THE MYSTERY OF MATTER. 191 



Professor Joly, of Dublin, suggests the startling hypothesis 

 that the radiiun emanation in the earth's atmosphere may be 

 directly derived from the sun. 



There is good reason to think that ordinary matter is to some 

 extent radio-active, and if so must be slowly though surely 

 undergoing change. Strutt says we have a million-fold descent 

 in radio-activity when passing from radium to uranium, and it 

 is at least possible that some ordinary substances may possess 

 an activity of their own, apart from radio-active impurities, 

 which is much more than a millionth part of that of uranimn. 

 Campbell claims to have obtained evidence that ordinary 

 matter possesses the property of emitting ionising radiations, 

 and that each element emits radiations differing both in 

 character and intensity. Rutherford says that if the expulsion 

 of an rt particle be taken as evidence of atomic disintegration, 

 calculation shows that the life of ordinary matter must be 

 regarded as at least one thousand times that of uranium. But 

 he also remarks that it is by no means necessary to suppose that 

 the transformation of matter should always be accompanied by 

 the intense effects exhibited by the radio-active bodies ; for 

 that ordinary matter might be emitting « particles at a rate 

 comparable to that of uranimn, but that if their speed was too 

 low to produce sensible ionisation it would be difl&cult to detect 

 their presence. 



M. Gustavo Le Bon, in an article published in the ' Athenaeum ' 

 of 17th November, 1906, says that all bodies possess the property 

 of radio-activity under certain conditions. He cites as an 

 example mercury, which is not appreciably radio-active in its 

 ordinary state, but he says that if a few millimetres of its weight 

 of tin be added to it, it becomes forty times more active than 

 uranium. In the same article he says that " all bodies contain 

 an immense reservoir of energy shut up within them from the 

 time of their formation." He thinks that the atoms of bodies 

 are of very different ages, and that the tendency of any atom to 

 disintegration is simply a consequence of old age. He considers 

 that the incandescence of the sun and stars and the greater 

 part of the forces of the universe are due to the liberation of the 

 intra-atomic energy which accompanies what he calls the 

 " dematerialisation of matter." Some of his conclusions are : 

 " Matter formerly supposed indestructible is slowly fading away 

 by the continual dissociation of the atoms of which it is 

 composed." " Energy and matter are two different forms of the 

 same thing. Matter represents a stable form of intra-atomic 



