MODiERN VIEWS ON MATTER. 237 



the magnet, are easily obstructed ])y obstacles, and are sooner brought 

 to rest by collisions with air atoms. The lion. R. B. Strutt" was the 

 first to affirm that these nondetlectable rays are the positive ions 

 moving- in a stream from the radio-active )>()dy. 



Rutherford has shown that these emanations are slightly atfected 

 in a ver}^ powerful magnetic field, but in an opposite direction to 

 the negative electrons. They are therefore proved to be positively 

 charged bodies moving with great velocity. For the first time Ruther- 

 ford has measured their speed and mass, and he shows they are ions 

 of matter moving with a speed of the order of that of light. 



There is also a third kind of emanation produced Ijy radium. 

 Besides the highly penetrating rays deflected by a magnet, there are 

 very penetrating rays not at all afl'ected by magnetism. These accom- 

 pan}^ the previous emanations, and are Rcintgen rays — ether vibra- 

 tions — produced as secondary phenomena by the sudden arrest of 

 velocity of the electrons by solid matter, producing a series of Stoke- 

 sian "pulses'' or explosive ether waves shot into space. 



Many lines of argument and research tending toward the same point 

 give trustworthy data b}^ Avhich to calculate the masses and velocities 

 of these different particles. I must deal with big figures, l>ut big and 

 little are relative and are onl}" of importance in relation to the limita- 

 tions of our senses. I will take as the standard the atom of hydrogen 

 gas — the smallest material bod}^ hitherto recognized. The mass of an 

 electron is one seven-hundredths of an atom of h3'drogen, or 3 X 10~-^ 

 gram, according to J. J. Thomson, and its velocity is 2 X 10'' centi- 

 meters per second, or two-thirds that of light. The kinetic energy 

 per nnlligram is lo^'^ ergs, about 3,500,000 foot-tons. Becquerel has 

 calculated that 1 square centimeter of radio-active surface would radiate 

 into space 1 gram of mattei' in one billion years. 



The positively electrified masses or ions are enormously great in 

 comparison with the size of the electron. Sir Oliver Lodge illustrates 

 it thus: If we imagine an ordinary sized church to be an atom of 

 hydrogen, the electrons constituting it will be represented ])y about 

 7oO grains of sand, each the size of an ordinary- full stop (8.50 jjositive 

 and 3.50 negative), dashing in all directions inside, or, according to 

 Lord Kelvin, rotating with inconceivable velocity. Put in another 

 way; the sun's diameter is about 1.500,000 kilometers, and that of the 

 smallest planetoid al)out li-i kilometers. Tf an atom of hydrogen be 

 magnified to the size of the sun, an electron will be about two-thii'ds 

 the diameter of the planetoid. 



The extreme minuteness and S|)arsenessof the electrons in the atom 

 account for their penetration. While the nior(> massive ions are 

 stopped by intercollisions in ])assing among atoms, so that they are 



"Pliil. Trans. \i. S., A. IDOl, V..1. rXCVT, ],. r)25. 



