Manchester Memoirs, Vol. xlviii. (1904), No. 8. 23 



quantity that the detection of the charge carried would be 

 an experimental impossibility. This is the case with the 

 negative ion when under the conditions stated it becomes 

 a cathode-ray particle. In the disintegration of the 

 metabolons we have ions, or positively and negatively 

 charged particles, shot out as rays spontaneously with 

 speeds far exceeding any that can be produced by the 

 action of electrical forces, and as we have seen, we have 

 arrived at such a point of refinement, that it would seem 

 that further advance must be stopped by our reaching the 

 limit of the subdivision of matter. But deprive an ion of 

 its charge, the radiant particle of its kinetic energy, or the 

 metabolon of its power to further disintegrate, and they 

 pass at once beyond our ken. The matter remains, but 

 the energy is lost, and we must fall back upon direct 

 methods, the use of the spectroscope, or the employment 

 of chemical tests, and these even if they were a billion 

 times more sensitive than they are would by no means 

 suffice for the purpose. 



This difficulty attended the important question as to 

 what are the ultimate products remaining when the 

 successive distintegrations of a radio-element have 

 run their course, and the matter has again reached a 

 stable state. There are two ways in which the 

 problem may be approached. Either the time over 

 which the products of the disintegration are allowed 

 to accumulate may be sufficiently extended, or the 

 quantity of material employed may be correspondingly 

 increased. The first method was the more immediately 

 applicable. For in the natural minerals which contain 

 the radio-elements it must be supposed that the products 

 of the disintegration have been steadily accumulating 

 throughout past ages, and should be present in sufficient 

 quantity to be detected by ordinary means. This led 



