97 



•■for the detection of the existence of a man" than is the balance for a 

 molecule, he would be obliged to go back and report the earth uninhabited. 

 In fact his instrument for the man test would need to be 26,600,000 times 

 as sensitive as the balance to give him even a hint of the probability of 

 an earth population. 



Thomson says that the smallest quantity of unelectrified matter ever 

 detected is probably neon, and this was discovered by the spectroscope — not 

 the balance. But the number of molecules of neon required to give a spec- 

 troscopic effect is about ten million million, or about 7,000 times the popu- 

 lation of the earth. It has been shown that the presence of a single 

 charged atom can be detected by electrical means. Thus the electroscope 

 is millions of millions of times as sensitive as the spectroscope, which is 

 itself in many cases far more sensitive than the balance. This explains, 

 in part, why radium was discovered by physicists, and why physicists 

 have been most active in all the work which has had to do with the theories 

 of electricity and matter. If chemists wish to compete with physicists in 

 this field of investigation they must adopt physical methods and apparatus 

 or devise some of their own which shall be far more sensitive than the 

 balance or spectroscope. Further, many of the great chemists of the world 

 need to awake to the fact that there is something doing and that they are 

 not doing it. Their indifference is surprising. Only three months ago one 

 of them expressed the following sentiments in a paper read before the 

 chemical section of the British Association. x * * * "Those who feel 

 that the electron is possibly" (note the possibly) "but a figment of the 

 imagination will remain satisfied with a symbolic system which has served 

 us so long and so well as a means of giving expression to facts which we 

 do not pretend to explain. * * * Until the credentials of the electron 

 are placed on a higher plane of practical politics, until they are placed on 

 a practical plane, we may well rest content with our present condition 

 and admit frankly that our knowledge is insufficient to enable us even to 

 venture on an explanation of valency.'' Think of it ! We, the chemists, 

 "remain content" in (his day when, as the Hon. A. J. Balfour has said, 

 the attempt to unify physical science and nature '-"excites feelings of the 

 mos! acute intellectual gratification. The satisfaction it gives is almost 



Scientific American Supplement. 63, No. 1761. P. 21", Oct. 2, 1909. 



-"Reflections Suggested by the New Theory of Matter." Presidential Address, British 

 Association for the advancement of .Science, 1901. Science. 20 No. 504, pp. 257-266, Aug. 

 26,1901. 



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