October 23, 1903.] 



SCIENCE. 



525 



l)i'gin. The atomic theory connects all of 

 these data together, and gives the mind a 

 simple reason for tlie relations which are 

 observed. We can not be satisfied with 

 mere equations; our thought will seek for 

 that whicli lies behind them ; and so the 

 anti-theorist fails to accomplish his pur- 

 pose because he leaves the human mind out 

 of account. The reasoning instrument has 

 its own laws and requirements, and they, 

 as well as the empirical observations of 

 science, must be satisfied. Even in as- 

 tronomy the law of gravitation is not 

 enough; men are continually striving to 

 ascertain its cause ; and no number of fail- 

 ures can prevent them from trying again 

 and yet again to penetrate into the heart 

 of the mystery. In the atomic theory the 

 same tendency is at work, and the very 

 nature of the atom itself, that thing which 

 we can neither see nor handle, has become 

 a legitimate subject for our questionings. 

 Shall we, having gone so far, assume that 

 we can go no farther ? 



'All roads lead to Rome.' If we accept 

 the atomic theory, we sooner or later find 

 ourselves speculating about the reality of 

 the atom, and at last we come face to face 

 with the old, old problem of the unity or 

 diversity of matter. We can, if we choose, 

 employ the theory as a working tool only, 

 and shut our ears to these profounder ques- 

 tions ; but it is not easy to do so. What is 

 the chemical atom? Is all matter iilti- 

 mately one substance? We may be un- 

 able to solve either problem, and yet we 

 can examine the evidence and see which 

 way it points. 



I think that all philosophical chemists 

 are now of the belief that the elements are 

 not absolutely distinct and .separate enti- 

 ties. In favor of their elementary nature 

 we have only negative evidence, the mere 

 fact that with our present resources we are 

 unable to decompose them into simpler 



forms. On that side of the argument there 

 is nothing more. On the other hand, we 

 see that the elements are bound together by 

 the most intimate relations, so much so 

 that unknown elements can be accurately 

 described in advance of their discovery, and 

 facts like these call for an explanation. 

 Something belonging to the elements in 

 common seems to underlie them all. If, 

 however, we study the atomic weights, we 

 are forced to observe that the elements do 

 not shade into one another continuously, 

 but that they vary by leaps which are some- 

 times relatively large, and sometimes quite 

 small. To Mendeleeff this irregular dis- 

 continuity is an argument against the 

 unity of matter, or, rather, an indication 

 that the periodic law lends no support to 

 the belief; but such a conclusion is un- 

 necessary. If the fundamental matter, the 

 'protyle,' as Crookes has called it, is itself 

 discontinuous and atomic in structure, the 

 same property must be shown in all of its 

 aggregations, and so the difficulties seen by 

 Mendeleeff disappear. The chemical 

 atoms become clusters of smaller particles, 

 whose relative magnitudes are as yet un- 

 known. 



That bodies smaller than atoms realiy 

 e.xist is the conclusion reached by J. J. 

 Thomson* from his researches upon the 

 ionization of gases. According to him, 

 this phenomenon 'consists in the detach- 

 ment from the atom of a negative ion,' this 

 being 'the same for all gases.' He regards 

 'the atom as containing a large number of 

 smaller bodies,' which he calls 'corpuscles," 

 and these are equal to one another. "In 

 the normal atom this a-ssemblage of cor- 

 puscles forms a system which is electrically 

 neutral." It must be borne in mind that 

 tliesp conclusions are drawn by Thomson 

 from the study of one class of phenomena, 



'Phil. Hag. (5), 48, p. 547. Also Popular 

 Science Monthly, August, 1901. 



