CHEMISTRY 87 



By comparing this small measure with the average total 

 distance which the molecule travels in a second, about 460 

 meters, it is found that the path pursued by the molecule 

 within one second is a zigzag course, divided on the average 

 into 6,000,000,000 little straight free paths between its en- 

 counters. 



Taking the average number of free paths, their average 

 duration has been e ooo ooo ooo ^^ ^ second. This duration, 

 however, is long compared with the smaller periodic times of 

 the alternating event we call light. When this is done it is 

 found that, while a molecule in the air has been travelling be- 

 tween one encounter and the next, 60,000 double vibrations of 

 red light and twice that number of the extreme violet ray have 

 on the average taken place ; and as all motions within a mole- 

 cule which give rise to spectral rays must lie between those 

 limits we are forced to admit either that an immense number 

 of orbital motions have been on the average executed within 

 the molecule during each of its flights or else that periodic 

 motion of some kind, of so complex a kind, has been going 

 on that when resolved it furnishes that immense number of 

 constituent motions. 



The foregoing speculations and conclusions were con- 

 sistent with a molecule composed of indivisible, indestructible 

 atoms. A different line of research starting with matter in 

 what Sir William Crookes calls the "radiant," an electrified 

 state, leads to the conclusion that the atom is a structure. The 

 atom instead of being a mass of matter, a mass of something 

 which entirely fills the space it seems to fill, is a more or less 

 complex structure of smaller units — negatively electrified units, 

 "electrons" or "corpuscles", along with a positive or perhaps 

 many positive unit electric charges. 



The atom like the molecule possesses structure, and while 

 the molecules are travelling about subtile events are all the 

 time going on within each of them, involving rapidly alter- 



