a history of science-1-第33章

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　germ　of　the　science　of　the　nineteenth…century　chemistry；　but　perhaps　the　germs　also　of　the　yet　undeveloped　chemistry　of　the　twentieth　century。　Yet　we　dare　suggest　that　in　their　enthusiasm　for　the　atomic　theory　of　Democritus　the　historians　of　our　generation　have　done　something　less　than　justice　to　that　philosopher's　precursor；　Anaxagoras。　And　one　suspects　that　the　mere　accident　of　a　name　has　been　instrumental　in　producing　this　result。　Democritus　called　his　primordial　element　an　atom；　Anaxagoras；　too；　conceived　a　primordial　element；　but　he　called　it　merely　a　seed　or　thing；　he　failed　to　christen　it　distinctively。　Modern　science　adopted　the　word　atom　and　gave　it　universal　vogue。　It　owed　a　debt　of　gratitude　to　Democritus　for　supplying　it　the　word；　but　it　somewhat　overpaid　the　debt　in　too　closely　linking　the　new　meaning　of　the　word　with　its　old　original　one。　For；　let　it　be　clearly　understood；　the　Daltonian　atom　is　not　precisely　comparable　with　the　atom　of　Democritus。　The　atom；　as　Democritus　conceived　it；　was　monistic；　all　atoms；　according　to　this　hypothesis；　are　of　the　same　substance；　one　atom　differs　from　another　merely　in　size　and　shape；　but　not　at　all　in　quality。　But　the　Daltonian　hypothesis　conceived；　and　nearly　all　the　experimental　efforts　of　the　nineteenth　century　seemed　to　prove；　that　there　are　numerous　classes　of　atoms；　each　differing　in　its　very　essence　from　the　others。　As　the　case　stands　to…day　the　chemist　deals　with　seventy…odd　substances；　which　he　calls　elements。　Each　one　of　these　substances　is；　as　he　conceives　it；　made　up　of　elementary　atoms　having　a　unique　personality；　each　differing　in　quality　from　all　the　others。　As　far　as　experiment　has　thus　far　safely　carried　us；　the　atom　of　gold　is　a　primordial　element　which　remains　an　atom　of　gold　and　nothing　else；　no　matter　with　what　other　atoms　it　is　associated。　So；　too；　of　the　atom　of　silver；　or　zinc；　or　sodiumin　short；　of　each　and　every　one　of　the　seventy…odd　elements。　There　are；　indeed；　as　we　shall　see；　experiments　that　suggest　the　dissolution　of　the　atomthat　suggest；　in　short；　that　the　Daltonian　atom　is　misnamed；　being　a　structure　that　may；　under　certain　conditions；　be　broken　asunder。　But　these　experiments　have；　as　yet；　the　warrant　rather　of　philosophy　than　of　pure　science；　and　to…day　we　demand　that　the　philosophy　of　science　shall　be　the　handmaid　of　experiment。　When　experiment　shall　have　demonstrated　that　the　Daltonian　atom　is　a　compound；　and　that　in　truth　there　is　but　a　single　true　atom；　which；　combining　with　its　fellows　perhaps　in　varying　numbers　and　in　different　special　relations；　produces　the　Daltonian　atoms；　then　the　philosophical　theory　of　monism　will　have　the　experimental　warrant　which　to…day　it　lacks；　then　we　shall　be　a　step　nearer　to　the　atom　of　Democritus　in　one　direction；　a　step　farther　away　in　the　other。　We　shall　be　nearer；　in　that　the　conception　of　Democritus　was；　in　a　sense；　monistic；　farther　away；　in　that　all　the　atoms　of　Democritus；　large　and　small　alike；　were　considered　as　permanently　fixed　in　size。　Democritus　postulated　all　his　atoms　as　of　the　same　substance；　differing　not　at　all　in　quality；　yet　he　was　obliged　to　conceive　that　the　varying　size　of　the　atoms　gave　to　them　varying　functions　which　amounted　to　qualitative　differences。　He　might　claim　for　his　largest　atom　the　same　quality　of　substance　as　for　his　smallest；　but　so　long　as　he　conceived　that　the　large　atoms；　when　adjusted　together　to　form　a　tangible　substance；　formed　a　substance　different　in　quality　from　the　substance　which　the　small　atoms　would　make　up　when　similarly　grouped；　this　concession　amounts　to　the　predication　of　difference　of　quality　between　the　atoms　themselves。　The　entire　question　reduces　itself　virtually　to　a　quibble　over　the　word　quality；　So　long　as　one　atom　conceived　to　be　primordial　and　indivisible　is　conceded　to　be　of　such　a　nature　as　necessarily　to　produce　a　different　impression　on　our　senses；　when　grouped　with　its　fellows；　from　the　impression　produced　by　other　atoms　when　similarly　grouped；　such　primordial　atoms　do　differ　among　themselves　in　precisely　the　same　way　for　all　practical　purposes　as　do　the　primordial　elements　of　Anaxagoras。　The　monistic　conception　towards　which　twentieth…　century　chemistry　seems　to　be　carrying　us　may　perhaps　show　that　all　the　so…called　atoms　are　compounded　of　a　single　element。　All　the　true　atoms　making　up　that　element　may　then　properly　be　said　to　have　the　same　quality；　but　none　the　less　will　it　remain　true　that　the　combinations　of　that　element　that　go　to　make　up　the　different　Daltonian　atoms　differ　from　one　another　in　quality　in　precisely　the　same　sense　in　which　such　tangible　substances　as　gold；　and　oxygen；　and　mercury；　and　diamonds　differ　from　one　another。　In　the　last　analysis　of　the　monistic　philosophy；　there　is　but　one　substance　and　one　quality　in　the　universe。　In　the　widest　view　of　that　philosophy；　gold　and　oxygen　and　mercury　and　diamonds　are　one　substance；　and；　if　you　please；　one　quality。　But　such　refinements　of　analysis　as　this　are　for　the　transcendental　philosopher；　and　not　for　the　scientist。　Whatever　the　allurement　of　such　reasoning；　we　must　for　the　purpose　of　science　let　words　have　a　specific　meaning；　nor　must　we　let　a　mere　word…jugglery　blind　us　to　the　evidence　of　facts。　That　was　the　rock　on　which　Greek　science　foundered；　it　is　the　rock　which　the　modern　helmsman　sometimes　finds　it　difficult　to　avoid。　And　if　we　mistake　not；　this　case　of　the　atom　of　Democritus　is　precisely　a　case　in　point。　Because　Democritus　said　that　his　atoms　did　not　differ　in　quality；　the　modern　philosopher　has　seen　in　his　theory　the　essentials　of　monism；　has　discovered　in　it　not　merely　a　forecast　of　the　chemistry　of　the　nineteenth　century；　but　a　forecast　of　the　hypothetical　chemistry　of　the　future。　And；　on　the　other　hand；　because　Anaxagoras　predicted　a　different　quality　for　his　primordial　elements；　the　philosopher　of　our　day　has　discredited　the　primordial　element　of　Anaxagoras。　Yet　if　our　analysis　does　not　lead　us　astray；　the　theory　of　Democritus　was　not　truly　monistic；　his　indestructible　atoms；　differing　from　one　another　in　size　and　shape；　utterly　incapable　of　being　changed　from　the　form　which　they　had　maintained　from　the　beginning；　were　in　reality　as　truly　and　primordially　different　as　are　the　primordial　elements　of　Anaxagoras。　In　other　words；　the　atom　of　Democritus　is　nothing　less　than　the　primordial　seed　of　Anaxagoras；　a　little　more　tangibly　visualized　and　given　a　distinctive　name。　Anaxagoras　explicitly　conceived　his　elements　as　invisibly　small；　as　infinite　in　number；　and　as　made　up　of　an　indefinite　number　of　kindsone　for　each　distinctive　substance　in　the　world。　But　precisely　the　same　postulates　are　made　of　the　atom　of　Democritus。　These　also　are　invisibly　small；　these　also　are　infinite　in　number；　these　also　are　made　up　of　an　indefinite　number　of　kinds；　corresponding　with　the　observed　difference　of　substances　in　the　world。　〃Primitive　seeds；〃　or　〃atoms；〃　were　alike　conceived　to　be　primordial；　un…　changeable；　and　indestructible。　Wherein　then　lies　the　difference？　We　answer；　chiefly　in　a　name；　almost　solely　in　the　fact　that　Anaxagoras　did　not　attempt　to　postulate　the　physical　properties　of　the　elements　beyond　stating　that　each　has　a　distinctive　personality；　while　Democritus　did　attempt　to　postulate　these　properties。　He；　too；　admitted　that　each　kind　of　element　has　its　distinctive　personality；　and　he　attempted　to　visualize　and　describe　the　characteristics　of　the　personality。　Thus　while　Anaxagoras　tells　us　nothing　of　his　elements　except　that　they　differ　from　one　another；　Democritus　postulates　a　difference　in　size；　imagines　some　elements　as　heavier　and　some　as　lighter；　and　conceives　even　that　the　elements　may　be　provided　with　projecting　hooks；　with　the　aid　of　which　they　link　themselves　one　with　another。　No　one　to…day　takes　these　crude　visualizings　seriously　as　to　their　details。　The　sole　element　of　truth　which　these　dreamings　contain；　as　distinguishing　them　from　the　dreamings　of　Anaxagoras；　is　in　the　conception　that　the　various　atoms　differ　in　size　and　weight。　Here；　indeed；　is　a　vague　fore…shadowing　of　that　chemistry　of　form　which　began　to　come　into　prominence　towards　the　close　of　the　nineteenth　century。　To　have　forecast　even　dimly　this　newest　phase　of　chemical　knowledge；　across　the　abyss　o