314 Lord Kelvin : An Attempt to 



crystal, until heat conducted and radiated in from the sur- 

 rounding matter compensates the cooling effect of the loadings, 

 and a permanent equilibrium of temperature is reached. 



§ 4. A certain definite proportion of all the loaded atoms, 

 probably a very small proportion, will, according to the 

 equilibrium of kinetic averages, become unloaded every second 

 of time. Electrions will be projected out of these atoms with 

 enormous velocities ; sufficient no doubt to shoot them through 

 the substance o£ the crystal into space outside. It will be 

 convenient for us to call this action a discharge, or explosion ; 

 just as the immediate result of igniting the cordite in a loaded 

 great gun is called a discharge, or explosion. The exciting- 

 cause of our supposed atomic explosion is a shaking of the 

 electrion from its stable equilibrium in the centre, far enough 

 out to get beyond the range of the stability, and to be expelled 

 away by repulsion. This repulsion increases to a very high 

 maximum, and thence diminishes to zero, and changes 

 continuously to the relatively small amount of the attraction 

 between the resinous electrion and the vitreous atom, 

 experienced when the electrion passes out of the atom. 



§ 5. Those of the discharges of loaded atoms which send 

 the electrion inwards, relatively to the crystal, would, by the 

 recoil, force the unloaded atom outwards : and, if it is near 

 enough to the surface of the crystal, would send it out into 

 the surrounding space, with comparatively small velocity 

 and energy. The unloaded atoms, being vitreously electric, 

 constitute the " a radiations/' when they are sent outside 

 the crystal by the force of the explosion. They would 

 generate comparatively little heat in being brought to rest by 

 the resistance of the matter outside the crystal. The 

 generation of heat by the electrions which are shot out, 

 would be much greater because of their much greater kinetic 

 energy. 



§ 6. It seems to me that it must be chiefly the electrions 

 (the " (3 particles ") which do the work of producing heat 

 at the rate of one hundred gram water centigrade calories, 

 per gram of Radium, per hour : but the " a particles " must 

 also contribute to it. 



§ 7. This process can go on forever, without violating the 

 law of conservation of energy, and without any monstrous y 

 or infinite, store of potential energy in the loaded Radium 

 atom. The shooting out of electrions with prodigious velo- 

 cities generates heat locally in the material around the Radium 

 crystal; while heat is taken into the crystal by conduction^ 

 and radiation, to supply the energy for the continued loadings 

 of unloaded Radium atoms. 



