way similar to the sub- 
stances already mentioned, but the modelling-clay acted 
quite differently. When subjected toa given torque it moved 
slowly up to a given position and stopped there. On removing 
the stress, it made an immediate partial recovery to a point 
where it permanently remained. 
The following list contains the results obtained with the 
several substances experimented with. 



Substance. | Temperature. Coefficient of 





| 
| Viscosity. 
12) w, 
Sit Siete a ae | 0 ee 
= wee ene 8 |) 9 B95e1010 | 
ee eee 15 b. b3x 1010 
Glass (Soda) ............ | 575 PP ee TOL 
ae ie Rh) 4 20 | 660 fils PDasc OEY 
or : 710 a STON, 
| Sodium stearate ...... 8 | 50x 10U 
| Shoemaker’s wax ...... | 8 | 4-7 x 106 | 


XLII. On the Emanation given off by Radium. By J. A. 
McCuievuandD, M.A., Professor of Experimental Physics, 
University College, Dublin*. 
TPXHE @ rays of radium have been proved to consist of 
positively charged particles moving with great velocity, 
the mass of the particle being comparable with that of the 
hydrogen atom. The 8 rays have also been shown to consist 
of charged particles moving with great velocity, the charge 
in this case being negative, and the mass of the particles very 
small compared with that of even the hydrogen atom. 
Little is known as yet about the y rays, except that they 
have very great penetrating power. 
The emanation produced by radium has been much studied, 
and many of its properties are known ; but it does not appear 
to have been definitely settled whether or not the emanation 
particles are charged ; and it is important to be certain on 
this point when framing a conception of the manner in which 
the radium atom disintegrates. The object in this paper is to 
test as accurately as possible whether or not the emanation 
carries an electric charge. Rutherford’s work indicates that 
it is not charged; but I have thought it advisable to make a 
* From an advance proof of the ‘Transactions of the Royal Dublin 
Society,’ n. s., vol. vill. part vi. pp. 89-94, communicated by the Author. 

