NEW CONCEPTIONS IN SCIENCE 



ments, arriving at the identical result by quite 

 different means that men of science have been 

 willing to acknowledge their value. They were 

 revolutionary, for they indicate the existence of 

 particles of matter countable, weighable, meas- 

 urable quantities of matter a thousand times 

 smaller than the smallest known atom. 



At first sight this seemed incredible. The mighty 

 atom, if one may borrow a phrase, is the present 

 basis of the whole science of chemistry, and in 

 part of physics as well, both sciences of a mar- 

 vellous development. An immense amount of in- 

 direct evidence has been dug out and built up in 

 the long toil of the century, which can only be 

 neatly joined or vividly pictured by the supposition 

 that the atom is an ultimate reality. There is, 

 indeed, no other explanation in the field. So many 

 and such different kinds of researches have tended 

 to confirm the idea of the atom as the smallest ex- 

 isting particle of matter, that the notion of chop- 

 ping up this atom, in turn, was a little too much 

 for many. 



I have here spoken of the atom as though there 

 were only one kind ; but, as we have seen, modern 

 chemistry has been built up on the notion that 

 there are as many different kinds of atoms as there 

 are different elements or kinds of matter. They 

 range in weight from that of hydrogen, the lightest, 



158 



