资源描述：
《oil by gc thornley》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。
1、OilByG.C.ThornleyTherearethreemaingroupsofoils:animal,vegetable,andmineral.Greatquantitiesofanimaloilcomefromwhales,thoseenormouscreaturesoftheseawhicharethelargestremaininganimalsintheworld.ToprotectthewhalefromthecoldoftheArcticseas,naturehasprovideditwithathickc
2、overingoffatcalledblubber.Whenthewhaleiskilled,theblubberisstrippedoffandboileddown,eitheronboardshiporonshore.Itproducesagreatquantityofoilwhichcanbemadeintofoodforhumanconsumption.Afewothercreaturesyieldoil,butnonesomuchasthewhale. Theliversofthecodandthehalibut
3、,twokindsoffish,yieldnourishingoil. Bothcodliveroilandhalibutliveroilaregiventosickchildrenandotherinvalidswhoneedcertainvitamins.Theseoilsmaybeboughtatanychemist’s.Vegetableoilhasbeenknownfromantiquity.Nohouseholdcangetonwithoutit,foritisusedincooking.Perfumesmay
4、bemadefromtheoilsofcertainflowers.Soapsaremadefromvegetableandanimaloils.Totheordinaryman,onekindofoilmaybeasimportantasanother.Butwhenthepoliticianortheengineerreferstooil,healmostalwaysmeansmineraloil,theoilthatdrivestanks,aeroplanesandwarship,motor-carsanddiesel
5、locomotives;thethatisusedtolubricateallkindsofmachinery.Thisistheoilthathaschangedthelifeofthecommonman.Whenitisrefinedintopetrol,itisusedtodrivetheinternalcombustionengine.Toitweowetheexistenceofthemotor-car,whichhasreplacedtheprivatecarriagedrawnbythehorse.Toitwe
6、owethepossibilityofflying.Ithaschangedthemethodsofwarfareonlandandsea.Thiskindofoilcomesoutoftheearth.Becauseitburnswell,itisusedasfuelandinsomewaysitissuperiortocoalinthisrespect.Manybigshipnowburnoilinsteadofcoal.Becauseitburnsbrightly,itisusedforilluminationcoun
7、tlesshomesarestillilluminatedwithoil-burninglamps.Becauseitisveryslippery,itisusedforlubrication.Twometalsurfacesrubbingtogethercausefrictionandheat;butiftheyareseparatedbyathinfilmofoil,thefrictionandheatarereduced.Nomachinewouldworkforlongifitwerenotproperlylubri
8、cated.Theoilusedforthispurposemustbeofthecorrectthickness;ifitistoothinitwillnotgivesufficientlubrication,andifitistoothickitwillnotreachallparts
