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fsilverfromcheap ermaterials، especiallycopper، orwith bringingaboutext ernalandsuperfic ialchangesincolo urinthecheaperan dbasermetal. the contentsofthetre atiseremindoneof thoseoftheegypti anpapyrusmanuscr iptsonthesame subjectdescribed byberthelotinhis archeologieethis toiredessciences (pp. ٢٦٦ - ٣٠٧) withthis differencethat، whereasthelatter wereintendedfort heguidanceofarti sans، thearabicworks areessentiallypr acticaltreatises onnaturalphiloso phy، writteninthecaus eoftheadvancemen t ofscience، andnotthereforep rimarilyforthepu rposeofamassingw ealthbyfaudulent means. fromtheelaborate detailsgiveninth einas- sanahitseemsfair lyobviousthatthe authorhad actuallypersonal lytestedthevario usprocesseshedes cribes ... " ... the'ainas- san'، asitsnameimplies، containstheessen tialofthechemica lknowledgeofthe llthcentury، withsomepractica lhintsforaidingt heworkers. theseventhchapte rofthebook inparticularcont ainseasyprocesse sineveryusefulbr anchoftheartasit prevailedatthatt ime. thescopeofchemic alscienceinthemi ddleeastwasthena lmostentirelycon finedtoastudyof thecommonmetalsa ndguidedmainlyby thepossibilityof effectingthetran smutationofbaser metalsintogoldan dsilver- theavowedobjecto fthealchemicalar t. itisthereforenot atallsur- prisingthattheme thodsdescribedin thechpterunderco nsiderationareap parentlyconcerne d withproducingpas sableimitationso