January 15, 1904.] 



SCIENCE. 



ing within the same road are often quite 

 unable to keep pace with its fleet movements 

 and would fain retire from the unequal 

 contest. It is not surprising, then, that 

 those actually contributing to the advance- 

 ment of science, pressing eagerly upward 

 and onward, should neglect to look back 

 upon the labors of those who precede them 

 and should sometimes lose sight of the obli- 

 gations which science owes to forgotten gen- 

 erations. "* His numerous contributions to 

 and intimate knowledge of the history of 

 chemistry, his gentle and generous sym- 

 pathy aided and stimulated many active in 

 research or technical applications of chem- 

 istry. His monumental bibliographies put 

 out by the Smithsonian Institution are mas- 

 terpieces. The grief and keen regret of his 

 loss are not confined to one nation. 



On another occasion it has been the good 

 fortune of him who has the honor of ad- 

 dressing you to-day to indicate that events 

 of literary moment, governmental modifica- 

 tions, inventions and forward stridings in 

 science, have apparently accommodated 

 themselves to historical periods during the 

 past century, f Striking, novel facts and 

 fancies, gleaned in the realm of inorganic 

 chemistry, have crested not a few of the 

 high waves of those human tides that beat 

 against the coasts of the untried and un- 

 known. 



The human mind knows by contrasts. 

 For the day we have night; for the good 

 there is evil. Where man would have a 

 God, he also had a devil ; for the true there 

 is the false; the verified and unverified. 

 The false may be true through ignorance; 

 the true may be false in the light of new 

 knowledge. Or, as Hegel put it, ' Sein und 

 das nieht Sein sind das Namliche. ' 



* ' Notes on the Early Literature of Chemistry — 

 The Book of the Balance of Wisdom,' New York 

 Academy of Sciences, May 29, 1876. 



t ' The Rare Earth Crusade; What it Portends, 

 Scientifically and Technically,' Science, N. S., 

 XVII., 722-781. 



Is matter continuous or discrete 1 argued 

 the opposed schools of Grecian philosophy 

 led by Leucippus, Democritus and Epicurus 

 and dominated by Aristotle. Despite the 

 clarity of the statements of the Roman 

 Lucretius,* the atomic hypothesis received 

 scant attention until the seventeenth cen- 

 tury of the Chinstian era, when Galileo's 

 experimental science assailed Aristotelian 

 metaphysics and demanded verification of 

 the premises of that philosophy which had 

 governed all the schools of Europe for two 

 thousand years, f "V^liile Gassendi, Boyle, 

 Descartes, Newton, xDcrhaps Boscovieh, 

 Lavoisier, Swedeborg, Richter, Fischer and 

 Higgins had to do Avith our modern atomic 

 theory, Dalton one hundred years ago 'cre- 

 ated a working tool of extraordinary power 

 and usefulness' in the laws of definite and 

 multiple proportions. As ClarkeJ re- 

 marked, 'Between the atom of Lucretius 

 and the Daltonian atom the kinship is 

 very remote.' Although the lineage is di- 

 rect, the work of Berzelius, Gmelin and 

 others; the laws of Faraday, Guy Lussac, 

 Avagadro, Dulong and Petit ; the reforma- 

 tions of Laurent and Gerhardt, but par- 

 ticularly Cannizzaro; the systematizations 

 of de Chancourtois, Newlands, Hinrichs, 

 Mendelejeff and Lothar Meyer; the stereo- 

 chemistry of van't Hoff and LeBel have 

 imperialized the ideas of the Manchester 

 philosopher, so that the conceptions of the 

 conservative atomists of to-day are quite 

 different from those at the beginning of the 

 closed century. § 



* " Nature reserving these as seeds of things 

 Permits in them no minish nor decay; 

 They can't be fewer and they can't be less." 

 Again, of compounds — 

 " Decay of some leaves others free to grow 

 And thus the sum of things rests unim- 

 paired." Book II., 79. 

 t See ' The Atomic Theory,' the Wilde Lecture 

 by F. W. Clarke at Dalton Celebration, May, 1903. 

 t Loc. cit. 



I While I have examined mucli of the original 

 literature, VenaWe's ' History of the Periodic 



