meteorology-第21部分

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names　appropriated　to　them。　Liquids　too；　like　milk　and　must；　are



said　to　undergo　a　process　of　'boiling'　when　the　external　fire　that



surrounds　and　heats　them　changes　the　savour　in　the　liquid　into　a　given



form；　the　process　being　thus　in　a　way　like　what　we　have　called



boiling。



　　The　end　of　the　things　that　undergo　boiling；　or　indeed　any　form　of



concoction；　is　not　always　the　same：　some　are　meant　to　be　eaten；　some



drunk；　and　some　are　intended　for　other　uses；　for　instance　dyes；　too；



are　said　to　be　'boiled'。



　　All　those　things　then　admit　of　'boiling'　which　can　grow　denser；



smaller；　or　heavier；　also　those　which　do　that　with　a　part　of



themselves　and　with　a　part　do　the　opposite；　dividing　in　such　a　way



that　one　portion　thickens　while　the　other　grows　thinner；　like　milk



when　it　divides　into　whey　and　curd。　Oil　by　itself　is　affected　in



none　of　these　ways；　and　therefore　cannot　be　said　to　admit　of



'boiling'。　Such　then　is　the　pfcies　of　concoction　known　as　'boiling'；



and　the　process　is　the　same　in　an　artificial　and　in　a　natural



instrument；　for　the　cause　will　be　the　same　in　every　case。



　　Imperfect　boiling　is　the　form　of　inconcoction　opposed　to　boiling。



Now　the　opposite　of　boiling　properly　so　called　is　an　inconcoction　of



the　undetermined　matter　in　a　body　due　to　lack　of　heat　in　the



surrounding　liquid。　（Lack　of　heat　implies；　as　we　have　pointed　out；　the



presence　of　cold。）　The　motion　which　causes　imperfect　boiling　is



different　from　that　which　causes　boiling；　for　the　heat　which



operates　the　concoction　is　driven　out。　The　lack　of　heat　is　due



either　to　the　amount　of　cold　in　the　liquid　or　to　the　quantity　of



moisture　in　the　object　undergoing　the　process　of　boiling。　Where　either



of　these　conditions　is　realized　the　heat　in　the　surrounding　liquid



is　too　great　to　have　no　effect　at　all；　but　too　small　to　carry　out



the　process　of　concocting　uniformly　and　thoroughly。　Hence　things　are



harder　when　they　are　imperfectly　boiled　than　when　they　are　boiled；　and



the　moisture　in　them　more　distinct　from　the　solid　parts。　So　much　for



the　definition　and　causes　of　boiling　and　imperfect　boiling。



　　Broiling　is　concoction　by　dry　foreign　heat。　Hence　if　a　man　were　to



boil　a　thing　but　the　change　and　concoction　in　it　were　due；　not　to



the　heat　of　the　liquid　but　to　that　of　the　fire；　the　thing　will　have



been　broiled　and　not　boiled　when　the　process　has　been　carried　to



completion：　if　the　process　has　gone　too　far　we　use　the　word　'scorched'



to　describe　it。　If　the　process　leaves　the　thing　drier　at　the　end　the



agent　has　been　dry　heat。　Hence　the　outside　is　drier　than　the　inside；



the　opposite　being　true　of　things　boiled。　Where　the　process　is



artificial；　broiling　is　more　difficult　than　boiling；　for　it　is



difficult　to　heat　the　inside　and　the　outside　uniformly；　since　the



parts　nearer　to　the　fire　are　the　first　to　get　dry　and　consequently　get



more　intensely　dry。　In　this　way　the　outer　pores　contract　and　the



moisture　in　the　thing　cannot　be　secreted　but　is　shut　in　by　the　closing



of　the　pores。　Now　broiling　and　boiling　are　artificial　processes；　but



the　same　general　kind　of　thing；　as　we　said；　is　found　in　nature　too。



The　affections　produced　are　similar　though　they　lack　a　name；　for　art



imitates　nature。　For　instance；　the　concoction　of　food　in　the　body　is



like　boiling；　for　it　takes　place　in　a　hot　and　moist　medium　and　the



agent　is　the　heat　of　the　body。　So；　too；　certain　forms　of　indigestion



are　like　imperfect　boiling。　And　it　is　not　true　that　animals　are



generated　in　the　concoction　of　food；　as　some　say。　Really　they　are



generated　in　the　excretion　which　putrefies　in　the　lower　belly；　and



they　ascend　afterwards。　For　concoction　goes　on　in　the　upper　belly



but　the　excretion　putrefies　in　the　lower：　the　reason　for　this　has　been



explained　elsewhere。



　　We　have　seen　that　the　opposite　of　boiling　is　imperfect　boiling：



now　there　is　something　correspondingly　opposed　to　the　species　of



concoction　called　broiling；　but　it　is　more　difficult　to　find　a　name



for　it。　It　would　be　the　kind　of　thing　that　would　happen　if　there



were　imperfect　broiling　instead　of　broiling　proper　through　lack　of



heat　due　to　deficiency　in　the　external　fire　or　to　the　quantity　of



water　in　the　thing　undergoing　the　process。　For　then　we　should　get



too　much　heat　for　no　effect　to　be　produced；　but　too　little　for



concoction　to　take　place。



　　We　have　now　explained　concoction　and　inconcoction；　ripening　and



rawness；　boiling　and　broiling；　and　their　opposites。







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　　We　must　now　describe　the　forms　taken　by　the　passive　qualities　the



moist　and　the　dry。　The　elements　of　bodies；　that　is；　the　passive



ones；　are　the　moist　and　the　dry；　the　bodies　themselves　are



compounded　of　them　and　whichever　predominates　determines　the　nature　of



the　body；　thus　some　bodies　partake　more　of　the　dry；　others　of　the



moist。　All　the　forms　to　be　described　will　exist　either　actually；　or



potentially　and　in　their　opposite：　for　instance；　there　is　actual



melting　and　on　the　other　hand　that　which　admits　of　being　melted。



　　Since　the　moist　is　easily　determined　and　the　dry　determined　with



difficulty；　their　relation　to　one　another　is　like　that　of　a　dish　and



its　condiments。　The　moist　is　what　makes　the　dry　determinable；　and　each



serves　as　a　sort　of　glue　to　the　other…as　Empedocles　said　in　his　poem



on　Nature；　'glueing　meal　together　by　means　of　water。'　Thus　the



determined　body　involves　them　both。　Of　the　elements　earth　is



especially　representative　of　the　dry；　water　of　the　moist；　and



therefore　all　determinate　bodies　in　our　world　involve　earth　and　water。



Every　body　shows　the　quality　of　that　element　which　predominates　in　it。



It　is　because　earth　and　water　are　the　material　elements　of　all



bodies　that　animals　live　in　them　alone　and　not　in　air　or　fire。



　　Of　the　qualities　of　bodies　hardness　and　softness　are　those　which



must　primarily　belong　to　a　determined　thing；　for　anything　made　up　of



the　dry　and　the　moist　is　necessarily　either　hard　or　soft。　Hard　is　that



the　surface　of　which　does　not　yield　into　itself；　soft　that　which



does　yield　but　not　by　interchange　of　place：　water；　for　instance；　is



not　soft；　for　its　surface　does　not　yield　to　pressure　or　sink　in　but



there　is　an　interchange　of　place。　Those　things　are　absolutely　hard　and



soft　which　satisfy　the　definition　absolutely；　and　those　things



relatively　so　which　do　so　compared　with　another　thing。　Now



relatively　to　one　another　hard　and　soft　are　indefinable；　because　it　is



a　matter　of　degree；　but　since　all　the　objects　of　sense　are



determined　by　reference　to　the　faculty　of　sense　it　is　clearly　the



relation　to　touch　which　determines　that　which　is　hard　and　soft



absolutely；　and　touch　is　that　which　we　use　as　a　standard　or　mean。　So



we　call　that　which　exceeds　it　hard　and　that　which　falls　short　of　it



soft。







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　　A　body　determined　by　its　own　boundary　must　be　either　hard　or　soft；



for　it　either　yields　or　does　not。



　　It　must　also　be　concrete：　or　it　could　not　be　so　determined。　So　since



everything　that　is　determined　and　solid　is　either　hard　or　soft　and



these　qualities　are　due　to　concretion；　all　composite　and　determined



bodies　must　involve　concretion。　Concretion　therefore　must　be



discussed。



　　Now　there　are　two　causes　besides　matter；　the　agent　and　the　quality



brought　about；　the　agent　being　the　efficient　cause；　the　quality　the



formal　cause。　Hence　concretion　and　disaggregation；　drying　and



moistening；　must　have　these　two　causes。



　　But　since　concretion　is　a　form　of　drying　let　us　speak　of　the



latter　first。



　　As　we　have　explained；　the　agent　operates　by　means　of　two　qualities



and　the　patient　is　acted　on　in　virtue　of　two　qualities：　action　takes



place　by　means　of　heat　or　cold；　and　the　quality　is　produced　either



by　the　presence　or　by　the　absence　of　heat　or　cold；　but　that　which　is



acted　upon　is　moist　or　dry　or　a　compound　of　both。　Water　is　the　element



characterized　by　the　moist；　earth　that　characterized　by　the　dry；　for



these　among　the　elements　that　admit　the　qualities　moist　and　dry　are



passive。　Therefore　cold；　too；　being　found　in　water　and　earth　（both



of　which　we　recognize　to　be　cold）；　must　be　reckoned　rather　as　a



passive　quality。　It　is　active　only　as　contributing　to　destruction　or



incidentally　in　the　manner　described　before；　for　cold　is　sometimes



actually　said　to　burn　and　to　warm；　but　not　in　the　same　way　as　heat



does；　but　by　collecting　and　concentrating　heat。



　　The　subjects　of　drying　are　water　and　the　various　watery　fluids　and



those　bodies　which　contain　water　either　foreign　or　connatural。　By



foreign　I　mean　like　the　water　in　wool；　by　connatural；　like　that　in



milk。　The　watery　fluids　are　wine；　urine；　whey；　and　in　general　those



fluids　which　have　no　sediment　or　only　a　little；　except　where　this



absence　of　sediment　is　due　to　viscosity。　For　in　some　cases；　in　oil　and



pitch　for　instance；　it　is　the　viscosity　which　prevents　any　sediment



from　appearing。



　　It　is　always　a　process　of　heating　or　cooling　that　dries　things；



but　the　agent　in　both　cases　is　heat；　either　internal　or　external。



For　even　when　things　are　dried　by　cooling；　like　a　garment；　where　the



moisture　exists　separately　it　is　the　internal　heat　that　dries　them。　It



carries　off　the　moisture　in　the　shape　of　vapour　（if　there　is　not　too



much　of　it）；　being　itself　driven　out　by　the　surrounding　cold。　So



everything　is　dried；　as　we　have　said；　by　a　process　either　of　heating



or　cooling；　but　the　agent　is　always　heat；　either　internal　or　external；



carrying　off　the　moisture　in　vapour。　By　external　heat　I　mean　as



where　things　are　boiled：　by　internal　where　the　heat　breathes　out　and



takes　away　and　uses　up　its　moisture。　So　much　for　drying。







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