Таємничий острів

           Theywerefinishedbeforethetransformationofthesulphuretintosulphateofironhadbeenaccomplished.Duringthefollowingdaysthesettlershadtimetoconstructafurnaceofbricksofaparticulararrangement,toserveforthedistillationofthesulphateorironwhenithadbeenobtained.Allthiswasfinishedaboutthe18thofMay,nearlyatthetimewhenthechemicaltransformationterminated.GideonSpilett,Herbert,Neb,andPencroft,skillfullydirectedbytheengineer,hadbecomemostcleverworkmen.Beforeallmasters,necessityistheonemostlistenedto,andwhoteachesthebest.

           Whentheheapofpyriteshadbeenentirelyreducedbyfire,theresultoftheoperation,consistingofsulphateofiron,sulphateofalumina,flint,remainsofcoal,andcinderswasplacedinabasinfulofwater.Theystirredthismixture,letitsettle,thendecantedit,andobtainedaclearliquidcontaininginsolutionsulphateofironandsulphateofalumina,theothermattersremainingsolid,sincetheyareinsoluble.Lastly,thisliquidbeingpartlyevaporated,crystalsofsulphateofironweredeposited,andthenotevaporatedliquid,whichcontainedthesulphateofalumina,wasthrownaway.

           CyrusHardinghadnowathisdisposalalargequantityofthesesulphateofironcrystals,fromwhichthesulphuricacidhadtobeextracted.Themakingofsulphuricacidisaveryexpensivemanufacture.Considerableworksarenecessary—aspecialsetoftools,anapparatusofplatina,leadenchambers,unassailablebytheacid,andinwhichthetransformationisperformed,etc.