of 
“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 electrosecope 
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. * * * “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 this day when, as the Hon. A. J. Balfour has said, 
the attempt to unify physical science and nature *“excites feelings of the 
most acute intellectual gratification. The satisfaction it gives is almost 
1Scientific American Supplement. 63, No. 1761. P. 21%, Oct. 2, 1909. 
2“Reflections Suggested by the New Theory of Matter.’’ Presidential Address, British 
Association for the advancement of Science, 190!. Science. 20 No. 504, pp. 257-266, Aug. 
26, 1904. 
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