Otober 23, 1903.] 



SCIENCE. 



517 



coinbiuiiii; luimber. the relative weight of 

 its atom, could be assigned. Prom this, the 

 law of defiiiitt' jiroportions logically fol- 

 lowed, for fractions of atoms were inadmis- 

 sible; and the law of multiple proportions. 

 which Daltoii worked out experimentally, 

 completed the generalization. The concep- 

 tion that all combination must take place 

 in tixed proportions was not new, and, in- 

 deed, despite the objections of Berthollet, 

 was generally assumed; but the atomic 

 theory gave a reason for the law and made 

 it intelligible. The idea of multiple propor- 

 tions had also occurred, although incom- 

 pletely, to others; but the detennination 

 of atomic weights was altogether original 

 and novel. The new atomic theory, which 

 tigui-ed chemical union as a .juxtaposition 

 of atoms, coordinated all of these rclatiims. 

 and gave to chemistry, for the first time, 

 an absolutely general quantitative basis. 

 The tables of Richter and Fischer, who 

 preceded Daltou, dealt only with special 

 ca-ses of combination, but they established 

 regularities which rendered easier the ac- 

 ceptance of the new and broader teachings. 

 The earlier atomic speculations were all 

 purely qualitative, and incapable of exact 

 application to specific problems: Daltou 

 created a working tool of extraordinary 

 power and usefulness. Between the atom 

 of Lucretius and the Daltonian atom the 

 kinship is very remote. 



Daltou was not a learned man. in the 

 s<Mise of mere erudition, but perhaps his 

 limitations did him no harm. Too much 

 learning is sometimes in the way, and clogs 

 the flight of that imagination by which the 

 greatest discoveries are made. The man 

 who could not see the forest because of the 

 trees was a good type of that scholarship 

 which never rises above petty details. It 

 may compile cneyelopsdias, l)ut it can not 

 generalize. In some ways, doubtless. Dal- 

 ton was narrow, and he failed to recognize 



the improvements which other men soon 

 introduced into his system. The chemical 

 symbols which he proposed were soon sup- 

 lilanted by the better formulaj invented by 

 Berzelius, and his views upon the densities 

 of gases were set aside by the more exact 

 woi-k of Gay Lussac, which Dalton never 

 fully appreciated. As an experimenter he 

 was crude, and excelled by several of his 

 contemporaries; his tables of atomic 

 weights, or rather equivalents, were only 

 rough approximations to the true values. 

 These defects, however, are only spots upon 

 the sun, and in no wise diminish his glory. 

 Dalton transformed an art into science, 

 and his influence upon chemistrj' was never 

 greater than it is to-day. The truth of 

 this statement will appear when we trace, 

 step by step, the development of chemical 

 doctrine. The guidiug clue, from first to 

 last, is Dalton 's atomic theory. 



Although Daltou first announced his 

 theory iu 1803. the publication of his 'Sys- 

 tem' in 1808 mai-ks the culmination of his 

 labors. The memorable controversy be- 

 tween Proust and Berthollet had by this 

 time exhavisted its force, and nearly all 

 chemists were satisfied that the law of def- 

 inite or constant proportions must be true. 

 The idea of multiple proportions was also 

 easily accepted; and as for the combining 

 numbers, they, after various revisions, came 

 generally into use. The atomic conception, 

 however, made its way more slowly, for 

 the fear of metaphysics still governed 

 many acute minds. Davy especially was 

 late in yielding to it, but in time even his 

 conversion was effected. Thomson, as we 

 have already noted, was the earliest and 

 most enthusiastic disciple of the new sys- 

 tem, and WoUaston. although cautiously 

 preferring the term 'equivalent' to that of 

 atomic weight, made useful contributions 

 to the theorv. These names mark the 



