a history of science-2-第29章

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　some　alchemists　they　were　regarded　as　lepers；　who；　when　cured　of　their　leprosy；　would　become　gold。　And　since　nature　intended　that　all　things　should　be　perfect；　it　was　the　aim　of　the　alchemist　to　assist　her　in　this　purifying　process；　and　incidentally　to　gain　wealth　and　prolong　his　life。　By　other　alchemists　the　process　of　transition　from　baser　metals　into　gold　was　conceived　to　be　like　a　process　of　ripening　fruit。　The　ripened　product　was　gold；　while　the　green　fruit；　in　various　stages　of　maturity；　was　represented　by　the　base　metals。　Silver；　for　example；　was　more　nearly　ripe　than　lead；　but　the　difference　was　only　one　of　〃digestion；〃　and　it　was　thought　that　by　further　〃digestion〃　lead　might　first　become　silver　and　eventually　gold。　In　other　words；　Nature　had　not　completed　her　work；　and　was　wofully　slow　at　it　at　best；　but　man；　with　his　superior　faculties；　was　to　hasten　the　process　in　his　laboratoriesif　he　could　but　hit　upon　the　right　method　of　doing　so。　It　should　not　be　inferred　that　the　alchemist　set　about　his　task　of　assisting　nature　in　a　haphazard　way；　and　without　training　in　the　various　alchemic　laboratory　methods。　On　the　contrary；　he　usually　served　a　long　apprenticeship　in　the　rudiments　of　his　calling。　He　was　obliged　to　learn；　in　a　general　way；　many　of　the　same　things　that　must　be　understood　in　either　chemical　or　alchemical　laboratories。　The　general　knowledge　that　certain　liquids　vaporize　at　lower　temperatures　than　others；　and　that　the　melting…points　of　metals　differ　greatly；　for　example；　was　just　as　necessary　to　alchemy　as　to　chemistry。　The　knowledge　of　the　gross　structure；　or　nature；　of　materials　was　much　the　same　to　the　alchemist　as　to　the　chemist；　and；　for　that　matter；　many　of　the　experiments　in　calcining；　distilling；　etc。；　were　practically　identical。　To　the　alchemist　there　were　three　principlessalt；　sulphur；　and　mercuryand　the　sources　of　these　principles　were　the　four　elementsearth；　water；　fire；　and　air。　These　four　elements　were　accountable　for　every　substance　in　nature。　Some　of　the　experiments　to　prove　this　were　so　illusive；　and　yet　apparently　so　simple；　that　one　is　not　surprised　that　it　took　centuries　to　disprove　them。　That　water　was　composed　of　earth　and　air　seemed　easily　proven　by　the　simple　process　of　boiling　it　in　a　tea…kettle；　for　the　residue　left　was　obviously　an　earthy　substance；　whereas　the　steam　driven　off　was　supposed　to　be　air。　The　fact　that　pure　water　leaves　no　residue　was　not　demonstrated　until　after　alchemy　had　practically　ceased　to　exist。　It　was　possible　also　to　demonstrate　that　water　could　be　turned　into　fire　by　thrusting　a　red…hot　poker　under　a　bellglass　containing　a　dish　of　water。　Not　only　did　the　quantity　of　water　diminish；　but；　if　a　lighted　candle　was　thrust　under　the　glass；　the　contents　ignited　and　burned；　proving；　apparently；　that　water　had　been　converted　into　fire。　These；　and　scores　of　other　similar　experiments；　seemed　so　easily　explained；　and　to　accord　so　well　with　the　〃four　elements〃　theory；　that　they　were　seldom　questioned　until　a　later　age　of　inductive　science。　But　there　was　one　experiment　to　which　the　alchemist　pinned　his　faith　in　showing　that　metals　could　be　〃killed〃　and　〃revived；〃　when　proper　means　were　employed。　It　had　been　known　for　many　centuries　that　if　any　metal；　other　than　gold　or　silver；　were　calcined　in　an　open　crucible；　it　turned；　after　a　time；　into　a　peculiar　kind　of　ash。　This　ash　was　thought　by　the　alchemist　to　represent　the　death　of　the　metal。　But　if　to　this　same　ash　a　few　grains　of　wheat　were　added　and　heat　again　applied　to　the　crucible；　the　metal　was　seen　to　〃rise　from　its　ashes〃　and　resume　its　original　forma　well…known　phenomenon　of　reducing　metals　from　oxides　by　the　use　of　carbon；　in　the　form　of　wheat；　or；　for　that　matter；　any　other　carbonaceous　substance。　Wheat　was；　therefore；　made　the　symbol　of　the　resurrection　of　the　life　eternal。　Oats；　corn；　or　a　piece　of　charcoal　would　have　〃revived〃　the　metals　from　the　ashes　equally　well；　but　the　mediaeval　alchemist　seems　not　to　have　known　this。　However；　in　this　experiment　the　metal　seemed　actually　to　be　destroyed　and　revivified；　and；　as　science　had　not　as　yet　explained　this　striking　phenomenon；　it　is　little　wonder　that　it　deceived　the　alchemist。　Since　the　alchemists　pursued　their　search　of　the　magic　stone　in　such　a　methodical　way；　it　would　seem　that　they　must　have　some　idea　of　the　appearance　of　the　substance　they　sought。　Probably　they　did；　each　according　to　his　own　mental　bias；　but；　if　so；　they　seldom　committed　themselves　to　writing；　confining　their　discourses　largely　to　speculations　as　to　the　properties　of　this　illusive　substance。　Furthermore；　the　desire　for　secrecy　would　prevent　them　from　expressing　so　important　a　piece　of　information。　But　on　the　subject　of　the　properties；　if　not　on　the　appearance　of　the　〃essence；〃　they　were　voluminous　writers。　It　was　supposed　to　be　the　only　perfect　substance　in　existence；　and　to　be　confined　in　various　substances；　in　quantities　proportionate　to　the　state　of　perfection　of　the　substance。　Thus；　gold　being　most　nearly　perfect　would　contain　more；　silver　less；　lead　still　less；　and　so　on。　The　〃essence〃　contained　in　the　more　nearly　perfect　metals　was　thought　to　be　more　potent；　a　very　small　quantity　of　it　being　capable　of　creating　large　quantities　of　gold　and　of　prolonging　life　indefinitely。　It　would　appear　from　many　of　the　writings　of　the　alchemists　that　their　conception　of　nature　and　the　supernatural　was　so　confused　and　entangled　in　an　inexplicable　philosophy　that　they　themselves　did　not　really　understand　the　meaning　of　what　they　were　attempting　to　convey。　But　it　should　not　be　forgotten　that　alchemy　was　kept　as　much　as　possible　from　the　ignorant　general　public；　and　the　alchemists　themselves　had　knowledge　of　secret　words　and　expressions　which　conveyed　a　definite　meaning　to　one　of　their　number；　but　which　would　appear　a　meaningless　jumble　to　an　outsider。　Some　of　these　writers　declared　openly　that　their　writings　were　intended　to　convey　an　entirely　erroneous　impression；　and　were　sent　out　only　for　that　purpose。　However；　while　it　may　have　been　true　that　the　vagaries　of　their　writings　were　made　purposely；　the　case　is　probably　more　correctly　explained　by　saying　that　the　very　nature　of　the　art　made　definite　statements　impossible。　They　were　dealing　with　something　that　did　not　existcould　not　exist。　Their　attempted　descriptions　became；　therefore；　the　language　of　romance　rather　than　the　language　of　science。　But　if　the　alchemists　themselves　were　usually　silent　as　to　the　appearance　of　the　actual　substance　of　the　philosopher's　stone；　there　were　numberless　other　writers　who　were　less　reticent。　By　some　it　was　supposed　to　be　a　stone；　by　others　a　liquid　or　elixir；　but　more　commonly　it　was　described　as　a　black　powder。　It　also　possessed　different　degrees　of　efficiency　according　to　its　degrees　of　purity；　certain　forms　only　possessing　the　power　of　turning　base　metals　into　gold；　while　others　gave　eternal　youth　and　life　or　different　degrees　of　health。　Thus　an　alchemist；　who　had　made　a　partial　discovery　of　this　substance；　could　prolong　life　a　certain　number　of　years　only；　or；　possessing　only　a　small　and　inadequate　amount　of　the　magic　powder；　he　was　obliged　to　give　up　the　ghost　when　the　effect　of　this　small　quantity　had　passed　away。　This　be