120 BIOGRAPHIES OF SCIENTIFIC MEN 



and Kelvin came to the conclusion that the distance 

 between the centres of contiguous molecules is less than 

 the one-five-millionth and greater than one-thousand- 

 millionth of a centimetre. 



All this work has been the outcome of Dalton's 

 atomic theory. Sir George Darwin says that " within 

 the last few years the electrical researches of Lenard, 

 Rontgen, Becquerel, the Curies, Larmor, Thomson, and 

 a host of others have shown that the atom is not in- 

 divisible (as Dalton assumed), and a flood of light has 

 been thrown thereby on the ultimate constitution of 

 matter. Among all these fertile investigators it seems 

 that J. J. Thomson stands pre-eminent, because it is 

 practically through him that we are to-day in a better 

 position for picturing the structure of an atom than 

 was ever the case before. It has been shown that the 

 atom really consists of large numbers of component parts. 

 By various converging lines of experiment it has been 

 proved that the simplest of all atoms, namely, hydrogen 

 consists of about three hundred separate parts ; while 

 the number of parts in the atom of the denser metals 

 must be counted by tens of thousands. These separate 

 parts of the atom have been called corpuscles or electrons, 

 and may be described as particles of negative electricity." 



As Professor Rutherford says : " It is not true that the 

 discoveries of the last ten years had weakened the atomic 

 theory. On the contrary, they had enormously strength- 



