PROBLEMS OF INORGANIC CHEMISTRY. 43 



as much energy as several hundred tons of nitroglycerine. The order 

 of the quantity of energy evolved during the disintegration of the atom 

 is as astonishing as the nature of the change. But the nature of the 

 change is parallel to what would take place if an extremely compli- 

 cated hydrocarbon were to disintegrate; its disruption into simpler 

 paraffins and defines would also be attended with loss of energy. We 

 may therefore take it, I think, that the disintegration hypothesis of 

 Eutherford and Soddy is the only one which will meet the case. 



If radium is continually disappearing, and would totally disappear 

 in a very few thousand years, it follows that it must be reproduced 

 from other substances, at an equal rate. The most evident conjecture, 

 that it is formed from uranium, has not been substantiated. Soddy 

 has shown that salts of uranium, freed from radium, and left for a 

 year, do not contain one ten-thousandth part of the radium that one 

 would expect to be formed in the time. It is evident therefore that 

 radium must owe its existence to the presence of some other substances, 

 but what they are is still unascertained. 



During the investigation of Rutherford and Soddy of the thorium 

 emanation, a most interesting fact was observed, namely, that precipi- 

 tation of the thorium as hydroxide by ammonia left unprecipitated a 

 substance, which they termed thorium-X, and which was itself highly 

 radio-active. Its radio-active life, however, was a short one; and as 

 it decayed, it was reproduced from its parent thorium at an equal rate. 

 Here is a case analogous to what was sought for with radium and 

 uranium; but evidently uranium is not the only parent of radium; 

 the operation is not one of parthenogenesis. Similar facts have been 

 elicited for uranium by Crookes. 



The a-rays, caused by the disintegration of radium and of its em- 

 anation, are accompanied by rays of quite a different character; they 

 are the /?-rays, identical with electrons, the mass of which has been 

 measured by J. J. Thomson and others. These particles are projected 

 with enormous velocity, and are capable of penetrating glass and metal 

 screens. The power of penetration appears to be proportional to the 

 amount of matter in the screen, estimated by its density. These elec- 

 trons are not matter; but, as I shall relate, they are capable of causing 

 profound changes in matter. 



For the past year, a solution of radium bromide has been kept in 

 three glass bulbs each connected to a Topler pump by means of capil- 

 lary tubing. To ensure these bulbs against accident, each was sur- 

 rounded by a small beaker; it happened that one of these beakers con- 

 sisted mainly of potash glass; the other two were of soda glass. The 

 potash-glass beaker became brown, while the two soda-glass beakers 

 became purple. I think there is every probability that the colors are 

 due to liberation of the metals potassium and sodium in the glass. 

 They are contained in that very viscous liquid, glass, in the colorless 

 ionic state; but these ions are discharged by the /?-rays, or negative 



