200 BIOGRAPHIES OF SCIENTIFIC MEN 



and the motion of these electrons, under the influence of 

 electrostatic force, must contribute to the electric con- 

 ductivity of the gas ; must, in fact, constitute all of it 

 which was not due to transport of atoms of the gas 

 carrying less than the neutralizing quantum of electrons. 

 Thus every substance must possess radio-activity, 1 said 

 Lord Kelvin. Some interesting remarks would be found 

 in the Philosophical Magazine, where it was pointed out 

 that radium was three hundred million times more active 

 than the most active common material yet experimented 

 with. 



How was this enormous radio-activity of radium to 

 be accounted for ? Lord Kelvin suggested that it might 

 be because it was exceedingly polyelectronic ; that the 

 saturating quantum of electrons in an atom of radium 

 might be hundreds or thousands or millions of times as 

 many as those of atoms of ordinary material. But this 

 left the mystery of radium untouched Curie's discovery 

 that it perpetually emitted heat at a rate of about 90 

 Centigrade calories per gramme per hour. If emission of 

 heat at this rate went on for little more than a year, or, 

 say, ten thousand hours, there was as much heat as would 

 raise the temperature of 900,000 grammes of water 1 C. 

 It seemed to Lord Kelvin utterly impossible that this 



1 Even the pigment of Micrococcus glutinis is radio-active ; and also 

 the chromoplastids of Helianthus, Verbena, and Geranium. (See 

 A. B. Griffiths' papers in Chemical News, vol. xci. p. 97 ; Berichte der 

 deutschen chemischen Geselhchaft, vol. xxxvi., p. 3959.) 



