WeareinformedthatitwaswhileRichardReynoldshadchargeoftheCoalbrookdaleworksthatafurtherimportantimprovementwaseffectedinthemanufactureofironbypit-coal。Uptothistimetheconversionofcrudeorcastironintomalleableorbarironhadbeeneffectedentirelybymeansofcharcoal。Theprocesswascarriedoninafirecalledafinery，somewhatlikethatofasmith’sforge；theironbeingexposedtotheblastofpowerfulbellows，andinconstantcontactwiththefuel。Inthefirstprocessoffusingtheironstone，coalhadbeenusedforsometimewithincreasingsuccess；butthequestionarose，whethercoalmightnotalsobeusedwitheffectinthesecondorrefiningstage。Twooftheforemen，namedCranege，suggestedtoMr。Reynoldsthatthismightbeperformedinwhatiscalledareverberatoryfurnace，*
[footnote……
Reverberatory，socalledbecausetheflameorcurrentofheatedgasesfromthefueliscausedtobereverberatedorreflecteddownuponthesubstanceunderoperationbeforepassingintothechimney。ItiscuriousthatRovenson，inhisTreatiseofMetallicaof1613，describesareverberatoryfurnaceinwhichironwastobesmeltedbypit-coal，thoughitdoesnotappearthathesucceededinperfectinghisinvention。Dr。Percy，inhisexcellentworkonMetallurgy，thusdescribesareverberatoryfurnace：——”Itconsistsessentiallyofthreeparts——afireplaceatoneend，astackorchimneyattheother，andabedbetweenbothonwhichthematterisheated。Thefireplaceisseparatedfromthebedbyalowpartitionwallcalledthefire-bridge，andbotharecoveredbyanarchedroofwhichrisesfromtheendwallofthefireplaceandgraduallydipstowardthefurthestendofthebedconnectedwiththestack。Ononeorbothsidesofthebed，orattheendnearthestack，maybeopeningsthroughwhichtheorespreadoverthesurfaceofthebedmaybestirredaboutandexposedtotheactionoftheair。Thematterisheatedinsuchafurnacebyflame，andiskeptfromcontactwiththesolidfuel。TheflameinitscoursefromthefireplacetothestackisreflecteddownwardsorREVERBERATEDonthematterbeneath，whencethenameREVERBERATORYfurnace。”
inwhichtheironshouldnotmixwiththecoal，butbeheatedsolelybytheflame。Mr。Reynoldsgreatlydoubtedthefeasibilityoftheoperation，butheauthorizedtheCranege，tomakeanexperimentoftheirprocess，theresultofwhichwillbefounddescribedinthefollowingextractofaletterfromMr。ReynoldstoMr。ThomasGoldneyofBristol，dated”Coalbrookdale，25thApril，1766”：……”IcomenowtowhatIthinkamatterofverygreatconsequence。
ItissometimesinceThos。Cranege，whoworksatBridgenorthForge，andhisbrotherGeorge，oftheDale，spoketomeaboutanotiontheyhadconceivedofmakingbarironwithoutwoodcharcoal。Itoldthem，consistentwiththenotionIhadadoptedincommonwithallothersI