a history of science-4-第1节

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A　History　of　Science；　Volume　4

by　Henry　Smith　Williams；　M。D。；　LL。D。

ASSISTED　BY　EDWARD　H。　WILLIAMS；　M。D。

IN　FIVE　VOLUMES　VOLUME　IV。

MODERN　DEVELOPMENT　OF　THE　CHEMICAL　AND　BIOLOGICAL　SCIENCES




A　HISTORY　OF　SCIENCE

BOOK　IV

MODERN　DEVELOPMENT　OF　THE　CHEMICAL　AND　BIOLOGICAL　SCIENCES

AS　regards　chronology；　the　epoch　covered　in　the　present　volume　is　identical　with　that　viewed　in　the　preceding　one。　But　now　as　regards　subject　matter　we　pass　on　to　those　diverse　phases　of　the　physical　world　which　are　the　field　of　the　chemist；　and　to　those　yet　more　intricate　processes　which　have　to　do　with　living　organisms。　　So　radical　are　the　changes　here　that　we　seem　to　be　entering　new　worlds；　and　yet；　here　as　before；　there　are　intimations　of　the　new　discoveries　away　back　in　the　Greek　days。　The　solution　of　the　problem　of　respiration　will　remind　us　that　Anaxagoras　half　guessed　the　secret；　and　in　those　diversified　studies　which　tell　us　of　the　Daltonian　atom　in　its　wonderful　transmutations；　we　shall　be　reminded　again　of　the　Clazomenian　philosopher　and　his　successor　Democritus。

Yet　we　should　press　the　analogy　much　too　far　were　we　to　intimate　that　the　Greek　of　the　elder　day　or　any　thinker　of　a　more　recent　period　had　penetrated；　even　in　the　vaguest　way；　all　of　the　mysteries　that　the　nineteenth　century　has　revealed　in　the　fields　of　chemistry　and　biology。　　At　the　very　most　the　insight　of　those　great　Greeks　and　of　the　wonderful　seventeenth…century　philosophers　who　so　often　seemed　on　the　verge　of　our　later　discoveries　did　no　more　than　vaguely　anticipate　their　successors　of　this　later　century。　To　gain　an　accurate；　really　specific　knowledge　of　the　properties　of　elementary　bodies　was　reserved　for　the　chemists　of　a　recent　epoch。　The　vague　Greek　questionings　as　to　organic　evolution　were　world…wide　from　the　precise　inductions　of　a　Darwin。　　If　the　mediaeval　Arabian　endeavored　to　dull　the　knife　of　the　surgeon　with　the　use　of　drugs；　his　results　hardly　merit　to　be　termed　even　an　anticipation　of　modern　anaesthesia。　And　when　we　speak　of　preventive　medicineof　bacteriology　in　all　its　phaseswe　have　to　do　with　a　marvellous　field　of　which　no　previous　generation　of　men　had　even　the　slightest　inkling。

All　in　all；　then；　those　that　lie　before　us　are　perhaps　the　most　wonderful　and　the　most　fascinating　of　all　the　fields　of　science。　As　the　chapters　of　the　preceding　book　carried　us　out　into　a　macrocosm　of　inconceivable　magnitude；　our　present　studies　are　to　reveal　a　microcosm　of　equally　inconceivable　smallness。　As　the　studies　of　the　physicist　attempted　to　reveal　the　very　nature　of　matter　and　of　energy；　we　have　now　to　seek　the　solution　of　the　yet　more　inscrutable　problems　of　life　and　of　mind。



I。　THE　PHLOGISTON　THEORY　IN　CHEMISTRY

The　development　of　the　science　of　chemistry　from　the　〃science〃　of　alchemy　is　a　striking　example　of　the　complete　revolution　in　the　attitude　of　observers　in　the　field　of　science。　As　has　been　pointed　out　in　a　preceding　chapter；　the　alchemist；　having　a　preconceived　idea　of　how　things　should　be；　made　all　his　experiments　to　prove　his　preconceived　theory；　while　the　chemist　reverses　this　attitude　of　mind　and　bases　his　conceptions　on　the　results　of　his　laboratory　experiments。　In　short；　chemistry　is　what　alchemy　never　could　be；　an　inductive　science。　　But　this　transition　from　one　point　of　view　to　an　exactly　opposite　one　was　necessarily　a　very　slow　process。　Ideas　that　have　held　undisputed　sway　over　the　minds　of　succeeding　generations　for　hundreds　of　years　cannot　be　overthrown　in　a　moment；　unless　the　agent　of　such　an　overthrow　be　so　obvious　that　it　cannot　be　challenged。　　The　rudimentary　chemistry　that　overthrew　alchemy　had　nothing　so　obvious　and　palpable。

The　great　first　step　was　the　substitution　of　the　one　principle；　phlogiston；　for　the　three　principles；　salt；　sulphur；　and　mercury。　We　have　seen　how　the　experiment　of　burning　or　calcining　such　a　metal　as　lead　〃destroyed〃　the　lead　as　such；　leaving　an　entirely　different　substance　in　its　place；　and　how　the　original　metal　could　be　restored　by　the　addition　of　wheat　to　the　calcined　product。　To　the　alchemist　this　was　〃mortification〃　and　〃revivification〃　of　the　metal。　　For；　as　pointed　out　by　Paracelsus；　〃anything　that　could　be　killed　by　man　could　also　be　revivified　by　him；　although　this　was　not　possible　to　the　things　killed　by　God。〃　　The　burning　of　such　substances　as　wood；　wax；　oil；　etc。；　was　also　looked　upon　as　the　same　〃killing〃　process；　and　the　fact　that　the　alchemist　was　unable　to　revivify　them　was　regarded　as　simply　the　lack　of　skill　on　his　part；　and　in　no　wise　affecting　the　theory　itself。

But　the　iconoclastic　spirit；　if　not　the　acceptance　of　all　the　teachings；　of　the　great　Paracelsus　had　been　gradually　taking　root　among　the　better　class　of　alchemists；　and　about　the　middle　of　the　seventeenth　century　Robert　Boyle　（1626…1691）　called　attention　to　the　possibility　of　making　a　wrong　deduction　from　the　phenomenon　of　the　calcination　of　the　metals；　because　of　a　very　important　factor；　the　action　of　the　air；　which　was　generally　overlooked。　　And　he　urged　his　colleagues　of　the　laboratories　to　give　greater　heed　to　certain　other　phenomena　that　might　pass　unnoticed　in　the　ordinary　calcinating　process。　In　his　work；　The　Sceptical　Chemist；　he　showed　the　reasons　for　doubting　the　threefold　constitution　of　matter；　and　in　his　General　History　of　the　Air　advanced　some　novel　and　carefully　studied　theories　as　to　the　composition　of　the　atmosphere。　This　was　an　important　step；　and　although　Boyle　is　not　directly　responsible　for　the　phlogiston　theory；　it　is　probable　that　his　experiments　on　the　atmosphere　influenced　considerably　the　real　founders；　Becker　and　Stahl。

Boyle　gave　very　definitely　his　idea　of　how　he　thought　air　might　be　composed。　〃I　conjecture　that　the　atmospherical　air　consists　of　three　different　kinds　of　corpuscles；〃　he　says；　〃the　first；　those　numberless　particles　which；　in　the　form　of　vapors　or　dry　exhalations；　ascend　from　the　earth；　water；　minerals；　vegetables；　animals；　etc。；　in　a　word；　whatever　substances　are　elevated　by　the　celestial　or　subterraneal　heat；　and　thence　diffused　into　the　atmosphere。　　The　second　may　be　yet　more　subtle；　and　consist　of　those　exceedingly　minute　atoms；　the　magnetical　effluvia　of　the　earth；　with　other　innumerable　particles　sent　out　from　the　bodies　of　the　celestial　luminaries；　and　causing；　by　their　influence；　the　idea　of　light　in　us。　　The　third　sort　is　its　characteristic　and　essential　property；　I　mean　permanently　elastic　parts。　Various　hypotheses　may　be　framed　relating　to　the　structure　of　these　later　particles　of　the　air。　　They　might　be　resembled　to　the　springs　of　watches；　coiled　up　and　endeavoring　to　restore　themselves；　to　wool；　which；　being　compressed；　has　an　elastic　force；　to　slender　wires　of　different　substances；　consistencies；　lengths；　and　thickness；　in　greater　curls　or　less；　near　to；　or　remote　from　each　other；　etc。；　yet　all　continuing　springy；　expansible；　and　compressible。　Lastly；　they　may　also　be　compared　to　the　thin　shavings　of　different　kinds　of　wood；　various　in　their　lengths；　breadth；　and　thickness。　And　this；　perhaps；　will　seem　the　most　eligible　hypothesis；　because　it；　in　some　measure；　illustrates　the　production　of　the　elastic　particles　we　are　considering。　　For　no　art　or　curious　instruments　are　required　to　make　these　shavings　whose　curls　are　in　no　wise　uniform；　but　seemingly　casual；　and　what　is　more　remarkable；　bodies　that　before　seemed　unelastic；　as　beams　and　blocks；　will　afford　them。〃＇1＇

Although　this　explanation　of　the　composition　of　the　air　is　most　crude；　it　had　the　effect　of　directing　attention　to　the　fact　that　the　atmosphere　is　not　〃mere　nothingness；〃　but　a　〃something〃　with　a　definite　composition；　and　this　served　as　a　good　foundation　for　future　investigations。　　To　be　sure；　Boyle　was　neither　the　first　nor　the　only　chemist　who　had　suspected　that　the　air　was　a　mixture　of　gases；　and　not　a　simple　one；　and　that　only　certain　of　these　gases　take　part　in　the　process　of　calcination。　　Jean　Rey；　a　French　physician；　and　John　Mayow；　an　Englishman；　had　preformed　experiments　which　showed　conclusively　that　the　air　was　not　a　simple　substance；　but　Boyle's　work　was　better　known；　and　in　its　effect　probably　more　important。　But　with　all　Boyle's　explanations　of　the　composition　of　air；　he　still　believed　that　there　was　an　inexplicable　something；　a　〃vital　substance；〃　which　he　was　unable　to　fathom；　and　which　later　became　the　basis　of　Stahl's　phlogiston　theory。　Commenting　on　this　mysterious　substance；　Boyle　says：　〃The；　difficulty　we　find　in　keeping　flame　and　fire　alive；　though　but　for　a　little　time；　without　air；　renders　it　suspicious　that　there　be　dispersed　through　the　rest　of　the　atmosphere　some　odd　substance；　either　of　a　solar；　astral；　or　other　foreign　nature；　on　account　of　which　the　air　is　so　necessary　to　the　substance　of　flame！〃　It　was　this　idea　that　attracted　the　attention　of　George　Ernst　Stahl　（1660…1734）；　a　professor　of　medicine　in　the　University　of　Halle；　who　later　founded　his　new　theory　upon　it。　　Stahl's　theory　was　a　development　of　an　earlier　chemist；　Johann　Joachim　Becker　（1635…1682）；　in　whose　footsteps　he　followed　and　whose　experiments　he　carried　further。

In　many　experiments　Stahl　had　been　struck　with　the　fact　that　certain　substances；　while　differing　widely；　from　one　an