,transcrib]'s ,note3 ,m9or inconsi/5cies 9 spell+1 punctuation & =matt+ are reta9$ z 9 ! orig9al4 ,:]e detail$ corrections h be5 made on ! text ^! are li/$ at ! end ( ?is docum5t4 ,disclaim]3 ,?is is a "w ( hi/orical int]e/ only & mu* ( ! sci5tific cont5t has be5 sup]s$$4 ,!re are num]\s exp]im5ts describ$ 9 ?is book :i* are haz>d\s & %\ld n be attempt$4 ,advice giv5 on h&l+ toxic sub/ances1 electrical app>atus etc4 %\ld n be foll[$4 ,d n try ?is at home6 99 99 99 99 99 ,,common ,,sci5ce ,,new-,,_w ,,sci5ce ,,s]ies ,edit$ by ,john ,w4 ,rit*ie 99 99 99 99 99 ,,sci5ce ,,= ,,beg9n]s ,by ,delos ,fall ,,trees1 ,,/>s1 ,,& ,,birds ,by ,edw9 ,l9coln ,moseley ,,common ,,sci5ce ,by ,c>leton ,w4 ,wa%burne ,,human ,,physiology ,by ,john ,w4 ,rit*ie ,,sanitation ,,& ,,physiology ,by ,john ,w4 ,rit*ie ,,laboratory ,,manual ,,= ,,use ,,) ,,human ,,physiology ,by ,c>l ,h>tman 99 99 99 99 99 ,,ex]cise ,,& ,,review ,,book ,,9 ,,biology ,by ,j4 ,g4 ,blaisdell ,,p]sonal ,,hygi5e ,,& ,,home ,,nurs+ ,by ,l\isa ,c4 ,lippitt ,,sci5ce ,,( ,,plant ,,life ,by ,edg> ,nelson ,transeau 99 99 99 99 99 ,,zo,,logy ,by ,t4 ,d4 ,a4 ,cock]ell ,,exp]im5tal ,,organic ,,*emi/ry ,by ,augu/us ,p4 ,we/ 99 99 99 99 99 ,,new-,,_w ,,sci5ce ,,s]ies ,edit$ by ,john ,w4 ,rit*ie ,,common ,,sci5ce by ,c>leton ,w4 ,wa%burne ,sup]9t5d5t ( ,s*ools1 ,w9netka1 ,ill9ois ,=m]ly ,sup]visor 9 ,physical ,sci5ces & ,in/ructor 9 ,educational ,psy*ology ,/ate ,normal ,s*ool ,san ,francisco1 ,cali=nia ,,illu/rat$ ,,) ,,photographs ,,& ,,draw+s ,yonk]s-on-,hudson1 ,new ,york ,,_w ,,book ,,company #aiba ,,_w ,,book ,,company ,,! ,,h\se ,,( ,,appli$ ,,k ,e/abli%$1 #aije1 by ,casp> ,w4 ,hodgson ,,yonk]s-,,on-,,hudson1 ,,new ,,york #babf ,,prairie ,,av5ue1 ,,*icago ,"o ( ! results ( ! ,_w ,w> has be5 a widespread desire to see ! =ces ( sci5ce :i* prov$ s mighty 9 de/ruction employ$ g5]ally & sy/ematically = ! promotion ( human welf>e4 ,_w ,book ,company1 ^: motto is ,! ,application ( ! ,_w's ,k to ! ,_w's ,ne$s1 has be5 mu* 9 sympa?y ) ! movem5t to make sci5ce an integral "p ( our elem5t>y education1 s t all our p f ! highe/ to ! l[e/ w be able to use x = !mselves & to appreciate ! possibilities ( ameliorat+ ! conditions ( human life by its application to ! problems t confront u4 ,we c\nt x our good =tune1 !re=e1 t we are able at ?is "t to (f] ,common ,sci5ce to ! s*ools4 ,x is "o ( ! new type ( texts t are built on educational rese>* & n by guess1 & we believe x to be a sub/antial contribution to ! tea*+ ( ! subject ,,nwss3,,wcs-#b ,copyright1 #aibj1 by ,_w ,book ,company ,copyright 9 ,great ,brita9 ,all rights res]v$ ,,preface ,a collection ( ab\t #bjjj que/ions ask$ by *ildr5 =ms ! f\ndation on :i* ?is book is built4 ,r ?an decide :at x is t *ildr5 ought to "k1 or :at k c\ld be/ be fitt$ into "s educational !ory1 an attempt 0 made to f9d out :at *ildr5 want to "k4 ,! obvi\s way to discov] ?is 0 to let !m ask que/ions4 ,! que/ions collect$ 7 ask$ by sev]al hundr$ *ildr5 9 ! upp] elem5t>y grades1 ov] a p]iod ( a ye> & a half4 ,!y 7 !n sort$ & classifi$ accord+ to ! sci5tific pr9ciples ne$$ 9 ord] to answ] !m4 ,^! pr9ciples con/itute ! skeleton ( ?is c\rse4 ,! que/ions gave a v fair indication ( ! p>ts ( sci5ce 9 :i* *ildr5 are mo/ int]e/$4 ,physics1 9 simple1 qualitative =m1--n ma!matical physics1 ( c\rse1--comes fir/2 a/ronomy next2 *emi/ry1 geology1 & c]ta9 =ms ( physical geography 7wea!r1 volcanoes1 e>?quakes1 etc47 come ?ird2 biology1 ) physiology & hygi5e1 is a close f\r?2 & nature /udy1 9 ! ord9>y s*ool s5se ( ! t]m1 comes 9 h>dly at all4 ,! *apt] head+s ( ?is book might indicate t ! c\rse has to d ) physics & *emi/ry only4 ,?is is because g5]al physical & *emical pr9ciples =m a unify+ & inclusive matrix = ! mass ( applications4 ,b ! examples & descriptions ?r\gh\t ! book include physical geography & ! life sci5ces4 ,descriptive a/ronomy & geology h1 h[ev]1 be5 omitt$4 ,^! two subjects c be be/ grasp$ 9 a read+ c\rse & field trips1 & !y h be5 incorporat$ 9 sep>ate books4 ,! be/ me?od ( pres5t+ ! pr9ciples to ! *ildr5 0 ! next problem4 ,! /udy ( ! que/ions ask$ _h %[n t ! *ildr5's int]e/s 7 c5t]$ 9 ! explanation ( a wide v>iety ( famili> facts 9 ! _w ab\t !m4 ,x seem$ evid5t1 !re=e1 t a pres5tation ( ! pr9ciples t w\ld answ] ! que/ions ask$ w\ld be mo/ int]e/+ to ! *ild4 ,exp]i5ce ) _m diff]5t classes _h %[n t x is n necess>y to subord9ate ^! explanations ( :at *ildr5 really wi% to "k to o!r me?ods ( in/ruction ( d\btful int]e/ value4 ,obvi\sly ! quantitative me?ods ( ! high s*ool & college 7 unsuitable = pupils ( ?is age4 ,we want *ildr5 to be attract$ to sci5ce1 n repell$ by x4 ,! assumption t sci5tific me?od c be taught to *ildr5 by mak+ !m p]=m un9t]e/+1 quantitative exp]im5ts 9 an ef=t to get a result t w tally ) t giv5 9 ! textbook is s palpably unf\nd$ t x is sc>cely necess>y to prove its failure by po9t+ to ! v unsci5tific product ( mo/ ( our high s*ool sci5ce laboratories4 ,aft] a good deal ( exp]im5t+ ) *ildr5 9 a numb] ( sci5ce classes1 ! me?od foll[$ 9 ?is book 0 develop$4 ,briefly1 x is z foll[s3 ,at ! head ( ea* section are sev]al ( ! que/ions :i*1 9 "p1 prompt$ ! writ+ ( ! section4 ,! purpose ( ^! is to let ! *ildr5 "k def9itely :at _! goal is :5 !y beg9 a section4 ,! fact t ! que/ions _h _! orig9 9 ! m9ds ( *ildr5 gives reasonable assurance t !y w to "s ext5t appeal to *ildr54 ,^! que/ions 9 effect /ate ! problems :i* ! section helps to solve4 ,foll[+ ! que/ions are "s introductory p>agraphs = ar\s+ int]e/ 9 ! problem at h&1--= motivat+ ! *ild fur!r4 ,^! p>agraphs are frequ5tly a n>rative description conta9+ a good _m dramatic elem5ts1 & are writt5 9 conv]sational /yle4 ,! purpose is to awak5 ! *ild's imag9ation & to make cle> ! intimate "p :i* ! pr9ciple "u consid]ation plays 9 8 own life4 ,:5 a pr9ciple is univ]sal1 l gravity1 x is be/ br\ght out by imag9+ :at w\ld happ5 if x ceas$ to exi/4 ,if a pr9ciple is p>ticul> to c]ta9 sub/ances1 l ela/icity1 x sometimes c be br\ght out vividly by imag9+ :at w\ld happ5 if x 7 univ]sal4 ,contra/ is ess5tial to consci\sness4 ,to contra/ a condition t is v common ) an imag9$ condition t is diff]5t br+s ! =m] into vivid consci\sness4 ,incid5tally1 x ar\ses real int]e/4 ,! /ory-l introduction to _m sections is n a sug> coat+ to make ! *ild swall[ a bitt] pill4 ,x is a psy*ologically s\nd me?od ( br++ out ! ess5tial & dramatic features ( a pr9ciple :i* is 9 itself int]e/+1 once ! *ild has grasp$ x4 ,ano!r means = motivat+ ! "w 9 c]ta9 cases consi/s 9 fir/ do+ a dramatic exp]im5t t w ar\se ! pupil's int]e/ & curiosity4 ,/ill ano!r consi/s 9 m]ely call+ ! *ild's att5tion to ! practical value ( ! pr9ciple4 ,foll[+ ^! v>i\s means = gett+ ! pupil's int]e/1 !re are usually "s exp]im5ts design$ to help him solve 8 problem4 ,! exp]im5ts are made z simple & int]e/+ z possible4 ,!y usually require v inexp5sive app>atus & are *os5 or inv5t$ bo? = _! int]e/ value & _! cont5t value4 ,) an explanation ( ! exp]im5ts & ! que/ions t arise1 a pr9ciple is made cle>4 ,!n ! pupil is giv5 an opportunity to apply ! pr9ciple 9 mak+ intelligible "s common fact1 if ! pr9ciple has only intellig5ce value2 or he is ask$ to apply ! pr9ciple to ! solution ( a practical problem :]e ! pr9ciple also has utility value4 ,! inf]5ce ex]cises :i* foll[ ea* section aft] ! fir/ two consi/ ( /atem5ts ( well-kn[n facts expla9able 9 t]ms ( "s ( ! pr9ciples :i* prec$e !m4 ,!y involve a con/ant review ( ! "w :i* has gone be=e1 a review :i* nev]!less is new "w--!y review ! pr9ciples by giv+ !m new applications4 ,fur!rmore1 !y give ! pupil v def9ite tra9+ 9 expla9+ ! common ?+s ar\nd him4 ,= f\r ye>s a mimeograph$ edition ( ?is book has be5 us$ 9 ! elem5t>y dep>tm5t ( ! ,san ,francisco ,/ate ,normal ,s*ool4 ,dur+ t "t v>i\s normal /ud5ts h tri$ x 9 public s*ool classes 9 & ar\nd ,san ,francisco & ,oakl&1 & x has rec5tly be5 us$ 9 ,w9netka1 ,ill9ois4 ,x has be5 twice revis$ ?r\gh\t 9 response to ne$s %[n by ?is use4 ,! book has prov$ itself adaptable to ei!r an individual sy/em ( in/ruction or ! usual class me?ods4 ,,to ,,! ,,tea*] ,d n te/ ! *ildr5 on ! n>rative description :i* introduces mo/ sections1 nor require !m to recite on x4 ,x is !re m]ely to ar\se _! int]e/1 & t is likely to be *eck$ if !y ?9k x is a lesson to be le>n$4 ,x is n at all necess>y = !m to "k ev]y?+ 9 ! introductory p>ts ( ea* section4 ,if ! *ildr5 are int]e/$1 !y w rememb] :at is valuable to !m2 if !y are n1 d n prolong ! agony4 ,! que/ions :i* accompany & foll[ ! exp]im5ts1 ! applications or requir$ explanations at ! ends ( ! sections1 & ! ext5sive inf]5ce ex]cises1 =m an ample te/ ( ! *ild's grasp ( ! pr9ciples "u discussion4 ,x is n necess>y to h ! *ildr5 write up _! exp]im5ts4 ,! exp]im5ts are a means to an end4 ,! end is ! application ( ! pr9ciples to ev]yday facts4 ,if ! *ildr5 c make ^! applications1 x does n matt] h[ mu* ( ! actual exp]im5ts !y rememb]4 ,if possible1 ! exp]im5ts %\ld be done by ! pupils individually or 9 c\ples1 9 a s*ool laboratory4 ,:]e ?is _c be done1 almo/ all ! exp]im5ts c be demon/rat$ f ! tea*]'s desk if electricity1 wat]1 & gas are to be _h4 ,alcohol lamps c be sub/itut$ = gas1 b !y are less satisfactory4 ,x is a good plan to h pupils report additional exemplifications ( ea* pr9ciple f _! home or play life1 & 9 a quick oral review to let ! re/ ( ! class "n ! pr9ciples back ( ea* example4 ,?is c\rse is s arrang$ t x c be us$ accord+ to ! regul> class sy/em ( in/ruction1 or accord+ to ! individual sy/em :]e ea* *ild does 8 own "w at 8 natural rate ( progress4 ,! *ildr5 c c>ry on ! "w ) almo/ no assi/ance f ! tea*]1 if provision is made = _! do+ ! exp]im5ts !mselves & = _! writ+ ! answ]s to ! inf]5ce ex]cises4 ,:5 ! individual sy/em is us$1 ! *ildr5 may write ! inf]5ce ex]cises1 or !y may use !m z a basis = /udy & recite only a few to ! tea*] by way ( te/4 ,9 ! elem5t>y dep>tm5t ( ! ,san ,francisco ,/ate ,normal ,s*ool1 :]e ! individual sy/em is us$1 ! latt] me?od is 9 op]ation4 ,! tea*] has a c>d = ea* pupil1 ea* c>d conta9+ a mimeograph$ li/ ( ! pr9ciples1 ) a blank aft] ea*4 ,:5ev] a pupil correctly expla9s an example1 a figure #a is plac$ 9 ! blank foll[+ t pr9ciple2 :5 he misapplies a pr9ciple1 or fails to apply x1 an x is plac$ aft] x4 ,:5 !re are f\r successive #a's aft] any pr9ciple1 ! tea*] no long] includes t pr9ciple 9 te/+ t *ild4 ,9 ?is way ! numb] ( inf]5ce ex]cises on :i* %e he>s any "o individual recite is greatly r$uc$4 ,?is plan w\ld probably h to be alt]$ 9 ord] to adapt x to p>ticul> conditions4 ,! ,socratic me?od c be employ$ to great advantage 9 h&l+ difficult inf]5ces4 ,! *ildr5 discuss 9 class ! pr9ciple "u :i* an inf]5ce comes1 & ! tea*] guides ! discussion1 :5 necess>y1 by skillfully plac$ que/ions design$ to br+ ! ess5tial problems into relief4#a ,footnote #a3 ,at ! ,cali=nia ,/ate ,normal ,s*ool 9 ,san ,francisco1 ?is c\rse 9 g5]al sci5ce is usually prec$$ by "o 9 introductory sci5ce4 ,! *apt]s & sections 9 ?is book are n ( ev5 l5g?4 ,9 ord] to pres]ve ! unity ( subject matt]1 x 0 felt desirable to divide ! book accord+ to subjects r ?an accord+ to daily lessons4 ,! v>y+ l5g?s ( recitation p]iods 9 diff]5t s*ools1 & ! adaptation ( ! c\rse to individual in/ruction z well z to class "w1 also made a division into lessons impracticable4 ,ea* tea*] w soon discov] ab\t h[ mu* matt] h] class1 if %e uses ! class me?od1 c take ea* day4 ,probably ! av]age section w require ab\t #b days to cov]2 ! longe/ sections1 #e days4 ,! entire c\rse %\ld easily be cov]$ 9 "o ye> ) recitations ( ab\t #be m9utes daily4 ,two #ej-m9ute p]iods a week give a bett] division ( "t & also ought to f9i% ! c\rse 9 a ye>4 ,"u ! individual sy/em1 ! sl[e/ dilig5t *ildr5 f9i% 9 #g or #h s*ool mon?s1 work+ #d half-h\rs weekly4 ,! fa/e/ d x 9 ab\t "o ?ird t "t4 ,^u receipt ( #bj c5ts1 ! publi%]s w s5d a manual prep>$ by ! au?or1 conta9+ full in/ructions z to ! organization & equipm5t ( ! laboratory or demon/ration desk1 complete li/s ( app>atus & mat]ial ne$$1 & directions = ! con/ruction ( a *emical laboratory4 ,! latt] is a laboratory c\rse 9 :i* ! *ildr5 are turn$ loose among all sorts ( int]e/+ mat]ials & app>atus1--kaleidoscope1 microscope1 electric bell1 toy motor1 *emicals t eff]vesce or *ange color :5 put toge!r1 s(t glass tub+ to mold & bl[1 etc4 ,! tea*] demon/rates v>i\s exp]im5ts f "t to "t to %[ ! *ildr5 :at c be done ) ^! ?+s1 b ! *ildr5 are left free to inve/igate to _! he>t's cont5t4 ,!re is no tea*+ 9 ?is introductory c\rse o!r ?an brief answ]s to que/ions4 ,! a/ronomy & geology read+ usually accompany ! "w 9 introductory sci5ce4 ,,ackn[l$gm5ts ,to ,fr$]ic ,burk1 presid5t ( ! ,san ,francisco ,/ate ,normal ,s*ool1 ,i am mo/ "u obligation 9 connection ) ! prep>ation ( ?is book4 ,8 ideas inspir$ x1 & 8 dynamic criticism did mu* t[>d %ap+ x4 ,my wife1 ,heluiz ,*&l] ,wa%burne1 gave invaluable help ?r\gh\t ! "w1 especially 9 ! pres5t revision ( ! c\rse4 ,"o ( my co-work]s on ! ,normal ,s*ool faculty1 ,miss ,l\ise ,mohr1 r5d]$ mu* assi/ance 9 ! classification & selection ( inf]5ces4 ,miss ,beatrice ,h>p] assi/$ 9 ! prep>ation ( ! tables ( supplies & app>atus1 publi%$ 9 ! manual to accompany ?is book4 ,& ,i wi% to ?ank ! *ildr5 ( ! ,normal ,s*ool = _! pati5ce & coop]ation 9 pos+ = ! photographs4 ,! photographs are by ,joseph ,m>ron4 ,,cont5ts ,,*apt] ,,page #a4 ,,gravitation #a #a4 ,a real place :]e ?+s weigh no?+ & :]e !re is no up or d[n #a #b4 ,wat] seeks its own level #f #c4 ,! sea ( compress$ air 9 :i* we live3 ,air pressure #aj #d4 ,s9k+ & float+3 ,displacem5t #bc #e4 ,h[ ?+s are kept f toppl+ ov]3 ,/ability #bi #b4 ,,molecul> ,,attraction #cf #f4 ,h[ liquids are absorb$3 ,capill>y attraction #cf #g4 ,h[ ?+s /ick to "o ano!r3 ,adhesion #da #h4 ,! =ce t makes a ?+ hold toge!r3 ,cohesion #dd #i4 ,friction #di #c4 ,,cons]vation ,,( ,,en]gy #eg #aj4 ,lev]s #eg #aa4 ,in]tia #ff #ab4 ,c5trifugal =ce #gb #ac4 ,action & reaction #gg #ad4 ,ela/icity #hb #d4 ,,heat #hh #ae4 ,heat makes ?+s exp& #hh #af4 ,cool+ f expansion #id #ag4 ,freez+ & melt+ #if #ah4 ,evaporation #ajj #ai4 ,boil+ & cond5s+ #ajg #bj4 ,conduction ( heat & convection #aaf #e4 ,,radiant ,,heat ,,& ,,light #abb #ba4 ,h[ heat gets "h f ! sun2 :y ?+s gl[ :5 !y become v hot #abb #bb4 ,reflection #abi #bc4 ,! b5d+ ( light3 ,refraction #acf #bd4 ,focus #adb #be4 ,magnification #aej #bf4 ,scatt]+ ( light3 ,diffusion ( light #aeh #bg4 ,color #afa #f4 ,,s\nd #agd #bh4 ,:at s\nd is #agd #bi4 ,e*oes #ahc #cj4 ,pit* #ahe #g4 ,,magnetism ,,& ,,electricity #aij #ca4 ,magnets2 ! compass #aij #cb4 ,/atic electricity #aif #h4 ,,electricity #bjc #cc4 ,mak+ electricity fl[ #bjc #cd4 ,conduction ( electricity #bac #ce4 ,complete circuits #bai #cf4 ,gr\nd$ circuits #bbe #cg4 ,resi/ance #bbi #ch4 ,! electric arc #bcc #ci4 ,%ort circuits & fuses #bdj #dj4 ,electromagnets #bdg #i4 ,,m+l+ ,,( ,,molecules #bei #da4 ,solutions & emulsions #bei #db4 ,cry/als #bfe #dc4 ,diffusion #bfh #dd4 ,cl\ds1 ra91 & dew3 ,humidity #bgd #de4 ,s(t5+ due to oil or wat] #bij #aj4 ,,*emical ,,*ange ,,& ,,en]gy #bic #df4 ,:at ?+s are made (3 ,elem5ts #bic #dg4 ,burn+3 ,oxidation #cab #dh4 ,*emical *ange caus$ by heat #cbc #di4 ,*emical *ange caus$ by light #cbf #ej4 ,*emical *ange caus$ by electricity #cce #ea4 ,*emical *ange releases en]gy #cdj #eb4 ,explosions #cdb #aa4 ,,solution ,,& ,,*emical ,,action #cdi #ec4 ,*emical *ange help$ by solution #cdi #ed4 ,acids #cea #ee4 ,bases #cee #ef4 ,neutralization #cfj #eg4 ,eff]vesc5ce #cfe #ab4 ,,analysis #cgj #eh4 ,analysis #cgj ,,app5dixes3 ,a4 ,! ,electrical ,app>atus #cgi ,b4 ,con/ruction ( ! ,cig>-box ,telegraph #cha ,,index #chc ,,common ,,sci5ce ,,*apt] ,,"o ,,gravitation ,,section #a4 ,a real place :]e ?+s weigh no?+ & :]e !re is no up or d[n4 ,:y is x t ! oceans d n fl[ (f ! e>?8 ,:at is gravity8 ,:at is d[n1 & :at is up8 ,!re is a place :]e no?+ has weight2 :]e !re is no up or d[n2 :]e no?+ ev] falls2 & :]e1 if p 7 !re1 !y w\ld float ab\t ) _! heads po9t+ 9 all directions4 ,?is is n a fairy tale2 e ^w ( x is sci5tifically true4 ,if we _h "s way ( fly+ /raight t[>d ! sun ab\t #afj1jjj miles1 we %\ld really rea* ?is /range place4 ,let u pret5d t we c d x4 ,suppose we h built a ma*9e t c fly f> out f ! e>? ?r\gh space 7( c\rse no "o has really ev] inv5t$ su* a ma*9e74 ,& s9ce ! place is f> beyond ! air t surr\nds ! e>?1 let u imag9e t we h fitt$ out ! air-tight cab9 ( our ma*9e ) pl5ty ( air to brea!1 & ) food & ev]y?+ we ne$ = liv+4 ,we %all picture x some?+ l ! cab9 ( an ocean /eam]4 ,& let u pret5d t we h j arriv$ at ! place :]e ?+s weigh no?+3 ,:5 y try to walk1 y glide t[>d ! ceil+ ( ! cab9 & d n /op be=e y\r head bumps aga9/ x4 ,if y pu% on ! ceil+1 y float back t[>d ! floor4 ,b y _c tell :e!r ! floor is above or bel[1 because y h no idea z to :i* way is up & :i* way is d[n4 ,z a matt] ( fact !re is no up or d[n4 ,y discov] ?is quickly en\gh :5 y try to p\r a glass ( wat]4 ,y d n "k :]e to hold ! glass or :]e to hold ! pit*]4 ,no matt] h[ y hold !m1 ! wat] w n p\r--po9t ! top ( ! pit*] t[>d ! ceil+1 or ! floor1 or ! wall1 x makes no diff]5ce4 ,f9ally y h to put y\r h& into ! pit*] & pull ! wat] out4 ,x comes4 ,n a drop runs betwe5 y\r f+]s--:i* way c x run1 s9ce !re is no d[n8 ,! big lump ( wat] /ays "r on y\r h&4 ,?is surprises y s mu* t y let g ( ! pit*]4 ,nev] m9d2 ! pit*] /ays pois$ 9 mid-air4 ,b h[ are y go+ to get a dr9k8 ,x does n seem reasonable to try to dr9k a l>ge lump ( wat]4 ,yet :5 y hold ! lump to y\r lips & suck x y c draw ! wat] into y\r m\?1 & x is z wet z ev]2 !n y c =ce x on d[n to 7or r t[>d7 y\r ?roat ) y\r tongue4 ,/ill y h left 9 y\r h& a big piece ( wat] t w n fl[ (f4 ,y ?r[ x away1 & x sails ?r\gh ! air ( ! cab9 9 a /raight l9e until x spla%es aga9/ ! wall4 ,x wets ! wall z mu* z wat] on ! e>? w\ld1 b x does n run (f4 ,x /icks !re1 l a spla%-%ap$ piece ( cle>1 colorless gelat94 ,suppose t = ! sake ( exp]im5t+ y h br\ght an elephant along on ?is trip4 ,y c move "u him 7or ov] him--anyway betwe5 him & ! floor71 brace y\r feet on ! floor1 & give him a pu%4 7,if he happ5s to /ep on y\r toes :ile y are do+ ?is1 y d n m9d 9 ! lea/1 because he does n weigh any?+1 y "k47 ,if y pu% h>d en\gh to get ! elephant />t$1 he rises sl[ly t[>d ! ceil+4 ,:5 he objects on ! way1 & /ruggles & kicks & tries to get back to ! floor1 x does n help him at all4 ,8 bulky1 kick+ body floats /eadily on till x cra%es into ! ceil+4 ,no *airs or b$s are ne$$ 9 ?is place4 ,y c lie or sit 9 mid-air1 or cl+ to a fixture on a wall1 re/+ z g5tly !re z a fea!r might4 ,!re is no ne$ to set ! table = meals--j lay ! di%es ) ! food on !m 9 space & !y /ay !re4 ,if ! top ( y\r cup ( *ocolate is t[>d ! ceil+1 & y\r plate ( food is turn$ ! o!r way1 no h>m is done4 ,y\r feet may happ5 to po9t t[>d ! ceil+1 :ile "s "o else's po9t t[>d ! floor1 z y sit 9 mid-air1 eat+4 ,!re is "s difficulty 9 gett+ ! food on ! di%es1 s probably y d n wi% to bo!r ) di%es1 aft] all4 ,d y want "s ma%$ potatoes8 ,all "r1 "h x is--& ! cook j]ks ! spoon away f ! potatoes1 leav+ !m float+ be=e y1 ready to eat4 ,x is lit]ally a topsy-turvy place4 ,d y want to "k :y all ?is w\ld happ58 ,"h is ! reason3 ,!re is a great =ce kn[n z gravitation4 ,x is ! pull t ev]y?+ 9 ! univ]se has on ev]y?+ else4 ,! m massive a ?+ is1 ! m gravitational pull x has on o!r objects2 b ! f>!r ap>t ?+s are1 ! less pull !y h on ea* o!r4 ,! e>? is v massive1 & we live "r on its surface2 s x pulls u /rongly t[>d x4 ,!re=e we say t we weigh some?+4 ,& s9ce e "t we roll (f a b$1 = in/ance1 or jump (f a *air1 ! e>? pulls u swiftly t[>d x1 we say t ! e>? is d[n4 ,d[n simply means t[>d ! ?+ t is pull+ u4 ,if we 7 on ! surface ( ! moon1 ! moon w\ld pull u4 ,d[n w\ld !n be "u our feet or t[>d ! c5t] ( ! moon1 & ! e>? w\ld be se5 float+ up 9 ! sky4 ,= up means away f ! ?+ :i* is pull+ u4 ,,:y ,,wat] ,,does ,,n ,,fl[ ,,(f ,,! ,,e>?4 ,x 0 because p did n "k ab\t gravitation t !y laugh$ at ,columbus :5 he said ! e>? 0 r\nd4 ,:y1 if ! e>? 7 r\nd1 !y argu$1 ! wat] w\ld all fl[ (f on ! o!r side4 ,!y did n "k t wat] fl[s d[nhill because ! e>? is pull+ x t[>d its c5t] by gravitation1 & t x does n make ! slighte/ diff]5ce on :i* side ( ! e>? wat] is1 s9ce x is /ill pull$ t[>d ! c5t]4 ,,:y ,,! ,,_w ,,does ,,n ,,fall ,,d[n4 ,& p us$ to wond] :at held ! e>? up4 ,! answ]1 z y c see1 is easy4 ,!re simply is no up or d[n 9 space4 ,! e>? _c fall d[n1 because !re is no d[n to fall to4 ,d[n m]ely means t[>d ! e>?1 & ! e>? _c v well fall t[>d itself1 c x8 ,! sun is pull+ on x1 ?\gh2 s ! e>? c\ld fall into ! sun1 & x w\ld d s1 if x 7 n sw++ ar\nd ! sun s fa/4 ,y w see h[ ?is keeps x f fall+ into ! sun :5 y come to ! section on c5trifugal =ce4 ,,:y ,,!re ,,is ,a ,,place ,,:]e ,,?+s ,,weigh ,,no?+4 ,n[ ab\t ! place :]e gravitation has no effect4 ,s9ce an object ne> ! sun is pull$ m by ! sun ?an x is by ! e>?1 & s9ce d[n "h ne> ! e>? an object is pull$ h>d] by ! e>? ?an by ! sun1 x is cle> t !re mu/ be a place betwe5 ! sun & ! e>? :]e _! pulls j balance2 & :]e ! sun pulls j z h>d "o way z ! e>? pulls ! o!r way1 ?+s w n fall ei!r way1 b w float4 ,! place :]e ! pulls ( ! sun & ! e>? are equal is n halfway betwe5 ! e>? & ! sun1 because ! sun is s mu* l>g] & pulls s mu* m p[]fully ?an ! e>?1 t ! place :]e _! pulls balance is mu* ne>] ! e>? ?an x is to ! sun4 ,z a matt] ( fact1 x c be easily calculat$ t ?is spot is some:]e ne> #afj1jjj miles f ! e>?4 ,!re are o!r spots l x betwe5 e two />s1 & 9 ! c5t] ( ! e>?1 & 9 ! c5t] ( e o!r body4 ,y see1 9 ! c5t] ( ! e>? !re is j z mu* ( ! e>? pull+ "o way z !re is pull+ ! o!r1 s aga9 !re is no up or d[n4 ,,application #a4 ,expla9 :y ! p on ! o!r side ( ! e>? d n fall (f2 :y y h weight2 :y riv]s run d[nhill2 :y ! _w does n fall d[n4 ,,section #b4 ,wat] seeks its own level4 ,:y does a spr+ bubble up f ! gr\nd8 ,:at makes ! wat] come up ?r\gh ! pipe into y\r h\se8 ,:y is a fire eng9e ne$$ to pump wat] up high8 ,y rememb] t up :]e ! pull ( ! e>? & ! sun balance ea* o!r1 wat] c\ld n fl[ or flatt5 out4 ,let u try to imag9e t wat]1 "h on ! e>?1 has lo/ its habit ( flatt5+ out :5ev] possible--t1 l clay1 x keeps :atev] %ape x is giv54 ,fir/ y notice t ! wat] fails to run out ( ! faucets4 7,= 9 mo/ places 9 ! _w z x really is1 ! wat] t comes ?r\gh faucets is simply fl[+ d[n f "s high res]voir47 ,p all beg9 to se>* = wat] to dr9k4 ,!y ru% to ! riv]s & beg9 to dig ! wat] out ( !m4 ,x looks que] to see a hole left 9 ! wat] :]ev] a p]son has scoop$ up a pailful4 ,if "s "o slips into ! riv] :ile gett+ wat]1 he does n dr[n1 because ! wat] _c close 9 ov] 8 head2 !re is j a deep hole :]e he has fall5 ?r\gh1 & he brea!s ! air t comes d[n to him at ! bottom ( ! hole4 ,if y try to r[ on ! wat]1 ea* /roke ( ! o>s piles up ! wat]1 & ! boat makes a deep furr[ :]ev] x goes s t ! :ole riv] beg9s to look l a r\gh1 pl[$ field4 ,:5 ! riv]s are us$ up1 p se>* 9 va9 = spr+s4 7,no spr+s c\ld fl[ 9 our ev]yday _w if wat] did n seek its own level2 = ! wat]s ( ! spr+s come f hills or m\nta9s1 & ! high] wat]1 9 try+ to flatt5 out1 =ces ! l[] wat] up ?r\gh ! gr\nd on ! hillsides or 9 ! valleys47 ,s p h to get _! wat] f und]gr\nd or g to lakes = x4 ,& ^! lakes are /range sights4 ,/orms toss up huge waves1 :i* rema9 z ridges & furr[s until ano!r /orm te>s !m d[n & ?r[s up new ones4 ,b ) no riv]s fl[+ into !m1 ! lakes also are us$ up 9 "t4 ,! only fre% wat] to be _h is :at is caught f ! ra94 ,ev5 wells soon become useless2 because z soon z y pump up ! wat] surr\nd+ ! pump1 no m wat] fl[s 9 ar\nd x2 & if y use a bucket to raise ! wat]1 ! well goes dry z soon z ! supply ( wat] /&+ 9 x has be5 drawn4 ,y w und]/& m ab\t wat] seek+ its own level if y d ?is exp]im5t3 ,,exp]im5t #a4 ,put "o end ( a rubb] tube ov] ! n>r[ neck ( a funnel 7a glass funnel is be/71 & put ! o!r end ( ! tube ov] a piece ( glass tub+ n less ?an #e or #f in*es long4 ,hold up ! glass tube & ! funnel1 lett+ ! rubb] tube sag d[n betwe5 !m z 9 ,figure #a4 ,n[ fill ! funnel ?ree f\r?s full ( wat]4 ,raise ! glass tube high] if ! wat] />ts to fl[ out ( x4 ,if no wat] %[s 9 ! glass tube1 l[] x until x does4 ,gradually raise & l[] ! tube1 & notice h[ high ! wat] goes 9 x :5ev] x is held /ill4 ,?is same ?+ w\ld happ5 ) any %ape ( tube or funnel4 ,y h ano!r example ( x :5 y fill a teakettle3 ! wat] rises 9 ! sp\t j z high z x does 9 ! kettle4 ,illu/ration3 ,,fig4 #a4 ,! wat] 9 ! tube rises to ! level ( ! wat] 9 ! funnel4 ,,:y ,,wat] ,,fl[s ,,up ,,into ,,y\r ,,h\se4 ,x is because wat] seeks its own level t x comes up ?r\gh ! pipes 9 y\r h\se4 ,usually ! wat] = a city is pump$ into a res]voir t is z high z ! highe/ h\se 9 ! city4 ,:5 x fl[s d[n f ! res]voir1 x t5ds to rise 9 any pipe ?r\gh :i* x fl[s1 to ! height at :i* ! wat] 9 ! res]voir /&s4 ,if a h\se is high] ?an ! surface ( ! wat] 9 ! res]voir1 ( c\rse t h\se w get no runn+ wat]4 ,,:y ,,fire ,,eng9es ,,are ,,ne$$ ,,to ,,=ce ,,wat] ,,high4 ,9 putt+ out a fire1 ! firem5 (t5 want to ?r[ ! wat] ) a good deal ( =ce4 ,! t5d5cy ( ! wat] to seek its own level does n always give a high en\gh or p[]ful en\gh /ream f ! fire hose2 s a fire eng9e is us$ to pump ! wat] ?r\gh ! hose1 & ! /ream fl[s ) mu* m =ce ?an if x 7 n pump$4 ,,application #b4 ,a4 ,c4 ,:eel] ( ,*icago b\ght a little f>m 9 ,indiana1 & _h a w9dmill put up to supply ! place ) wat]4 ,b at fir/ he 0 n sure :]e he %\ld put ! tank into :i* ! w9dmill 0 to pump ! wat] & f :i* ! wat] %\ld fl[ into ! kit*51 ba?room1 & b>n4 ,! b>n 0 on a knoll1 s t its floor 0 almo/ z high z ! ro( ( ! h\se4 ,:i* w\ld h be5 ! be/ place = ! tank3 high up on ! w9dmill 7:i* /ood on ! knoll by ! b>n71 or ! basem5t ( ! h\se1 or ! attic ( ! h\se8 ,illu/ration3 ,,fig4 #b4 ,:]e is ! be/ location = ! tank8 ,,application #c4 ,a man 0 ab\t to op5 a g>age 9 ,san ,francisco4 ,he _h a l>ge oil tank & want$ a simple way ( tell+ at a glance h[ full x 04 ,"o ( 8 workm5 sugge/$ t he atta* a long piece ( glass tub+ to ! side ( ! tank1 connect+ x ) an extra faucet ne> ! bottom ( ! tank4 ,a second workman said1 ,no1 t won't d4 ,y\r tank holds ev] s mu* m ?an ! tube w\ld hold1 s ! oil 9 ! tank w\ld =ce ! oil up ov] ! top ( ! tube1 ev5 :5 ! tank 0 n full4 ,:o 0 "r8 ,illu/ration3 ,,fig4 #c4 ,:5 ! tank is full1 w ! oil ov]fl[ ! top ( ! tube8 ,,section #c4 ,! sea ( compress$ air 9 :i* we live3 ,air pressure4 ,does a balloon explode if x goes high 9 ! air8 ,:at is suction8 ,:y does soda wat] run up a /raw :5 y draw on ! /raw8 ,:y w evaporat$ milk n fl[ freely out ( a c 9 :i* !re is only "o hole8 ,:y does wat] gurgle :5 y p\r x out ( a bottle8 ,we are liv+ 9 a sea ( compress$ air4 ,e squ>e in* ( our bodies has ab\t #ae p\nds ( pressure aga9/ x4 ,! only reason we are n cru%$ is t !re is z /rong pressure inside ( our bodies pu%+ out z !re is outside pu%+ 94 ,!re is compress$ air 9 ! blood & all ?r\gh ! body4 ,if y 7 to lie d[n on ! gr\nd & h all ! air pump$ out f "u y1 ! air above w\ld cru% y z flat z a pancake4 ,y might z well let a doz5 big f>m horses trample on y1 or let a huge elephant roll ov] y1 z let ! air press d[n on y if !re 7 no air und]nea? & inside y\r body to resi/ ! pressure f above4 ,x is h>d to believe t ! air & liquids 9 our bodies are press+ out ) a =ce great en\gh to resi/ ?is cru%+ weight ( air4 ,b if y 7 sudd5ly to g up above ! e>?'s atmosph]e1 or if y 7 to /ay d[n "h & g into a room f :i* ! air 7 to be pump$ all at once1 y\r body w\ld explode l a torp$o4 ,:5 y suck ! air out ( a bottle1 ! surr\nd+ air pressure =ces ! bottle aga9/ y\r tongue2 if ! bottle is a small "o1 x w /ick !re4 ,& ! pressure ( ! air & blood 9 y\r tongue w =ce y\r tongue d[n into ! neck ( ! bottle f :i* "p ( ! air has be5 tak54 ,9 ! same way1 :5 y =ce ! air out ( a rubb] suction cap1 su* z is us$ to fa/5 read+ lamps to ! head ( a b$1 ! air pressure outside holds ! suction cap tightly to ! object aga9/ :i* y fir/ press$ x1 mak+ x /ick !re4 ,we c easily exp]im5t ) air pressure because we c get almo/ entirely rid ( x 9 places & c !n wat* :at happ5s4 ,a place f :i* ! air is practically all pump$ out is call$ a vacuum4 ,"h are "s int]e/+ exp]im5ts t w %[ :at air pressure does3 ,illu/ration3 ,,fig4 #d4 ,:5 ! po9t is knock$ (f ! electric lamp1 ! wat] is =c$ into ! vacuum4 ,,exp]im5t #b4 ,hold a burn$-out electric lamp 9 a bas9 ( wat]1 break its po9t (f1 & see :at happ5s4 ,all ! common electric lamps 7less ?an #gj watts7 are made ) vacuums inside4 ,! reason = ?is is t ! f9e wire w\ld burn up if !re 7 any air 9 ! lamps4 ,:5 y knock ! po9t (f ! globe1 x leaves a space into :i* ! wat] c be pu%$4 ,s9ce ! air is press+ h>d on ! surface ( ! wat] except 9 ! "o place :]e ! vacuum 9 ! lamp globe is1 ! wat] is =c$ viol5tly into ?is empty space4 ,x really is a good deal l ! way mud comes up betwe5 y\r toes :5 y are b>efoot4 ,y\r foot is press+ on ! mud all ar\nd except 9 ! spaces betwe5 y\r toes1 & s ! mud is =c$ up into ^! spaces4 ,! air pressure on ! wat] is l y\r foot on ! mud1 & ! space 9 ! lamp globe is l ! space betwe5 y\r toes4 ,s9ce :]ev] !re is air x is press+ h>d1 ! only space into :i* x c =ce wat] or any?+ else is into a place f :i* all ! air has be5 remov$1 l ! inside ( ! lamp globe4 ,! reason t ! wat] does n run out ( ! globe is ?is3 ! hole is too small to let ! air squeeze up pa/ ! wat]1 & !re=e no air c take ! place ( ! wat] t might o!rwise run out4 ,9 ord] to fl[ out1 !n1 ! wat] w\ld h to leave an empty space or vacuum beh9d x1 & ! air pressure w\ld n all[ ?is4 ,,:y ,,wat] ,,gurgles ,,:5 ,,x ,,p\rs ,,out ,,( ,a ,,bottle4 ,y h (t5 notic$ t :5 y p\r wat] out ( a bottle x gurgles & gulps in/ead ( fl[+ out ev5ly4 ,! reason = ?is is t :5 a little wat] gets out & leaves an empty space beh9d1 ! air pu%+ aga9/ ! wat] />ts to =ce x back up2 b s9ce ! m\? ( ! bottle is fairly wide1 ! air itself squeezes pa/ ! wat] & bubbles up to ! top4 ,,exp]im5t #c4 ,put a /raw or a piece ( glass tube d[n into a glass ( wat]4 ,hold y\r f+] tightly ov] ! upp] end1 & lift ! tube out ( ! wat]4 ,notice h[ ! wat] /ays 9 ! tube4 ,n[ remove y\r f+] f ! upp] end4 ,! air holds ! wat] up 9 ! tube because !re is no room = x to bubble up into ! tube to take ! place ( ! wat]2 & ! wat]1 to fl[ out ( ! tube1 w\ld h to leave a vacuum1 :i* ! air outside does n all[4 ,b :5 y take y\r f+] (f ! top ( ! /raw or tube1 ! air f above takes ! place ( ! wat] z rapidly z x fl[s out2 s !re is no t5d5cy to =m a vacuum1 & ! wat] leaves ! tube4 ,n[ d y see :y y make two holes 9 ! top ( a c ( evaporat$ milk :5 y wi% to p\r ! milk out ev5ly8 ,illu/ration3 ,,fig4 #e4 ,! wat] is held 9 ! tube by air pressure4 ,,exp]im5t #d4 ,pu% a rubb] suction cap firmly aga9/ ! inside ( ! bell j> ( an air pump4 ,try to pull ! suction cap (f4 ,if x comes (f1 press x on aga92 place ! bell j> on ! plate ( ! air pump1 & pump ! air out ( ! j>4 ,:at mu/ h be5 hold+ ! suction cap aga9/ ! inside ( ! j>8 ,does air press up & sidewise z well z d[n8 ,te/ ?is fur!r 9 ! foll[+ exp]im5t3 ,illu/ration3 ,,fig4 #f4 ,an air pump4 ,,exp]im5t #e4 ,put a cork into an empty bottle4 ,d n use a new cork1 b "o t has be5 fitt$ into ! bottle _m times & has become %ap$ to ! neck4 ,press ! cork 9 r firmly1 s t x is air-tight1 b d n jam x 94 ,set ! bottle on ! plate ( ! air pump1 put ! bell j> ov] x1 & pump ! air out ( ! j>4 ,:at makes ! cork fly out ( ! bottle8 ,:at 0 really 9 ! empty bottle8 ,:y c\ld x n pu% ! cork out until y _h pump$ ! air out ( ! j>8 ,,exp]im5t #f4 ,wax ! rims ( ! two ,magdeburg hemisph]es 7see ,fig4 #g74 ,screw ! l[] section into ! hole 9 ! plate ( ! air pump4 ,be sure t ! /op valve 9 ! neck ( ! hemisph]e is op54 7,! little h&le %\ld be v]tical47 ,fit ! o!r section on to ! fir/1 & pump out z mu* air z y c4 ,close ! /op valve4 ,unscrew ! hemisph]es f ! air pump4 ,try to pull !m ap>t--pull /raight out1 tak+ c>e n to slide ! p>ts4 ,if y wi%1 let "s "o else take "o h&le1 & see if ! two ( y c pull x ap>t4 ,illu/ration3 ,,fig4 #g4 ,! exp]im5t ) ! ,magdeburg hemisph]es4 ,be=e y pump$ ! air out ( ! hemisph]e1 ! compress$ air inside ( !m 7y rememb] all ! air d[n "h is compress$7 0 pu%+ !m ap>t j z h>d z ! air outside ( !m 0 pu%+ !m toge!r4 ,:5 y pump$ ! air out1 h[ev]1 !re 0 h>dly any air left inside ( !m to pu% outw>d4 ,s ! /rong pressure ( ! outside air aga9/ ! hemisph]es _h no?+ to oppose x4 ,x !re=e press$ !m v tightly toge!r & held !m t way4 ,?is exp]im5t 0 fir/ tri$ by a man liv+ 9 ,magdeburg1 ,g]many4 ,! fir/ set ( hemisph]es he us$ prov$ too weak1 & :5 ! air 9 !m 0 p>tly pump$ out1 ! pressure ( ! outside air cru%$ !m l an egg %ell4 ,! second set 0 ov] a foot 9 diamet] & mu* /rong]4 ,aft] he _h pump$ ! air out1 x took sixte5 horses1 eight pull+ "o way & eight ! opposite way1 to pull ! hemisph]es ap>t4 ,,exp]im5t #g4 ,fill a bottle 7or flask7 half full ( wat]4 ,?r\gh a "o-hole /opp] t w fit ! bottle1 put a b5t piece ( glass tub+ t w rea* d[n to ! bottom ( ! bottle4 ,set ! bottle1 ?us /opp]$1 on ! plate ( ! air pump1 ) a beak] or tumbl] "u ! out] end ( ! glass tube4 ,put ! bell j> ov] ! bottle & glass1 & pump ! air out ( ! j>4 ,:at is x t =ces ! wat] up & out ( ! bottle8 ,:y c\ld x d ?is :5 ! air 0 pump$ out ( ! bell j> & n be=e8 ,,h[ ,a ,,seltz] ,,siphon ,,works4 ,a seltz] siphon works on ! same pr9ciple4 ,b in/ead ( ! ord9>y compress$ air t is all ar\nd u1 !re is 9 ! seltz] siphon a gas 7c>bon dioxid7 :i* has be5 mu* m compress$ ?an ord9>y air4 ,?is /rongly compress$ gas =ces ! seltz] wat] out into ! less compress$ air1 exactly z ! compress$ air 9 ! upp] "p ( ! bottle =c$ ! wat] out into ! comp>ative vacuum ( ! bell j> 9 ,exp]im5t #g4 ,,exp]im5t #h4 ,fill a toy balloon p>tly full ( air by bl[+ into x1 & close ! neck ) a rubb] b& s t no air c escape4 ,lay a sauc] ov] ! hole 9 ! plate ( ! air pump1 s t ! rubb] ( ! balloon _c be suck$ d[n ! hole4 ,lay ! balloon on top ( ?is sauc]1 put ! bell j> ov] x1 & pump ! air out ( ! j>4 ,:at makes ! balloon exp&8 ,:at is 9 x8 ,:y c\ld x n exp& be=e y pump$ ! air out f ar\nd x8 ,a toy balloon exp&s = ! same reason :5 x goes high 9 ! air4 ,up !re ! air pressure is n s /rong outside ! balloon1 & s ! gas inside makes ! balloon exp& until x bur/s4 ,illu/ration3 ,,fig4 #h4 ,a siphon4 ,! air pu%es ! wat] ov] ! side ( ! pan4 ,,exp]im5t #i4 ,lay a rubb] tube flat 9 ! bottom ( a pan ( wat]1 s t ! tube w be fill$ ) wat]4 ,let "o end /ay "u wat]1 b p9* ! o!r end tightly %ut ) y\r ?umb & f+] & lift x out ( ! pan4 ,l[] ?is clos$ end into a s9k or empty pan t is l[] ?an ! pan ( wat]4 ,n[ /op p9*+ ! tube %ut4 ,?is device is call$ a siphon 7,fig4 #h74 ,,exp]im5t #aj4 ,put ! m\? ( a small syr+e1 or bett]1 ( a glass model lift pump1 "u wat]4 ,draw ! h&le up4 ,does ! wat] foll[ ! plung] up1 /& /ill1 or g d[n 9 ! pump8 ,:5 y pull up ! plung]1 y leave an empty space2 y %ove ! air out ( ! pump or syr+e ahead ( ! plung]4 ,! air outside1 press+ on ! wat]1 =ces x up into ?is empty space f :i* ! air has be5 pu%$4 ,b air pressure _c =ce wat] up ev5 into a p]fect vacuum f>!r ?an ab\t #cc feet4 ,if y\r glass pump 71 say1 #dj feet long1 ! wat] w\ld foll[ ! plung] up = a little ov] #cj feet1 b no?+ c\ld suck x high]2 = by ! "t x rea*es t height x is pu%+ d[n ) its own weight z h>d z ! air is press+ on ! wat] bel[4 ,no suction pump1 or siphon1 h[ev] p]fect1 w ev] lift wat] m ?an ab\t #cc feet1 & x w d well if x draws wat] up #bh or #cj feet4 ,?is is because a p]fect vacuum _c be made4 ,!re is always "s wat] vapor =m$ by ! wat] evaporat+ a little1 & !re is always a small am\nt ( air t has be5 dissolv$ 9 wat]1 bo? ( :i* p>tly fill ! space above ! wat] & press d[n a little on ! wat] )9 ! pump4 ,illu/ration3 ,,fig4 #i4 ,a glass model suction pump4 ,if y _h a /raw ov] #cc feet long1 & if "s "o held a glass ( lemonade = y d[n ne> ! sidewalk :ile y lean$ ov] f ! ro( ( a ?ree-/ory build+ ) y\r long /raw1 y c\ld n possibly dr9k ! lemonade4 ,! air pressure w\ld n be great en\gh to lift x s high1 no matt] h[ h>d y suck$1--t is1 no matt] h[ p]fect a vacuum y made 9 ! upp] "p ( ! /raw4 ,! lemonade w\ld rise "p way1 & !n y\r /raw w\ld be flatt5$ by ! pressure outside4 ,"s days ! air c =ce wat] up f>!r 9 a tube ?an x c on o!r days4 ,if x c =ce ! wat] up #cc feet today1 x w p]haps be able to =ce x up only #cj feet imm$iately be=e a /orm4 ,& if x =ces wat] up #cc feet at sea level1 x may =ce x up only #ae or #bj feet on a high m\nta91 = on a m\nta9 !re is mu* less air above to make pressure4 ,! pressure ( ! air is diff]5t 9 diff]5t places2 :]e ! air is heavy & press+ h>d1 we say ! pressure is high2 :]e ! air is light & n press+ s h>d1 we call ! pressure l[4 ,a place :]e ! air is heavy is call$ an area ( high pressure2 :]e x is light1 an area ( l[ pressure4 7,see ,section #dd47 ,,:at ,,makes ,,w9ds8 ,x is because ! air does n press equally all ! "t & ev]y:]e t we h w9ds4 ,naturally1 if ! air is press+ h>d] 9 "o place ?an 9 ano!r1 ! l[] air w be pu%$ sidewise 9 ! areas ( high pressure & w ru% to ! areas :]e !re is less pressure4 ,& air ru%+ f "o place to ano!r is call$ w9d4 ,illu/ration3 ,,fig4 #aj4 ,,application #d4 ,a man _h two wat] res]voirs1 :i* /ood at ! same level1 "o on ea* side ( a hill4 ,! hill betwe5 !m 0 ab\t #ej feet high4 ,"o res]voir 0 full1 & ! o!r 0 empty4 ,he want$ to get "s ( ! wat] f ! full res]voir into ! empty "o4 ,he did n h a pump to =ce ! wat] f "o to ! o!r1 b he did h a long hose1 & c\ld h b\ght m4 ,8 hose 0 long en\gh to rea* ov] ! top ( ! hill1 b n long en\gh to g ar\nd x4 ,c\ld he h siphon$ ! wat] f "o res]voir to ! o!r8 ,w\ld he h _h to buy m hose8 ,,application #e4 ,two boys 7 out hik+ & 7 v ?ir/y4 ,!y came to a des]t$ f>m & f\nd a deep well2 x 0 ab\t #dj feet d[n to ! wat]4 ,!y _h no pump1 b !re 0 a piece ( hose ab\t #ej feet long4 ,"o boy sugge/$ t !y drop "o end ( ! hose d[n to ! wat] & suck ! wat] up1 b ! o!r said t t w\ld n "w--! only way w\ld be to l[] ! hose into ! wat]1 close ! upp] end1 pull ! hose out & let ! wat] p\r out ( ! l[] end ( ! hose into _! m\?s4 ,a /rang] came pa/ :ile ! boys 7 argu+1 & said t nei!r way w\ld "w2 t al?\gh ! hose 0 long en\gh1 ! wat] 0 too f> d[n to be rais$ 9 ei!r way4 ,he advis$ ! boys to f9d a bucket & to use ! hose z a rope = l[]+ x4 ,:o 0 "r8 ,,inf]5ce ,,ex]cise ,,explanatory ,,note4 ,9 ! inf]5ce ex]cises 9 ?is book1 !re is a gr\p ( facts = y to expla94 ,!y c always be expla9$ by "o or m ( ! pr9ciples /udi$1 l gravitation1 wat] seek+ its own level1 or air pressure4 ,if ask$ to expla9 :y suck+ ?r\gh a /raw makes soda wat] come up into y\r m\?1 = in/ance1 y %\ld n m]ely say air pressure1 b %\ld tell :y y ?9k x is air pressure t causes ! liquid to rise ?r\gh ! /raw4 ,! answ] %\ld be some?+ l ?is3 ,! soda wat] comes up into y\r m\? because ! suck+ takes ! air pressure away f ! top ( ! soda wat] t is 9 ! /raw4 ,?is leaves ! air press+ d[n only on ! surface ( ! soda wat] 9 ! glass4 ,!re=e1 ! air pressure pu%es ! soda wat] up into ! /raw & into y\r m\? :]e ! pressure has be5 remov$ by suck+4 ,sometimes1 :5 y h %[n t y und]/& ! pr9ciples v well1 ! tea*] may let y take a %ort cut & j "n ! pr9ciple1 b ?is w be done only aft] y h prov$ by a numb] ( full answ]s t y ?or\ghly und]/& ea* pr9ciple nam$4 ,"s ( ! foll[+ facts are acc\nt$ = by air pressure2 "s by wat] seek+ its own level2 o!rs by gravitation4 ,see if y c tell :i* ( ! ?ree pr9ciples expla9s ea* fact3 #a4 ,ra9 falls f ! cl\ds4 #b4 ,aft] ra9 has soak$ into ! sides ( m\nta9s x runs und]gr\nd & rises1 at l[] levels1 9 spr+s4 #c4 ,:5 !re are no spr+s ne>1 p raise ! wat] f und]gr\nd ) suction pumps4 #d4 ,z fa/ z ! wat] is pump$ away f ar\nd ! bottom ( a pump1 m wat] fl[s 9 to replace x4 #e4 ,aft] y pump wat] up1 x fl[s d[n into y\r pail f ! sp\t ( ! pump4 #f4 ,y c dr9k lemonade ?r\gh a /raw4 #g4 ,if a lemon se$ /icks to ! bottom ( y\r /raw1 ! /raw flatt5s out :5 y suck4 #h4 ,:5 y pull y\r /raw out to remove ! se$1 !re is no hole left 9 ! lemonade2 x closes "r 9 aft] ! /raw4 #i4 ,if y drop ! se$1 x falls to ! floor4 #aj4 ,if y tip ! glass to dr9k ! lemonade1 ! surface ( ! lemonade does n tip ) ! glass1 b rema9s horizontal4 ,,section #d4 ,s9k+ & float+3 ,displacem5t4 ,:at keeps a balloon up8 ,:at makes an iceb]g float8 ,:y does cork float on ! wat] & :y d heavi] sub/ances s9k8 ,if iron s9ks1 :y d iron %ips n s9k8 ,aga9 let u imag9e ourselves up 9 ! place :]e gravitation has no effect4 ,suppose we lay a nail on ! surface ( a b[l ( wat]4 ,x /ays !re & does n s9k4 ,?is does n seem at all surpris+1 ( c\rse1 s9ce ! nail no long] has weight4 ,b :5 we put a cork 9 ! mid/ ( ! wat]1 x /ays !re in/ead ( float+ to ! surface4 ,?is seems peculi>1 because ! less a ?+ weighs ! m easily x floats4 ,s :5 ! cork weighs no?+ at all1 x seems t x %\ld float bett] ?an ev]4 ,( c\rse !re is "s difficulty 9 decid+ :e!r x ought to float t[>d ! "p ( ! wat] ne>e/ ! floor or t[>d ! "p ne>e/ ! ceil+1 s9ce !re is no up or d[n2 b "o w\ld ?9k t x ought someh[ to get to ! outside ( ! wat] & n /ay exactly 9 ! middle4 ,if put on ! outside1 h[ev]1 x /ays !re z well4 ,a toy balloon1 9 ! same way1 w n g t[>d ei!r ! ceil+ or ! floor1 b j /ays :]e x is put1 no matt] h[ light a gas x is fill$ )4 ,! explanation is z foll[s3 ,= an object to float on ! wat] or 9 ! air1 ! wat] or air mu/ be heavi] ?an ! object4 ,x is ! wat] or air be+ pull$ "u ! object by gravity1 t pu%es x up4 ,!re=e1 if ! air & wat] !mselves weigh$ no?+1 ( c\rse !y w\ld be no heavi] ?an ! balloon or ! cork2 ! air or wat] w\ld !n n be pull$ 9 "u ! balloon or cork by gravity1 & s w\ld n pu% !m up1 or aside4 ,illu/ration3 ,,fig4 #aa4 ,! battle%ip is made ( /eel1 yet x does n s9k4 ,,:y ,,iron ,,%ips ,,float4 ,:5 p fir/ talk$ ab\t build+ iron %ips1 o!rs laugh$ at !m4 ,iron s9ks1 !y said1 & y\r boats w g to ! bottom ( ! sea4 ,if ! boats 7 solid iron ?is w\ld be true1 = iron is c]ta9ly mu* heavi] ?an wat]4 ,b if ! iron is b5t up at ! edges1--z x is 9 a di% pan1--x has to pu% mu* m wat] aside be=e x goes "u ?an x w\ld if x 7 flatt5$ out4 ,! wat] displac$1 or pu%$ aside1 w\ld h to take up z mu* room z 0 tak5 up by ! pan & all ! empty space inside ( x1 be=e ! edge w\ld g "u4 ,naturally ?is am\nt ( wat] w\ld weigh a great deal m ?an ! empty pan4 ,b suppose y %\ld fill ! di% pan ) wat]1 or suppose x leak$ full4 ,!n y w\ld h ! weight ( all ! wat] 9 x add$ to ! weight ( ! pan1 & t w\ld be heavy en\gh to pu% aside ! wat] 9 :i* x 0 float+ & let ! pan s9k4 ,?is is :y a %ip sometimes s9ks :5 x spr+s a leak4 ,y may be able to see m cle>ly :y an iron %ip floats by ?is example3 ,suppose y\r iron %ip weighs #fjjj tons & t ! c>go & crew weigh ano!r #ajjj tons4 ,! :ole ?+1 !n1 weighs #gjjj tons4 ,n[ t %ip is a big1 bulky affair & takes up m space ?an #gjjj tons ( wat] does4 ,z x settles into ! wat] x pu%es a great deal ( wat] out ( ! way1 & aft] x s9ks a c]ta9 di/ance x has pu%$ #gjjj tons ( wat] out ( ! way4 ,s9ce ! %ip weighs only #gjjj tons1 x evid5tly _c pu% aside m ?an t weight ( wat]2 s "p ( ! %ip /ays above ! wat]1 & all !re is left = x to d is to float4 ,if ! %ip %\ld freeze solid 9 ! wat] :]e x float$ & !n c\ld be lift$ out ( ! ice by a huge d]rick1 y w\ld f9d t y c\ld p\r exactly #gjjj tons ( wat] into ! hole :]e ! %ip _h be54 ,b if y built y\r %ip ) s little air space 9 x t x took less room ?an #gjjj tons ( wat] takes1 x c\ld g cle> "u ! wat] )\t pu%+ #gjjj tons ( wat] aside4 ,!re=e a %ip ( ?is k9d w\ld s9k4 ,! e>?'s gravity is pull+ on ! %ip & on ! wat]4 ,if ! %ip has displac$ 7pu%$ aside7 its own weight ( wat]1 gravity is pull+ d[n on ! wat] z h>d z x is on ! %ip2 s ! %ip _c pu% any m wat] aside1 & if !re is en\gh air space 9 x1 ! %ip floats4 ,p]haps ! easie/ way to say x is l ?is3 ,any?+ t is light] ?an ! same volume ( wat] w float2 s9ce a cubic foot ( wood weighs less ?an a cubic foot ( wat]1 ! wood w float2 s9ce a qu>t ( oil is light] ?an a qu>t ( wat]1 ! oil w float2 s9ce a p9t ( cream is light] ?an a p9t ( milk1 ! cream w rise4 ,9 ! same way1 any?+ t is light] ?an ! same volume ( air w be pu%$ up by ! air4 ,:5 a balloon ) its pass5g]s weighs less ?an ! am\nt ( air t x takes ! place ( at any "o "t1 x w g up4 ,s9ce a qu>t ( w>m air weighs less ?an a qu>t ( cold air1 ! w>m air w rise4 ,y c see h[ a heavy sub/ance l wat] pu%es a light] "o1 l oil1 up out ( its way1 9 ! foll[+ exp]im5t3 ,,exp]im5t #aa4 ,fill "o te/ tube to ! brim ) k]os5e slightly color$ ) a little iod9e4 ,fill ano!r te/ tube to ! brim ) wat]1 color$ ) a little blue+4 ,put a small squ>e ( c>dbo>d ov] ! te/ tube ( wat]1 hold x 9 place1 & turn ! te/ tube upside d[n4 ,y c let g ( ! c>dbo>d n[1 z ! air pressure w hold x up4 ,put ! m\? ( ! te/ tube ( wat] exactly ov] ! m\? ( ! te/ tube ( k]os5e4 ,pull ! c>dbo>d out f betwe5 ! two tubes1 or h "s "o else d ?is :ile y hold ! two tubes m\? to m\?4 ,if y are c>eful1 y w n spill a drop4 ,if no?+ happ5s :5 ! c>dbo>d is pull$ away1 g5tly rock ! two tubes1 hold+ _! m\?s tightly toge!r4 ,illu/ration3 ,,fig4 #ab4 ,! upp] tube is fill$ ) wat] & ! l[] ) oil4 ,:at w happ5 :5 %e pulls ! c>dbo>d out8 ,oil is light] ?an wat]1 z y "k1 because y h se5 a film ( oil float+ on wat]4 ,:5 y h ! two te/ tubes 9 su* a position t ! oil & wat] c *ange1 ! wat] is pull$ d[n "u ! k]os5e because gravity is pull+ h>d] on ! wat] ?an x is pull+ on ! k]os5e4 ,! wat]1 !re=e1 goes to ! bottom & ?is =ces ! k]os5e up4 ,,application #f4 ,?ree m5 7 mak+ a raft4 ,= floats !y meant to use "s air-tight galvaniz$ iron cyl9d]s4 ,"o ( !m want$ to fill ! cyl9d]s ) cork1 because1 he said1 cork is :at y put 9 life pres]v]s & x floats bett] ?an any?+ ,i "k (4 ,!y'd be bett] ) no?+ 9 !m at all1 said a second4 ,pump all ! air out & leave vacuums4 ,!y're air-tight & !y are /rong en\gh to resi/ ! air pressure4 ,b ! ?ird man said1 ,:y1 y've got to h "s air 9 !m to buoy !m up4 ,cork w\ld be all "r1 b x isn't z light z air2 s air w\ld be ! be/ ?+ to fill !m )4 ,:i* way w\ld ! floats h work$ be/8 ,,application #g4 ,a little girl 0 tell+ h] class ab\t iceb]gs4 ,!y are v dang]\s1 %e said1 & %ips are (t5 wreck$ by runn+ into !m4 ,y see1 ! sun melts ! top (f !m s t all !re is left is "u wat]4 ,! sailors c't see ! ice "u wat]1 & s _! %ips run into x & are sunk4 ,ano!r girl object$ to ?is2 %e said1 ,t c\ldn't be2 ! ice w\ld bob up z fa/ z ! top melt$4 ,no1 x w\ldn't1 said a boy4 ,if t l[] "p wasn't heavi] ?an wat]1 x nev] w\ld h /ay$ "u at all4 ,& if x 0 heavi] at ! beg9n+1 x w\ld /ill be heavi] aft] ! top melt$ (f4 ,:o 0 "r8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #aa4 ,:5 y wa% di%es1 a cup (t5 floats on top ( ! wat]1 :ile a plate made ( ! same sort ( *9a s9ks to ! bottom ( ! pan4 #ab4 ,if y put ! cup 9 sidewise1 x s9ks4 #ac4 ,! wat] 9 ! cup1 :5 ly+ on its side1 is exactly z high z ! wat] 9 ! di% pan4 #ad4 ,if y put a glass into ! wat]1 m\? fir/1 ! wat] _c get up into ! glass2 if y tip x a little1 !re are bubbles 9 ! wat] & "s wat] ent]s ! glass4 #ae4 ,if y let a di% slip :ile y are wip+ x1 x cra%es to ! floor4 #af4 ,x is mu* h>d] to hold a l>ge platt] :ile y are wip+ x ?an x is to hold a small butt] plate4 #ag4 ,if y set a hot glass upside d[n on ! oilclo? table cov]1 ! oilclo? bulges up into x :5 ! hot air & /eam %r9k & leave a p>tial vacuum )9 ! glass4 #ah4 ,if y spill any ( ! di%wat] on ! floor1 x flatt5s out4 #ai4 ,y may use a k9d ( soap t is full ( invisible little air bubbles2 if y d1 ! soap w float on top ( ! wat]4 #bj4 ,:5 y drop a dry di%clo? into wat]1 x floats until all ! pores are fill$ ) wat]2 !n x s9ks4 ,,section #e4 ,h[ ?+s are kept f toppl+ ov]3 ,/ability4 ,:y is x h>d] to keep y\r balance on /ilts ?an on y\r feet8 ,:y does a r[boat tip ov] m easily if y /& up 9 x8 ,9 ,pisa1 ,italy1 !re is a beautiful m>ble bell t[] :i* leans ov] z if x 7 j ab\t to fall to ! gr\nd4 ,yet x has /ood 9 ?is position = hundr$s ( ye>s & has nev] giv5 a sign ( toppl+4 ,! f\ndations on :i* x re/$ sank d[n into ! gr\nd on "o side :ile ! t[] 0 be+ built 7x took ov] #bjj ye>s to build x71 & ?is made x tip4 ,b ! m5 :o 7 build+ x evid5tly felt sure t x w\ld n fall ov] 9 spite ( its tipp+4 ,!y knew ! law ( /ability4 ,illu/ration3 ,,fig4 #ac4 ,! ,lean+ ,t[] ( ,pisa4 ,all ar*itects & eng9e]s & build]s h to take ?is law into consid]ation or ! /ructures !y put up w\ld topple ov]4 ,& y\r body le>n$ ! law :5 y 7 a little ov] a ye> old1 or y nev] c\ld h walk$4 ,x is wor? :ile = y\r bra9 to "k x1 too1 because x is a v practical law t y c use 9 y\r ev]yday life4 ,if y wi% to und]/& :y ! ,lean+ ,t[] ( ,pisa does n fall ov]1 :y x is h>d to walk on /ilts1 :y a boat tips :5 a p]son /&s up 9 x1 :y blocks fall :5 y build too high ) !m1 & h[ to keep ?+s f tipp+ ov]1 d ! foll[+ exp]im5t & read ! explanation t foll[s x3 ,,exp]im5t #ab4b ,unscrew ! bell f a doorbell or a telephone4 ,y w n h>m x at all1 & y c put x back aft] ! exp]im5t4 ,cut a %eet ( heavy wrapp+ pap] or light-weight c>dbo>d ab\t #e #i in*es4 ,roll ?is s z to make a cyl9d] ab\t #e in*es high & z big ar\nd z ! bell4 ,hold x 9 %ape by pa/+ x or putt+ a c\ple ( rubb] b&s ar\nd x4 ,cut two /rips ( pap] ab\t an in* wide & #h in*es long2 lay ^! crosswise2 lay ! bell1 r\nd side d[n1 on ! c5t] ( ! cross4 ,pu% a pap] fa/5] ?r\gh ! hole 9 ! bell 7! k9d %[n 9 ,figure #ad7 & ?r\gh ! cross$ pieces ( pap]1 spread+ ! fa/5] out s z to fa/5 ! pap] cross to ! r\nd$ side ( ! bell4 ,b5d ! arms ( ! cross up ar\nd ! bell & pa/e !m to ! sides ( ! pap] cyl9d] s t ! bell makes a curv$ bottom to ! cyl9d]1 z %[n 9 ,figure #ae4 ,illu/ration3 ,,fig4 #ad4 ,footnote #b3 ,,to ,,! ,,tea*]4 ,if y h a laboratory1 x is well to h ?is cyl9d] already made = ! use ( all classes4 ,illu/ration3 ,,fig4 #ae4 ,9 ?is cyl9d] ! c5t] ( weight is s high t x is n ov] ! bottom if ! cyl9d] is tipp$ to any ext5t4 ,s ! cyl9d] falls ov] easily & lies quietly on its side4 ,illu/ration3 ,,fig4 #af4 ,b 9 ?is "o ! c5t] ( weight is s l[ t x is ov] ! base1 no matt] :at position ! cyl9d] is 94 ,illu/ration3 ,,fig4 #ag4 ,s ev5 if ! cyl9d] is laid on its side x imm$iately comes to an upright position aga94 ,try to tip ! cyl9d] ov]4 ,n[ /uff "s crumpl$ pap] loosely into ! cyl9d]1 fill+ x to ! top4 ,tip ! cyl9d] aga94 ,w x /ay on its side n[8 ,=ce all ! crumpl$ pap] to ! bottom ( ! cyl9d]4 ,n[ w x /ay on its side8 ,take out ! crumpl$ pap] & lay a flat /one 9 ! bottom ( ! bell1 hold+ x 9 place by /uff+ "s crumpl$ pap] 9 on top ( x4 ,w ! cyl9d] tip ov] n[8 ,take ! /one out1 put ! crumpl$ pap] 9 ! bottom ( ! cyl9d]1 put ! /one on top ( ! pap]1 & aga9 try to tip ! cyl9d] ov]4 ,w x fall8 99 99 99 99 99 ,! c5t] ( ! cyl9d] 0 always 9 "o place1 ( c\rse4 ,b ! c5t] ( ! weight 9 t cyl9d] 0 usually ne> ! bottom1 because ! bell weigh$ s mu* m ?an ! pap]4 ,:5 y rais$ ! c5t] ( weight by putt+ ! /one up high or fill+ ! cyl9d] ) crumpl$ pap]1 j a little tipp+ mov$ ! c5t] ( weight s t x 0 n directly ov] ! bell on :i* ! cyl9d] 0 re/+4 ,:5ev] ! c5t] ( weight is n ov] ! base ( support 7! bottom on :i* ! ?+ is /&+71 an object w topple ov]4 ,mov+ ! c5t] ( weight up 7,figs4 #ae & #af7 makes an object less /able4 ,! two ma9 po9ts to rememb] ab\t /ability are ^!3 ! wid] ! base ( an object1 ! h>d] x is to tip ov]2 & ! l[] ! c5t] ( ! weight is1 ! h>d] x is to tip ov]4 ,if y 7 out 9 a r[boat 9 a /orm1 w\ld x be bett] to sit up /raight 9 ! seat or to lie 9 ! bottom ( ! boat8 ,:y is a flat-bottom$ boat saf] ?an a canoe8 ,illu/ration3 ,,fig4 #ah4 ,:i* vase w\ld be ! h>de/ to upset8 ,:]e d y suppose ! c5t] ( weight ( ! ,lean+ ,t[] ( ,pisa is1--ne> ! bottom or ne> ! top8 ,,application #h4 ,if y _h a l>ge fl[] to put into a vase & y did n want x to tip ov] easily1 :i* ( ! ?ree vases %[n 9 ,figure #ah w\ld y *oose8 ,,application #i4 ,"s boys made !mselves a little sail-boat & w5t sail+ 9 x4 ,a /orm came up4 ,! boat rock$ badly & 0 9 dang] ( tipp+ ov]4 ,?r[ out all ! heavy ?+s1 quick6 %\t$ "o4 ,no1 no1 don't = ! life ( y d x6 call$ ano!r4 ,*op d[n ! ma/--"h1 give me ! hat*et6 ano!r "o said4 ,cr\* way d[n--lie on ! bottom4 ,no1 keep mov+ ov] to ! side t is tipp$ up6 ,hold ! ?+s 9 ! bottom ( ! boat /ill1 s !y'll n keep roll+ f side to side4 ,jump out & swim6 ,e "o 0 %\t+ at once4 ,:i* p>ts ( ! advice %\ld y h foll[$ if y _h be5 on bo>d8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #ba4 ,a %ip :5 x goes to sea always c>ries balla/ 7weight7 9 its bottom4 #bb4 ,if ! %ip spr+s a leak bel[ ! wat] l9e1 ! wat] ru%es 94 #bc4 ,! %ip's pumps suck ! wat] up out ( ! bottom ( ! %ip4 #bd4 ,! wat] p\rs back into ! sea f ! m\?s ( ! pumps4 #be4 ,z ! sailors move back & =? on ! %ip dur+ a /orm1 !y walk ) _! legs spread f> ap>t4 #bf4 ,al?\gh ! %ip tips f> f side to side1 x rights itself4 #bg4 ,h[ev] f> ! %ip tips1 ! surface ( ! wat] 9 ! bottom /ays almo/ horizontal4 #bh4 ,:ile ! %ip is 9 dang]1 ! p put on life pres]v]s1 :i* are fill$ ) cork4 #bi4 ,:5 ! %ip rocks viol5tly1 p :o are /&+ up are ?r[n to ! floor1 b ^? :o are sitt+ d[n d n fall ov]4 #cj4 ,if ! %ip fills ) wat] fa/] ?an ! eng9es c pump x out1 ! %ip s9ks4 ,,*apt] ,,two ,,molecul> ,,attraction ,,section #f4 ,h[ liquids are absorb$3 ,capill>y attraction4 ,:y d blott]s pull wat] into !mselves :5 a flat piece ( glass w n8 ,h[ does a t[el dry y\r face8 ,suppose y c\ld turn (f nature's laws 9 ! way t y c turn (f electric lights4 ,& suppose y /ood 9 front ( a swit*bo>d ) ea* swit* label$ ) ! "n ( ! law x w\ld %ut (f4 ,( c\rse1 !re is no su* swit*bo>d1 b we "k pretty well :at w\ld happ5 if we c\ld %ut (f v>i\s laws4 ,"o ( ! lea/ dang]\s-look+ swit*es w\ld be "o label$ ,,capill>y ,,attraction4 ,& n[1 j = fun1 suppose t y h turn$ t swit* (f 9 ord] to see ! effect4 ,at fir/ y d n notice any *ange2 b aft] a :ile y beg9 to feel p]spiration collect+ all ov] y\r body z if y\r clo!s 7 made ( rubb] %eet+4 ,soon ?is becomes s uncom=table t y decide to take a ba?4 ,b :5 y put y\r wa% clo? into ! wat] y f9d t x w n absorb any wat] at all2 x gets a little wet on ! outside1 b rema9s /iff & is n easy or pleasant to use4 ,y rea* = a sponge or a ba? bru%1 b y are no bett] (f4 ,only ! outside ( ! sponge & bru% becomes wet1 & !y rema9 = ! mo/ "p h>% & dry4 ,!n p]haps y try to dry y\rself ) a t[el4 ,b t does n "w2 n a drop ( wat] w ! t[el absorb4 ,y might z well try to dry y\rself on ! glossy side ( a piece ( oilclo?4 ,by ?is "t y are %iv]+2 s y probably decide to light ! oil /ove & get w>m & dry ov] t4 ,b ! oil w n come up ! wick6 ,z a la/ resort y ?r[ a dress+ g[n ar\nd y 7x does n get wet7 & />t a fire 9 ! fireplace4 ,?is at la/ w>ms & dries y2 b z soon z y are dress$ ! clammy feel+ comes aga9--y\r clo!s w n absorb any p]spiration4 ,:ile ! capill>y attraction swit* is turn$ (f y w simply h to get us$ to ?is4 ,!n suppose y />t to write y\r exp]i5ce4 ,y\r f\nta9 p5 w n "w4 ,ev5 an ord9>y p5 does n "w z well z x ought to4 ,x makes a blot on y\r pap]4 ,if y use ! blott] y are dismay$ to f9d t ! blot spreads out z flat z if y 7 press+ a piece ( glass aga9/ x4 ,y take y\r eras] & try to remove ! blot4 ,to y\r delight y f9d t x rubs out z easily z a p5cil m>k4 ,! ink has n soak$ into ! pap] at all4 ,y beg9 to see "s ( ! advantages 9 %utt+ (f capill>y attraction4 ,p]haps y are writ+ at ! d9+-room table1 & y ov]turn ! inkwell on ! tableclo?4 ,nev] m9d1 x is no tr\ble to bru% ! ink (f4 ,n a sign ( /a9 is left beh9d4 ,by & by y look outdoors at ! g>d54 ,ev]y?+ is )]+4 ,! moi/ure does n move ?r\gh ! e>? to :]e ! roots ( ! plants c rea* x4 ,be=e ev]y?+ )]s completely1 y ru% to ! swit*bo>d & turn on ! capill>y attraction aga94 ,y c und]/& ?is =ce ( capill>y attraction bett] if y p]=m ! foll[+ exp]im5ts3 ,,exp]im5t #ac4 ,fill a glass ) wat] & color x ) a little blue+ or r$ ink4 ,into ! glass put two or ?ree glass tubes1 op5 at bo? ends1 & ) bores ( diff]5t sizes4 7,"o ( ^! tubes %\ld be s-call$ !rmomet] tub+1 ) ab\t #a mm4 bore47 ,wat* ! color$ wat] & see 9 :i* ( ! tubes x is pull$ highe/4 ,,exp]im5t #ad4 ,put a clean wa%$ lamp wick into ! glass ( color$ wat] & wat* to see if ! wat] is pull$ up ! wick4 ,n[ let ! upp] end ( ! wick hang ov] ! side ( ! glass all night4 ,put an empty glass "u ! end t is hang+ out4 ,! next morn+ see :at has happ5$4 ,illu/ration3 ,,fig4 #ai4 ,w ! wat] be drawn up high] 9 ! f9e glass tube or 9 a tube ) a l>g] op5+8 ,illu/ration3 ,,fig4 #bj4 ,! wat] rises ?r\gh ! lamp wick by capill>y attraction4 ,! space betwe5 ! ?reads ( ! wick1 & especially ! /ill f9] spaces betwe5 ! fib]s t make up ! ?reads1 act l f9e tubes & ! liquid rises 9 !m j z x did 9 ! f9e glass tube4 ,:]ev] !re are f9e spaces betwe5 ! p>ticles ( any?+1 z !re are 9 a lump ( sug>1 a t[el1 a blott]1 a wick1 & hundr$s ( o!r ?+s1 ^! spaces act l f9e tubes & ! liquid goes into !m4 ,! =ce t causes ! liquid to move along f9e tubes or op5+s is call$ capill>y attraction4 ,capill>y attraction--?is t5d5cy ( liquids to g into f9e tubes--is caus$ by ! same =ce t makes ?+s cl+ to ea* o!r 7adhesion71 & t makes ?+s hold toge!r 7cohesion74 ,! next two sections tell ab\t ^! two =ces2 s y w und]/& ! cause ( capill>y attraction m ?or\ghly aft] read+ !m4 ,b y %\ld "k capill>y attraction :5 y see x n[1 & "k h[ to use x4 ,! foll[+ que/ions w %[ :e!r or n y d3 ,,application #aj4 ,suppose y h spill$ "s milk on a c>pet1 & t y h at h& wet tea leaves1 dry corn meal1 "s torn bits ( a glossy magaz9e cov]1 & a piece ( new clo? ! pores ( :i* are /opp$ up ) />*4 ,:i* w\ld be ! be/ to use 9 tak+ up ! milk8 ,,application #aa4 ,a boy spatt]$ "s c&le grease on 8 coat4 ,8 aunt told him to lay a blott] on ! c&le grease & to press a hot iron on ! blott]1 or to put ! blott] "u 8 coat & ! iron on top ( ! c&le grease1--he 0 n q sure :i*4 ,:ile he 0 try+ to recall 8 aunt's directions1 8 si/] said t he c\ld use soap & wat] to take ! grease out2 !n 8 bro!r told him to scrape ! spot ) a knife4 ,:i* w\ld h be5 ! "r ?+ = him to d8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #ca4 ,a p5 has a slit runn+ d[n to ! po9t4 #cb4 ,:5 a man smokes1 ! smoke goes f ! cig> into 8 m\?4 #cc4 ,a blott] :i* has "o end 9 wat] soon becomes wet all ov]4 #cd4 ,cream comes to ! top ( milk4 #ce4 ,x is mu* h>d] to /& on /ilts ?an on y\r feet4 #cf4 ,oil$ %oes are almo/ wat]pro(4 #cg4 ,city wat] res]voirs are locat$ on ! highe/ possible places 9 or ne> cities4 #ch4 ,y c fill a self-fill+ f\nta9 p5 by squeez+ ! bulb1 !n lett+ g4 #ci4 ,! oceans d n fl[ (f ! _w4 #dj4 ,:5 y turn a bottle ( wat] upside d[n ! wat] gurgles out in/ead ( com+ out 9 a smoo?1 /eady /ream4 ,,section #g4 ,h[ ?+s /ick to "o ano!r3 ,adhesion4 ,:y is x t :5 a ?+ is brok5 x w n /ay toge!r )\t glue8 ,:y does *alk /ay on ! blackbo>d8 ,n[ t y h f\nd out some?+ ab\t capill>y attraction1 suppose t y %\ld g to ! imag9>y swit*bo>d aga9 & tamp] ) "s o!r law ( nature4 ,an innoc5t-look+ swit*1 "r above ! capill>y attraction swit*1 w\ld be label$ ,,adhesion4 ,suppose y h turn$ x (f3 ,9 an in/ant ! wall pap] slips d[n f ! walls & crumples to a heap on ! floor4 ,! pa9t & v>ni% drop f ! woodwork l s mu* s&4 ,e cobweb & speck ( du/ rolls (f & falls 9 a little black heap bel[4 ,:5 y try to wa%1 y _c wet y\r h&s4 ,b !y d n ne$ wa%+1 z ! dirt tumbles (f1 leav+ !m clean] ?an !y ev] 7 be=e4 ,y c jump into a tank ( wat] ) all y\r clo!s on & come out z dry z y w5t 94 ,y discov] by ! dryness ( y\r clo!s t capill>y attraction /opp$ :5 ! adhesion 0 turn$ (f1 = capill>y attraction is j a "p ( adhesion4 ,b y are n tr\bl$ n[ ) ! clamm9ess ( unabsorb$ p]spiration4 ,! p]spiration rolls (f 9 little drops1 n wett+ any?+ b runn+ to ! gr\nd l s mu* quicksilv]4 ,y\r hair is fluffi] ?an aft] ! mo/ vigor\s %ampoo4 ,y\r sk9 sm>ts ) dryness4 ,y\r eyes are almo/ bl9d$ by _! lack ( te>s4 ,ev5 :5 y cry1 ! te>s roll f y\r eyeballs & eyelids l wat] f a duck's back4 ,y\r m\? is too dry to talk2 all ! saliva rolls d[n y\r ?roat1 leav+ y\r tongue & *eeks z dry z corn/>*4 ,i ?9k y w\ld soon turn on ! adhesion swit* aga94 ,,exp]im5t #ae4 ,t\* ! surface ( a glass ( wat]1 & !n raise y\r f+] slightly4 ,notice :e!r ! wat] t5ds to foll[ or to keep away f y\r f+] z y raise x4 ,n[ dip y\r :ole f+] into ! wat] & draw x out4 ,notice h[ ! wat] cl+s1 & wat* ! drops =m & fall (f4 ,notice ! film ( wat] t /ays on1 wett+ y\r f+]1 aft] all dropp+ /ops4 ,illu/ration3 ,,fig4 #ba4 ,z ! f+] is rais$ ! wat] is drawn up aft] x4 ,:i* d y ?9k is ! /rong]1 ! pull ( gravity :i* makes "s ( ! wat] drip (f1 or ! pull ( adhesion :i* makes "s ( ! wat] cl+ to y\r f+]8 ,if ! pull ( gravity is /rong]1 w\ld n all ! wat] drop (f1 leav+ y\r f+] dry8 ,if ! pull ( adhesion is ! /rong]1 w\ld n all ! wat] /ay on y\r f+]1 none dropp+ (f8 ,! tru? ( ! matt] is t gravity is /rong] ?an adhesion unless ?+s are v close toge!r2 !n adhesion is /rong]4 ,! "p ( ! wat] t is v close to y\r f+] cl+s to x 9 spite ( gravity2 ! "p t is f>!r away =ms drops & falls d[n because ( ! pull ( gravity4 ,adhesion1 !n1 is ! =ce t makes ?+s cl+ to ea* o!r :5 !y are v close toge!r4 ,,:y ,,x ,,is ,,easi] ,,to ,,turn ,a ,,page ,,if ,,y ,,wet ,,y\r ,,f+]4 ,wat] spreads out on ?+s s t x gets v close to !m4 ,! ?9 film ( wat] on y\r f+] is close en\gh to y\r f+] & to ! page :i* y are turn+ to cl+ to bo?2 s :5 y move y\r f+]1 ! page moves along ) x4 ,,:y ,,du/ ,,cl+s ,,to ,,! ,,ceil+ ,,& ,,walls4 ,! f9e p>ticles ( du/ are waft$ up aga9/ ! ceil+ & walls by ! mov+ air 9 ! room4 ,!y are s small t !y c fit into ! small d5ts t are 9 pla/] & pap] & c get v close to ! wall4 ,once !y get close en\gh1 ! =ce ( adhesion holds !m ) a pull /rong] ?an t ( gravity4 ,oily & wet surfaces cat* du/ mu* m readily ?an clean1 dry ones1 simply because ! du/ c get s mu* clos] to ! oil or wat] film & because ?is film fl[s p>tly ar\nd ea* du/ p>ticle & holds x by ! =ce ( adhesion4 ,?is is :y y\r face gets mu* dirti] :5 x is p]spir+ ?an :5 x is dry4 ,,application #ab4 ,expla9 :y cobwebs d n fall f ! ceil+2 :y du/ cl+s to a wet broom2 :y a po/age /amp does n fall (f an envelope4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #da4 ,!re are no spr+s on ! tops ( high m\nta9s4 #db4 ,p us$ to %ake s& ov] _! lett]s aft] writ+ !m 9 ink4 #dc4 ,p us$ to make night lights = b$rooms by p\r+ "s oil into a cup ( wat] & float+ a piece ( wick on ! oil4 ,! oil always /ay$ on top ( ! wat]1 & w5t up ?r\gh ! wick fa/ en\gh to keep ! light burn+4 #dd4 ,y\r face becomes mu* dirti] :5 y are p]spir+4 #de4 ,ink bottles are usually made ) wide bases4 #df4 ,:5 y spill wat] on ! floor1 y _c wipe x up ) wrapp+ pap]1 b y c dry x easily ) a clo?4 #dg4 ,oil$ mops are us$ 9 tak+ up du/4 #dh4 ,cake w /ick to a pan unless ! pan is greas$4 #di4 ,al?\gh ! e>? turns completely ov] e day1 we nev] fall (f x4 #ej4 ,signs are fa/5$ sometimes to w9d[s or to ! w9d %ields ( automobiles by little rubb] suction caps4 ,,section #h4 ,! =ce t makes a ?+ hold toge!r3 ,cohesion4 ,:at makes ra9 fall 9 drops8 ,:y are diamonds h>d8 ,y h n yet t\*$ any ( ! mo/ dang]\s swit*es on ! imag9>y swit*bo>d ( univ]sal laws4 ,b if y\r exp]i5ce 9 turn+ (f ! capill>y attraction & adhesion swit*es did n disc\rage y1 y might try turn+ (f ! "o beside !m label$ ,,cohesion3 ,illu/ration3 ,,fig4 #bb4 ,el ,capitan1 ,yosemite ,valley1 ,cali=nia4 ,if ! =ce ( cohesion 7 susp5d$1 a m\nta9 l ?is w\ld imm$iately become ! f9e/ du/4 ,?+s happ5 too swiftly = y to "k mu* ab\t !m4 ,! h\se y are 9 falls to du/ in/antly4 ,y fall ?r\gh ! place :]e ! floor has be52 b y d n bump on ! cem5t basem5t floor bel[1 p>tly because !re is no su* ?+ z a h>d floor or ev5 h>d gr\nd any:]e1 & p>tly because y dis9tegrate--fall to pieces--s completely t !re is no?+ left ( y b a grayi% film ( f9e du/ & a haze ( w>m wat]4 ,) a deaf5+ ro>1 rocks1 skyscrap]s1 & ev5 m\nta9s tumble d[n1 fall to pieces1 & s9k into an inconceivably f9e du/4 ,no?+ /&s up 9 ! _w--n a tree1 n an animal1 n an isl&4 ,) a wild ru% ! oceans flood 9 ov] ! du/ t has be5 nations & cont95ts1 & !n ?is du/ turns to a f9e muddy ooze 9 ! bottom ( a worldwide sea4 ,b x is an ocean utt]ly diff]5t f :at we h 9 ! real _w4 ,!re are no waves4 ,nei!r are !re any reflections ( cl\ds 9 its surface1--fir/ because ! cl\ds w\ld fly to pieces & turn to invisible vapor1 & second1 because ! ocean has no surface--x simply melts away into ! air & no "o c tell :]e ! wat] /ops & :]e ! air beg9s4 ,!n ! e>? gr[s l>g] & l>g]4 ,! ocean turns to a heavy1 d5se1 transp>5t /eam4 ,! f9e mud t us$ to be rocks & m\nta9s & liv+ ?+s turns to a heavy1 d5se gas4 ,our once beautiful1 solid1 w>m1 liv+ e>? n[ :irls on ?r\gh space1 a swoll51 gase\s globe1 utt]ly dead4 ,& ! only ?+ t prev5ts all ?is f actually happ5+ "r n[ is t !re is a =ce call$ cohesion t holds ?+s toge!r4 ,x is ! pull :i* "o p>ticle ( any?+ has on ano!r p>ticle ( ! same mat]ial4 ,! pap] 9 ?is book1 ! *air on :i* y are sitt+1 & y y\rself are all made ( a va/ numb] ( un?9kably small p>ticles call$ molecules1 ea* ( :i* is pull+ on its neighbor ) su* =ce t all /ay 9 _! places4 ,sub/ances 9 :i* !y pull ! h>de/1 l /eel1 are v h>d to break 9 two2 t is1 x is difficult to pull ! molecules ( ^! sub/ances ap>t4 ,9 liquids1 su* z wat]1 ! molecules d n pull ne>ly s h>d on ea* o!r4 ,9 a gas1 su* z air1 !y are s f> ap>t t !y h practically no pull on ea* o!r at all4 ,t is :y ev]y?+ w\ld turn to a gas if ! =ce ( cohesion /opp$4 ,:y ?+s w\ld turn cold w be expla9$ 9 ,*apt] #d4 ,cohesion1 adhesion1 & capill>y attraction1 all are ! result ( ! pull ( molecules on ea* o!r4 ,! diff]5ce is t capill>y attraction is ! pull+ ( p>ticles ( liquids up into f9e spaces1 z :5 a lamp wick draws up oil2 adhesion is ! pull ( ! p>ticles ( "o sub/ance or ?+ on ! p>ticles ( ano!r :5 !y are v close toge!r1 z :5 wat] cl+s to y\r h& or :5 du/ /icks to ! ceil+2 :ile cohesion is ! cl++ toge!r ( ! p>ticles ( ! same sub/ance1 l ! hold+ toge!r ( ! p>ticles ( y\r *air or ( ?is pap]4 ,:5 y put y\r h& into wat] x gets wet because ! adhesion ( ! wat] to y\r h& is /rong] ?an ! cohesion ( ! wat] itself4 ,! p>ticles ( ! wat] are drawn to y\r h& m p[]fully ?an !y are drawn to ea* o!r4 ,b 9 ! foll[+ exp]im5t1 y h an example ( cases :]e cohesion is /rong] ?an adhesion3 ,,exp]im5t #af4 ,p\r "s m]cury 7quicksilv]7 into a small di% & dip y\r f+] into x4 ,z y raise y\r f+]1 see if ! m]cury foll[s x up z ! wat] did 9 ,exp]im5t #ad4 ,:5 y pull y\r f+] all ! way out1 has ! m]cury wet x at all8 ,put a lamp wick or a "p ( y\r h&k]*ief into ! m]cury4 ,does x draw ! m]cury up z x w\ld draw up wat]8 ,illu/ration3 ,,fig4 #bc4 ,! m]cury does n wet ! f+]1 & z ! f+] is lift$ ! m]cury does n foll[ x4 ,! reason = ?is peculi>ity ( m]cury is t ! pull betwe5 ! p>ticles ( m]cury !mselves is /rong] ?an ! pull betwe5 !m & y\r f+] or h&k]*ief4 ,9 sci5tific language1 ! cohesion ( ! m]cury is /rong] ?an its adhesion to y\r f+] or h&k]*ief4 ,al?\gh ?is seems unusual = a liquid1 x is :at we naturally expect ( solid ?+s2 y w\ld be amaz$ if "p ( ! wood ( y\r s*ool seat /uck to y :5 y got up1 = y expect ! p>ticles 9 solid ?+s to coh]e--to h cohesion--mu* m /rongly ?an !y adh]e to some?+ else4 ,x is because solids h su* /rong cohesion t !y are solids4 ,,application #ac4 ,expla9 :y m]cury _c wet y\r f+]s2 :y ra9 falls 9 drops2 :y x is h>d] to drive a nail into wood ?an into soap2 :y /eel is h>d4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #ea4 ,ink spill$ on a pla9 bo>d soaks 91 b on a v>ni%$ desk x c be easily wip$ (f4 #eb4 ,:5 a w9d[ is soil$ y c write on x ) y\r f+]2 !n y\r f+] becomes soil$4 #ec4 ,a />*$ apron or %irt /ays clean long] ?an an un/>*$ "o4 #ed4 ,:5 y hold a lump ( sug> ) "o edge j t\*+ ! surface ( a cup ( c(fee1 ! c(fee runs up ! lump4 #ee4 ,a drop ( wat] on a dry plate is n flat b r\nd$4 #ef4 ,x is h>d to write on clo? because ! ink spreads out & blurs4 #eg4 ,if y r\gh5 y\r f+] nails by clean+ !m ) a knife1 !y w get soil$ mu* m quickly ?an if y keep !m smoo? by us+ an orange /ick4 #eh4 ,:5 y dip y\r p5 9 ! ink & !n move x across ! pap]1 x makes ink m>ks on ! pap]4 #ei4 ,if y suck ! air out ( a bottle1 ! bottle w /ick to y\r tongue4 #fj4 ,y _c break a ?ick piece ( iron ) y\r h&s4 ,,section #i4 ,friction4 ,:at makes ice slipp]y8 ,h[ does a brake /op a c>8 ,:y d ?+s we> out8 ,x w\ld n be su* a calamity if we 7 to turn (f friction f ! _w4 ,/ill1 ,i d\bt :e!r we %\ld want to leave x (f mu* long] ?an 0 necess>y = u to see :at w\ld happ54 ,suppose we imag9e ! _w ) all friction remov$3 ,a man on a bicycle c coa/ =ev] along level gr\nd4 ,%ips at sea c %ut (f /eam & coa/ cle> across ! ocean4 ,no ma*9]y ne$s oil+4 ,! clo!s on y\r body feel smoo!r & s(t] ?an ! f9e/ silk4 ,p]petual motion is an e/abli%$ fact in/ead ( an absolute impossibility2 ev]y?+ t is n go+ aga9/ gravity w keep "r on mov+ =ev] or until x bumps into some?+ else4 ,b1 if !re is no friction & y want to /op1 y _c4 ,suppose y are 9 an automobile :5 all friction /ops4 ,y spe$ along helplessly 9 ! direction y are go+4 ,y _c /e] ! ma*9e--y\r h&s w\ld slip "r ar\nd on ! /e]+ :eel1 & ev5 if y turn x by grasp+ ! spoke1 y\r ma*9e /ill skids /raight =w>d4 ,if y />t to g up a hill1 y sl[ d[n1 /op1 & !n be=e y c get out ( ! ma*9e y />t backw>d d[n ! hill aga9 & keep on go+ backw>d until y sma% into some?+4 ,a p]son on foot does n f>e mu* bett]4 ,if he is walk+ at ! "t friction ceases1 ! gr\nd is sudd5ly s slipp]y t he falls d[n & slides along on 8 back or /oma* 9 ! same direction he 0 walk+1 until he bumps into some?+ big or />ts to slip up a slope4 ,if he rea*es a slope1 he1 l ! automobile1 /ops an in/ant a little way up1 !n />ts slid+ helplessly backw>d4 ,ano!r man is /&+ /ill :5 ! friction is turn$ (f4 ,he _c get any:]e4 ,z soon z he />ts to walk =w>d1 8 feet slip out f "u him & he falls on 8 face4 ,he lies 9 ! same spot no matt] h[ he wriggles & squirms4 ,if he tries to pu% ) 8 h&s1 !y slip ov] ! r\gh gr\nd m easily ?an !y n[ slip ?r\gh air4 ,he _c pu% sideways en\gh ev5 to turn ov]4 ,if !re happ5s to be a rope )9 rea* & "o end is ti$ to a tree1 he might try to take hold ( ! rope to pull himself along4 ,b no matt] h[ tightly he squeezes1 ! rope slips "r ?r\gh 8 h&s :5 he />ts to pull4 ,if1 h[ev]1 !re is a loop 9 ! rope1 he c slip 8 h& ?r\gh ! loop & try to pull4 ,b ! knots ) :i* ! rope is ti$ imm$iately come unti$ & he is z helpless z ev]4 ,ev5 if he takes hold ( a bo>d f5ce he is no m successful4 ,! nails 9 ! bo>d slip out ( _! holes & he is left ) a p]fectly slipp]y & useless bo>d on ! gr\nd beside him = a companion4 ,z x gr[s cold t[>d ev5+ he may take "s mat*es out ( 8 pocket & try to />t a fire4 ,aside f ! difficulty ( 8 be+ unable to hold !m except by ! mo/ c>eful balanc+ or by %utt+ !m up )9 8 slipp]y h&s1 he is entirely incapable ( light+ !m2 !y slip ov] ! cem5t b5ea? him or ov] ! sole ( 8 %oe )\t ! lea/ rubb+4 ,9 ! real _w1 h[ev]1 x is =tunately z impossible to get away f friction z x is to get away f ! o!r laws we h tri$ to imag9e z be+ turn$ (f4 ,!re is always "s friction1 or rubb+1 :5ev] any?+ moves4 ,a bird rubs aga9/ ! air1 ! po9t ( a sp9n+ top rubs aga9/ ! sidewalk on :i* x is sp9n+4 ,y\r %oes rub aga9/ ! gr\nd z y walk & s make x possible = y to pu% y\rself =w>d4 ,! drive :eels ( ma*9]y rub aga9/ ! belts & pull !m along4 ,!re is friction betwe5 ! :eels ( a c> & ! track !y are pu%+ aga9/1 or ! :eels w\ld :irl ar\nd & ar\nd uselessly4 ,illu/ration3 ,,fig4 #bd4 ,hockey is a fa/ game because !re is little friction betwe5 ! skates & ! ice4 ,b we c increase or decrease friction a great deal4 ,if we make ?+s r\gh1 !re is m friction betwe5 !m ?an if !y are smoo?4 ,if we press ?+s tightly toge!r1 !re is m friction ?an if !y t\* lightly4 ,a nail 9 a loose hole comes out easily1 b 9 a tight hole x /icks2 ! pressure has increas$ ! friction4 ,a motorman 9 />t+ a trolley c> sometimes f9ds ! track s smoo? t ! :eels :irl ar\nd )\t pu%+ ! c> =w>d2 he p\rs "s s& on ! track to make x r\gh]1 & ! c> />ts4 ,:5 y put on new %oes1 !y are s smoo? on ! bottom t !y slip ov] ! gr\nd because ( ! lack ( friction4 ,if y scrat* ! soles1 !y are r\gh] & y no long] slip4 ,if y try to pull a /ake out ( ! gr\nd1 y h to squeeze x h>d] ?an ! gr\nd does or x w slip out ( y\r h&s in/ead ( slipp+ out ( ! gr\nd4 ,:5 y apply a brake to an automobile1 ! brake mu/ press tightly aga9/ ! axle or :eel to cause en\gh friction to /op ! automobile4 ,!re are always two results ( friction3 heat & we>4 ,sometimes ^! effects ( friction are helpful to u1 & sometimes !y are q ! opposite4 ,! heat f friction is helpful :5 x makes x possible = u to light a fire1 b x is f> f helpful :5 x causes a hot box because ( an ungreas$ :eel on a tra9 or wagon1 or burns y\r h&s :5 y slide d[n a rope4 ,! we> f friction is helpful :5 x makes x possible to s&pap] a table1 sc\r a pan1 scrub a floor1 or erase a p5cil m>k2 b we don't l x :5 x we>s out automobile tires1 all ! p>ts ( ma*9]y1 & our clo!s4 ,,exp]im5t #ag4 ,hold a nail aga9/ a gr9d/one :ile y turn ! /one4 ,notice bo? ! we> & heat4 ,let ! nail re/ lightly on ! /one "p ( ! "t & press h>d "p ( ! "t4 ,:i* way does ! nail get hott]8 ,:i* way does x we> (f m quickly8 ,run x ov] a pane ( glass & see if x gets z hot z x does on ! gr9d/one2 if x we>s d[n z quickly4 ,,:y ,,we ,,oil ,,ma*9]y4 ,we c decrease friction by keep+ objects f press+ tightly aga9/ ea* o!r1 & by mak+ _! surfaces smoo?4 ,! mo/ common way ( mak+ surfaces smoo? is by oil+ or greas+ !m4 ,a film ( oil or grease makes ?+s s smoo? & slipp]y t !re is v little friction4 ,t is :y all k9ds ( ma*9]y w run s smoo?ly if !y are kept oil$4 ,& s9ce ! oil decreases friction1 x decreases ! we> caus$ by friction4 ,s well-oil$ ma*9es la/ mu* long] ?an ma*9es t are n suffici5tly oil$4 ,illu/ration3 ,,fig4 #be4 ,! friction ( ! /one heats ! nail & we>s x away4 ,,:y ,,ball ,,be>+s ,,are ,,us$4 ,!re is mu* less friction :5 a r\nd object rolls ov] a surface ?an :5 two surfaces slide ov] "o ano!r1 unless ! slid+ surfaces are v smoo?2 ?9k h[ mu* easi] x is to pull a wagon =w>d ?an x w\ld be to take hold ( ! :eels & pull ! wagon sidewise4 ,s :5 y want ! lea/ possible friction 9 a ma*9e y use ball be>+s4 ,! be>+s are locat$ 9 ! hub ( a :eel4 ,!n1 in/ead ( ! axle rubb+ aga9/ ! hub1 ! be>+s roll inside ( ! hub4 ,?is causes v little friction2 & ! friction is made /ill less by keep+ ! be>+s oil$4 ,,application #ad4 ,suppose y 7 mak+ a bicycle1--9 :i* ( ! foll[+ places w\ld y want to increase ! friction1 & 9 :i* w\ld y want to decrease x8 ,h&le grips1 axles1 p$als1 tires1 p$al cranks1 ! sockets 9 :i* ! h&le b> turns1 ! nuts t hold ! p>ts toge!r4 ,,application #ae4 ,a small boy decid$ to surprise 8 "m by oil+ h] sew+-ma*9e4 ,he put oil 9 ! foll[+ places3 ,on ! treadle1 on ! l>ge :eel ov] :i* ! belt runs1 on ! axle ( ! same :eel1 on ! groove 9 ! little :eel up above :]e ! belt runs1 on ! jo9t :]e ! ne$le runs up & d[n1 on ! little r\gh place "u ! ne$le t pu%es ! clo? =w>d4 ,:i* ( ^! did he d well to oil & :i* %\ld he h let alone8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #fa4 ,riv]s fl[ nor? z well z s\?1 al?\gh we usually speak ( nor? z up nor?4 #fb4 ,t>t> & bits ( food /ick to y\r tee?4 #fc4 ,bru%+ y\r tee? ) too? p[d] cleans !m4 #fd4 ,:5 a *air has glid]s 7smoo? metal caps7 on its feet1 x slides easily across ! floor4 #fe4 ,:5 y wet y\r f+]1 y c turn a page m easily4 #ff4 ,a lamp wick draws oil up f ! l[] "p ( a lamp to ! burn]4 #fg4 ,! sidewalks on /eep hills are made ( r\gh cem5t4 #fh4 ,c]ta9 fi% c rise 9 ! wat] by exp&+ _! air bladd]s1 al?\gh ?is does n make !m weigh any less4 #fi4 ,:5 y\r h&s are cold1 y rub !m toge!r to w>m !m4 #gj4 ,x is dang]\s to /& up 9 a r[boat or canoe4 ,,*apt] ,,?ree ,,cons]vation ,,( ,,en]gy ,,section #aj4 ,lev]s4 ,h[ a big weight c be lift$ ) a little =ce2 h[ "o ?+ mov+ sl[ly a %ort di/ance c make ano!r move swiftly a long di/ance4 ,:y c y g s mu* fa/] on a bicycle ?an on foot8 ,h[ c a man lift up a heavy automobile by us+ a jack8 ,:y c y crack a h>d nut ) a nutcrack] :5 y _c crack x by squeez+ x betwe5 two pieces ( iron8 ,give me a lev]1 long en\gh & /rong en\gh1 & some?+ to re/ x on1 & ,i c lift ! :ole _w1 said an old ,greek philosoph]4 ,& z a philosoph] he 0 "r2 !oretically x w\ld be possible4 ,b s9ce he ne$$ a lev] t w\ld h be5 z long z f "h to ! f>!/ /> ^: di/ance has ev] be5 measur$1 & s9ce he w\ld h _h to pu% 8 end ( ! lev] some?+ l a qu9tillion 7#a1jjj1jjj1jjj1jjj1jjj1jjj7 miles to lift ! e>? "o in*1 8 proposition 0 h>dly a practical "o4 ,b lev]s are practical4 ,)\t !m !re w\ld be none ( our mod]n ma*9es4 ,no locomotives c\ld spe$ across ! cont95ts2 no d]ricks c\ld lift great weights2 no automobiles or bicycles w\ld quick5 our travel2 our v bodies w\ld be completely p>alyz$4 ,yet ! law back ( all ^! ?+s is really simple4 ,y h (t5 notic$ on ! see-saw t a small *ild at "o end c be balanc$ by a l>g] *ild at ! o!r end1 provid$ t ! l>g] *ild sits ne>] ! middle4 ,:y %\ld x matt] :]e ! l>g] *ild sits8 ,he is always heavi]--:y doesn't he ov]balance ! small *ild8 ,x is because :5 ! small *ild moves up & d[n he goes a long] di/ance ?an ! l>ge *ild does4 ,9 ,figure #bf ! l>ge boy moves up & d[n only half z f> z ! little girl does4 ,%e weighs only half z mu* z he1 yet %e balances him4 ,illu/ration3 ,,fig4 #bf4 ,! little girl raises ! big boy1 b 9 do+ x %e moves twice z f> z he does4 ,y w beg9 to get a g5]al und]/&+ ( lev]s & h[ !y "w by do+ ! foll[+ exp]im5t3 ,,exp]im5t #ah4 ,= ?is exp]im5t !re w be ne$$ a small pail fill$ ) some?+ heavy 7s& or /ones w d71 a y>d/ick ) a hole ?r\gh ! middle & ano!r hole ne> "o end & ) not*es cut "h & !re along ! edge1 & a po/ or table corn] ) a heavy nail driv5 into x to )9 an in* ( ! head4 ,! holes 9 ! y>d/ick mu/ be l>ge en\gh to let ! head ( ?is nail ?r\gh4 ,put ! middle hole ( ! y>d/ick ov] ! nail1 z is %[n 9 ,figure #bg4 ,! nail is ! fulcrum ( y\r lev]4 ,n[ hang ! pail on "o ( ! not*es ab\t halfway betwe5 ! fulcrum & ! end ( ! /ick & put y\r h& on ! opposite side ( ! y>d/ick at ab\t ! same di/ance z ! pail is f ! fulcrum4 ,raise & l[] ! pail sev]al times by mov+ ! opposite end ( ! lev] up & d[n4 ,see h[ mu* =ce x takes to move ! pail4 ,n[ slide y\r h& t[>d ! fulcrum & l[] & raise ! pail f t position4 ,is x h>d] or easi] to lift ! pail f "h ?an f ! fir/ position8 ,:i* moves f>!r up & d[n1 y\r h& or ! pail8 ,next1 slide y\r h& all ! way out to ! end ( ! y>d/ick & raise & l[] ! pail f !re4 ,is ! pail h>d] or easi] to lift8 ,does ! pail move a long] or a %ort] di/ance up & d[n ?an y\r h&8 ,if y want$ to move ! pail a long way )\t mov+ y\r h& z f>1 w\ld y put y\r h& ne>] to ! fulcrum or f>!r f x ?an ! pail is8 ,illu/ration3 ,,fig4 #bg4 ,! y>d/ick is a lev] by :i* he lifts ! pail4 ,illu/ration3 ,,fig4 #bh4 ,a lev] ) ! weight betwe5 ! fulcrum & ! =ce4 ,suppose y want$ to lift ! pail ) ! lea/ possible ef=t1 :]e w\ld y put y\r h&8 ,notice ano!r fact3 :5 y\r h& is at ! end ( ! y>d/ick1 x takes ! same l5g? ( "t to move a long way z ! pail takes to move a %ort way4 ,!n :i* is mov+ fa/]1 y\r h& or ! pail8 ,,exp]im5t #ai4 ,put ! end hole ( ! y>d/ick on ! nail1 z %[n 9 ,figure #bh4 ,! nail is /ill ! fulcrum ( y\r lev]4 ,put ! pail ab\t halfway betwe5 ! fulcrum & ! o!r end ( ! /ick1 & hold ! end ( ! /ick 9 y\r h&s4 ,raise & l[] y\r h& to see h[ h>d or h[ easy x is to lift ! pail f ?is position4 ,:i* is mov+ f>!r1 y\r h& or ! pail8 ,:i* is mov+ fa/]8 ,n[ put y\r h& ab\t halfway betwe5 ! fulcrum & ! pail & raise & l[] x4 ,is x h>d] or easi] to raise ?an be=e8 ,:i* moves f>!r ?is "t1 y\r h& or ! pail8 ,:i* moves fa/]8 ,if y want$ to make ! pail move f>!r & fa/] ?an y\r h&1 w\ld y put y\r h& ne>] to ! fulcrum ?an ! pail is1 or f>!r f ! fulcrum ?an ! pail8 ,if y want$ to move ! pail ) ! lea/ ef=t1 :]e w\ld y put y\r h&8 ,,exp]im5t #bj4 ,use a pair ( long-blad$ %e>s & fold a piece ( c>dbo>d once to lie a/ride y\r own or "s "o else's f+]4 ,put ! f+]1 protect$ by ! c>dbo>d1 betwe5 ! two po9ts ( ! %e>s4 ,!n squeeze ! h&les ( ! %e>s toge!r4 ,see if y c br+ ! h&les toge!r h>d en\gh to hurt ! f+] betwe5 ! po9ts4 ,n[ wat* ! %e>s z y op5 & close ! blades4 ,:i* move f>!r1 ! po9ts ( ! %e>s or ! h&les8 ,:i* move fa/]8 ,next1 put ! f+]1 /ill protect$ by ! c>dbo>d1 betwe5 ! h&les ( ! %e>s & press ! po9ts toge!r4 ,c y p9* ! f+] ?is way h>d] or less h>d ?an 9 ! way y fir/ tri$8 ,d ! po9ts or h&les move f>!r z y close ! %e>s8 ,:i* "p closes ) ! great] =ce8 ,illu/ration3 ,,fig4 #bi4 ,y _c p9* h>d en\gh ?is way to hurt4 ,illu/ration3 ,,fig4 #cj4 ,b ?is is q diff]5t4 ,,exp]im5t #ba4 ,use a ,dov] egg beat]4 ,fa/5 a small piece ( /r+ to "o ( ! blades1 s t y c tell h[ _m times x goes ar\nd4 ,turn ! h&le ( ! beat] ar\nd once sl[ly & c\nt h[ _m times ! blade goes ar\nd4 ,:i* moves fa/]1 ! h&le or ! blade8 ,:]e w\ld y expect to f9d m =ce1 9 ! cogs or 9 ! blades8 ,te/ y\r conclusion ?is way3 ,put y\r f+] betwe5 ! blades & try to p9* x by turn+ ! h&le2 !n place y\r f+] s t ! sk9 is caught betwe5 ! cogs & try to p9* ! f+] by turn+ ! blades4 ,:]e is !re m =ce8 ,:]e is !re m motion8 ,,exp]im5t #bb4 ,put a spool ov] ! nail :i* 0 y\r fulcrum 9 ! fir/ two exp]im5ts4 7,take ! /ick (f ! nail fir/1 ( c\rse47 ,use ?is spool z a pulley4 ,put a /r+ ov] x & fa/5 "o end ( y\r /r+ to ! pail 7,fig4 #cb74 ,lift ! pail by pull+ d[n on ! o!r end ( ! /r+4 ,notice t x is n h>d] or easi] to move ! pail :5 x is ne> ! nail ?an :5 x is ne> ! floor4 ,:5 y\r h& moves d[n f ! nail to ! floor1 h[ f> up does ! pail move8 ,does ! pail move a great] or less di/ance ?an y\r h&1 or does x move ! same di/ance8 ,next fa/5 "o end ( ! /r+ to ! nail4 ,set ! pail on ! floor4 ,pass ! /r+ ?r\gh ! h&le ( ! pail & up ov] ! spool 7,fig4 #cc74 ,pull d[n on ! loose end ( ! /r+4 ,is ! pail easi] to lift 9 ?is way or 9 ! way y fir/ tri$8 ,z y pull d[n ) y\r h&1 notice :e!r y\r h& moves f>!r ?an ! pail1 n s f> z ! pail1 or ! same di/ance4 ,is ! great] am\nt ( motion 9 y\r h& or 9 ! pail8 ,!n :]e w\ld y expect ! great] am\nt ( =ce8 ,illu/ration3 ,,fig4 #ca4 ,:5 ! h&le is turn$ ! blades ( ! egg beat] move mu* m rapidly ?an ! h&4 ,w !y p9* h>d en\gh to hurt8 ,! :ole idea ( ! lev] c be summ$ up l ?is3 "o end ( ! contrivance moves m ?an ! o!r4 ,b en]gy _c be lo/2 s to make up = ?is extra motion at "o end m =ce is always ex]t$ at ! o!r4 ,?is rule is true = all k9ds ( lev]s1 blocks & tackles or pulley sy/ems1 automobile & bicycle ge>s1 belt sy/ems1 cog sy/ems1 d]ricks1 cr[b>s1 & e k9d ( ma*9e4 ,9 mo/ ma*9es y ei!r put 9 m =ce ?an y get out & ga9 motion1 or y put 9 m motion ?an y get out & ga9 =ce4 ,9 ! foll[+ examples ( ! lev] see if y c tell :e!r y are apply+ m =ce & obta9+ m motion1 or :e!r y are putt+ 9 m motion & obta9+ m =ce3 ,crack+ nuts ) a nut crack]4 ,beat+ eggs ) a ,dov] egg beat]4 ,go+ up a hill 9 an automobile on l[ ge>4 ,spe$+ on high ge>4 ,cutt+ clo? ) ! po9ts ( %e>s4 ,cutt+ ne> ! angle ( ! %e>s4 ,turn+ a door knob4 ,pick+ up sug> ) sug> tongs4 ,p9*+ y\r f+] 9 ! crack ( a door on ! h+e side4 ,illu/ration3 ,,fig4 #cb4 ,8 h& goes d[n z f> z ! pail goes up4 ,,application #af4 ,suppose y want$ to lift a heavy fry+ pan (f ! /ove4 ,y h a clo? to keep x f burn+ y\r h&4 ,w\ld x be easi] to lift x by ! end ( ! h&le or by ! "p ( ! h&le ne>e/ ! pan8 ,,application #ag4 ,a boy 0 go+ to :eel 8 little si/] 9 a :eelb>r[4 ,%e want$ to sit 9 ! middle ( ! :eelb>r[2 h] bro!r ?\ght %e %\ld sit z ne> ! h&les z possible s t %e w\ld be ne>] 8 h&s4 ,ano!r boy ?\ght %e %\ld sit z ne> ! :eel z possible4 ,:o 0 "r8 ,,application #ah4 ,james ,mc,dougal liv$ 9 a hilly place4 ,he 0 go+ to buy a bicycle4 ,i want "o t w take ! hills easily1 he said4 ,! deal] %[$ him two bicycles4 ,on "o ! back :eel w5t ar\nd ?ree times :ile ! p$als w5t ar\nd once2 on ! o!r ! back :eel w5t ar\nd f\r & a half times :ile ! p$als w5t ar\nd once4 ,:i* bicycle %\ld ,james h *os58 ,if he _h want$ ! bicycle = rac+1 :i* %\ld he h *os58 ,,application #ai4 ,a wagon /uck 9 ! mud4 ,! driv] got out & tri$ to help ! horse by grasp+ ! spokes & turn+ ! :eel4 ,%\ld he h grasp$ ! spokes ne> ! hub1 ne> ! rim1 or 9 ! middle8 ,illu/ration3 ,,fig4 #cc4 ,) ?is arrangem5t ! pail travels m sl[ly ?an ! h&4 ,w x seem heavi] or light] ?an ) ! arrangem5t %[n 9 ,figure #cb8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #ga4 ,:5 y turn on ! faucet ( a di/ill$-wat] bottle1 bubbles g up ?r\gh ! wat] z ! wat] p\rs out4 #gb4 ,a clo!s wr+] has a long h&le4 ,x wr+s ! clo!s dri] ?an y c wr+ !m by h&4 #gc4 ,y use a cr[b> :5 y want to raise a heavy object su* z a rock4 #gd4 ,sometimes x is almo/ impossible to get ! top f a j> ( cann$ fruit unless y let a little air "u ! edge ( ! lid4 #ge4 ,x is mu* easi] to c>ry a c>pet sweep] if y take hold ne> ! sweep] "p ?an x is if y take hold at ! end ( ! h&le4 #gf4 ,y c make m>ks on a pap] by rubb+ a p5cil across x4 #gg4 ,a motorman s&s ! track :5 he wi%es to /op ! c> on a hill4 #gh4 ,on a faucet !re is a h&le ) :i* to turn x4 #gi4 ,be=e we pull c&y we butt] our f+]s4 #hj4 ,y c scrat* glass ) v h>d /eel b n ) wood4 ,,section #aa4 ,in]tia4 ,:y is x t if y pu% a m9iature auto rapidly1 x w g /raight8 ,:y does ! e>? nev] /op mov+8 ,:5 y j]k a piece ( pap] f "u an inkwell1 :y does ! inkwell /ay /ill8 ,:5 y are rid+ 9 a c> & ! c> /ops sudd5ly1 y are ?r[n =w>d2 y\r body t5ds to keep mov+ 9 ! direction 9 :i* ! c> 0 go+4 ,:5 a c> />ts sudd5ly1 y are ?r[n backw>d2 y\r body t5ds to /ay :]e x 0 be=e ! c> />t$4 ,:5 an automobile bumps into any?+1 ! p 9 ! front seat are (t5 ?r[n =w>d ?r\gh ! w9d %ield & are badly cut2 _! bodies keep on go+ 9 ! direction 9 :i* ! automobile 0 go+4 ,:5 y jump (f a mov+ /reet c>1 y h to run along 9 ! direction ! c> 0 go+ or y fall d[n2 y\r body tries to keep go+ 9 ! same direction x 0 mov+1 & if y\r feet d n keep up1 y topple =w>d4 ,g5]ally we ?9k t x takes =ce to />t ?+s to move1 b t !y w /op ( _! own accord4 ,?is is n true4 ,x takes j z mu* =ce to /op a ?+ z x does to />t x1 & :at usually does ! /opp+ is friction4 ,:5 y %oot a /one 9 a sl+ %ot1 ! contract+ rubb] pulls ! /one =w>d v rapidly4 ,! /one has be5 />t$ & x w\ld g on & nev] /op if no?+ int]f]$ ) x4 ,= in/ance1 if y %\ld g away (f 9 space--say halfway betwe5 "h & a />--& %oot a /one f a sl+ %ot1 t /one w\ld keep on go+ z fa/ z x 0 go+ :5 x left y\r sl+ %ot1 =ev] & ev]1 )\t /opp+1 unless x bump$ into a /> or some?+4 ,on e>? ! reason x /ops aft] a :ile is t x is bump+ into some?+ all ! "t--into ! p>ticles ( air :ile x is 9 ! air1 & f9ally aga9/ ! e>? :5 x is pull$ to ! gr\nd by gravity4 ,if y ?rew a ball on ! moon1 ! p]son :o caught x w\ld h to h a v ?ick mitt to protect 8 h&1 & x w\ld nev] be safe to cat* a batt$ fly4 ,= !re is no air on ! moon1 & !re=e no?+ w\ld sl[ ! ball d[n until x hit some?+2 & x w\ld be go+ z h>d & fa/ :5 x /ruck ! h& ( ! "o :o caught x z :5 x left y\r h& or ! bat4 ,illu/ration3 ,,fig4 #cd4 ,:5 ! pap] is j]k$ out1 ! glass ( wat] does n move4 ,,try ,,^! ,,exp]im5ts3 ,,exp]im5t #bc4 ,fill a glass almo/ to ! brim ) wat]4 ,lay a smoo? piece ( writ+ pap] #aj or #aa in*es long on a smoo? table1 plac+ x ne> ! edge ( ! table4 ,set ! glass ( wat] on ! pap] ne> its inn] edge 7,fig4 #cd74 ,take hold ( ! edge ( ! pap] t is ne> ! edge ( ! table4 ,move y\r h& a little t[>d ! glass s t ! pap] is some:at b5t4 ,!n1 keep+ y\r h& ne> ! level ( ! table1 sudd5ly j]k ! pap] out f "u ! glass4 ,if y give a quick en\gh j]k & keep y\r h& ne> ! level ( ! table1 n a drop ( wat] w spill & ! glass w /ay almo/ exactly :]e x 04 ,?is is because ! glass ( wat] has in]tia4 ,x 0 /&+ /ill1 & s x t5ds to rema9 /&+ /ill4 ,y\r j]k 0 s sudd5 t !re 0 n "t to ov]come ! in]tia ( ! glass ( wat]2 s x /ay$ :]e x 04 ,,exp]im5t #bd4 ,h a boy on roll] skates skate d[n ! hall or sidewalk t[>d y & h him beg9 to coa/ z he comes ne>4 ,:5 he rea*es y1 put out y\r arm & try to /op him4 ,notice h[ mu* =ce x takes to /op him 9 spite ( ! fact t he is no long] pu%+ himself along4 ,n[ let ! boy skate t[>d y aga91 coa/+ z be=e2 b ?is "t h him sw+ himself ar\nd a corn] by tak+ hold ( y z he passes4 ,notice h[ mu* =ce x takes j to *ange ! direction 9 :i* he is mov+4 ,illu/ration3 ,,fig4 #ce4 ,:5 a boy is mov+ rapidly1 x takes =ce to *ange ! direction ( 8 motion4 ,y see ! boy's in]tia makes him t5d to keep go+ /raight ahead at ! same spe$2 x resi/s any *ange ei!r 9 ! spe$ or ! direction ( 8 motion4 ,s x takes a good deal ( =ce ei!r to /op him or to turn him4 ,if1 on ! o!r h&1 y _h no in]tia1 y c\ld nei!r h /opp$ him nor turn$ him2 he w\ld h swept y "r along ) him4 ,x 0 because in]tia made y t5d to rema9 /ill1 t y c\ld ov]come "p ( 8 in]tia4 ,at ! same "t he ov]came "p ( y\r in]tia1 = he made y move a little4 ,in]tia is ! t5d5cy ( a ?+ to keep on go+ =ev] 9 ! same direction if once x is />t$1 or to /& /ill =ev] unless some?+ />ts x4 ,if mov+ ?+s did n h in]tia 7if !y did n t5d to keep "r on mov+ 9 ! same direction =ev] or until some?+ *ang$ _! motion71 y c\ld n ?r[ a ball2 ! second y let g ( x1 x w\ld /op & fall to ! gr\nd4 ,y c\ld n %oot a bullet any di/ance2 z soon z ! gases ( ! gunp[d] _h /opp$ pu%+ aga9/ x1 x w\ld /op dead & fall4 ,!re w\ld be no ne$ ( brakes on tra9s or automobiles2 ! in/ant ! /eam or gasol9e 0 %ut (f1 ! tra9 or auto w\ld come to a dead /op4 ,b y w\ld n be j]k$ 9 ! lea/ by ! /opp+1 because z soon z ! automobile or tra9 /opp$1 y\r body too w\ld /op mov+ =w>d4 ,y\r automobile c\ld ev5 cra% into a build+ )\t y\r be+ j>r$4 ,= :5 ! ma*9e came to a sudd5 /op1 y w\ld n be ?r[n =w>d at all1 b w\ld sit calmly 9 ! undamag$ automobile4 ,if y sat 9 a sw+ & "s "o ran "u y1 y w\ld keep go+ up till he let g1 & !n y w\ld be pull$ d[n by gravity j z y n[ are4 ,b j z soon z ! sw+ 0 /raight up & d[n y w\ld /op2 !re w\ld be no in]tia to make y keep on sw++ back & up4 ,if ! in]tia ( mov+ ?+s /opp$1 ! clocks w\ld no long] run1 ! p5dulums w\ld no long] sw+1 nor ! balance :eels turn2 no?+ c\ld be ?r[n2 x w\ld be impossible to jump2 !re w\ld cease to be waves on ! ocean2 & ! moon w\ld come tumbl+ to ! e>?4 ,! e>? w\ld /op sp9n+2 s !re w\ld be no *ange f day to night2 & x w\ld /op sw++ ab\t 9 its orbit & />t on a ru% t[>d ! sun4 ,b !re is always in]tia4 ,& all ?+s ev]y:]e & all ! "t t5d to rema9 /ock /ill if !y are /ill1 until "s =ce makes !m move2 & all ?+s t are mov+ t5d to keep on mov+ at ! same spe$ & 9 ! same direction1 until some?+ /ops !m or turns !m 9 ano!r direction4 ,,application #bj4 ,expla9 :y y %\ld face =w>d :5 alight+ f a /reet c>2 :y a croquet ball keeps roll+ aft] y hit x2 :y y feel a jolt :5 y jump d[n f a high place4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #ha4 ,x is mu* easi] to erase *>coal draw+s ?an wat]-color pa9t+s4 #hb4 ,:5 an elevator />ts d[n sudd5ly y feel light] = a mom5t1 :ile if x />ts up quickly y feel heavi]4 #hc4 ,y c draw a nail ) a claw hamm] :5 y c\ld n possibly pull x ) y\r h& ev5 if y c\ld get hold ( x4 #hd4 ,:5 an automobile bumps into any?+1 ! p 9 ! front seat are (t5 ?r[n =w>d ?r\gh ! w9d %ield4 #he4 ,c]ta9 weight$ dolls w rise & /& upright1 no matt] 9 :at position y lay !m d[n4 #hf4 ,"s automobile tires h little rubb] cups all ov] !m :i* are suppos$ to make ! tires cl+ to ! pavem5t & ?us prev5t skidd+4 #hg4 ,x is h>d to move b$s & bureaus :i* h no ca/ors or glid]s4 #hh4 ,:5 y jump (f a mov+ /reet c>1 y lean back4 #hi4 ,all wat] fl[s t[>d ! oceans soon] or lat]4 #ij4 ,y c skate on ice1 b n on a sidewalk1 ) ice skates4 ,,section #ab4 ,c5trifugal =ce4 ,:y does n ! moon fall d[n to ! e>?8 ,:y w a lasso g s f> aft] x is :irl$8 ,:y does a top /& on its po9t :ile x is sp9n+8 ,if c5trifugal =ce sudd5ly /opp$ act+1 y w\ld at fir/ n notice any *ange4 ,b if y happ5$ to get into an automobile & rode d[n a muddy /reet1 y w\ld be delight$ to f9d t ! mud did n fly up f ! :eels z y sp$ along4 ,& :5 y w5t ar\nd a slipp]y corn]1 y\r automobile w\ld n skid 9 ! lea/4 ,if a dog came out ( a pool ( wat] & %ook himself :ile c5trifugal =ce 0 n act+1 ! wat]1 in/ead ( fly+ (f 9 e direction1 w\ld m]ely drip d[n to ! gr\nd z if ! dog 7 n %ak+ himself at all4 ,a c[boy w\ld f9d t he c\ld no long] ?r[ 8 lasso by :irl+ x ar\nd 8 head4 ,a boy try+ to sp9 8 top w\ld discov] t ! top w\ld n /& on its po9t :ile sp9n+1 any bett] ?an :5 x 0 n sp9n+4 ,^! are little ?+s1 h[ev]4 ,mo/ p w\ld be q unconsci\s ( any *ange = "s "t4 ,!n1 z night came on & ! full moon rose1 x w\ld look z if x 7 gr[+ l>g] & l>g]4 ,x w\ld seem sl[ly to swell & swell until x fill$ ! :ole sky4 ,!n ) a /up5d\s cra% ! moon w\ld collide ) ! e>?4 ,e "o w\ld be in/antly kill$4 ,& x w\ld be lucky = !m t !y 72 = if any p surviv$ ! %ock ( ! awful collision1 !y w\ld be roa/$ to dea? by ! heat produc$ by ! /rik+ toge!r ( ! e>? & ! moon4 ,moreov]1 ! e>? w\ld be :irl$ swiftly t[>d ! sun1 & a little lat] ! *>r$ e>? w\ld be swept into ! sun's va/1 tempe/u\s flames4 ,:5 we 7 talk+ ab\t in]tia1 we said t if !re 7 no in]tia1 ! moon w\ld tumble d[n to ! e>? & ! e>?1 too1 w\ld fall into ! sun4 ,t 0 because if !re 7 no in]tia !re w\ld be no c5trifugal =ce4 ,= c5trifugal =ce is n really a =ce at all1 b x is "o =m ( in]tia--! in]tia ( :irl+ ?+s4 ,d ?is exp]im5t3 ,,exp]im5t #be4 ,hold a pail half full ( wat] 9 "o h&4 ,sw+ x back & =? a c\ple ( times2 !n sw+ x swiftly =w>d1 up1 & on ar\nd1 br++ x d[n back ( y 7,fig4 #cf74 ,sw+ x ar\nd ?is way swiftly & ev5ly sev]al times1 f9ally /opp+ at ! beg9n+ ( ! up sw+4 ,x is c5trifugal =ce t keeps ! wat] 9 ! pail4 ,x dep5ds entirely on in]tia4 ,y see1 :ile ! pail is sw++ upw>d rapidly1 ! wat] is mov+ up & t5ds by its in]tia to keep "r on mov+ 9 ! same upw>d direction4 ,be=e y get x ov] y\r head1 ! t5d5cy ( ! wat] to keep on go+ up is s /rong t x pulls on y\r arm & h& & presses aga9/ ! bottom ( ! pail above x4 ,its t5d5cy to g on up is /rong] ?an ! d[nw>d pull ( gravity4 ,z y sw+ ! pail on backw>d1 ! wat] ( c\rse has to move backw>d1 too2 s n[ x t5ds to keep on mov+ backw>d2 & :5 ! pail is />t+ d[n beh9d y1 ! wat] is t5d+ to fly out 9 ! backw>d direction 9 :i* x has j be5 go+4 ,!re=e x /ill pu%es aga9/ ! bottom ( ! pail & pulls away f y\r %\ld]1 :i* is 9 ! c5t] ( ! circle ab\t :i* ! pail is mov+4 ,by ! "t y h swung ! pail on d[n1 ! wat] 9 x t5ds to keep go+ d[n1 & x is /ill pull+ away f y\r %\ld] & press+ aga9/ ! bottom ( ! pail4 ,illu/ration3 ,,fig4 #cf4 ,:y doesn't ! wat] spill out8 ,9 ?is way1 dur+ e in/ant ! wat] t5ds to keep go+ 9 ! direction 9 :i* x 0 go+ j ! in/ant be=e4 ,! result is t ! wat] keeps pull+ away f y\r %\ld] z long z y keep sw++ x ar\nd4 ,all :irl+ ?+s t5d to fly away f ! c5t] ab\t :i* !y are turn+4 ,?is is ! law ( c5trifugal =ce4 ,! e>?1 = example1 z x sw+s ar\nd ! sun1 t5ds to fly away f ! c5t] ( its orbit4 ,?is t5d5cy ( ! e>?--its c5trifugal =ce--keeps x f be+ drawn into ! sun by ! p[]ful pull ( ! sun's gravitation4 ,at ! same "t x is ?is gravitation ( ! sun t keeps ! e>? f fly+ (f into space1 :]e we %\ld all be froz5 to icicles & lo/ 9 ev]la/+ night4 ,= if ! sun's pull /opp$1 ! e>? w\ld fly (f z does a /one :irl$ f ! end ( a /r+1 :5 y let g ( ! /r+4 ,! moon1 9 l mann]1 w\ld fly away f ! e>? & sun if gravitation /opp$ pull+ x1 b x w\ld cra% into u if its c5trifugal =ce did n keep x at a safe di/ance4 ,h y ev] sat on a sp9n+ plat=m1 sometimes call$ ! social :irl1 9 an amusem5t p>k1 & tri$ to /ay on z x spun fa/] & fa/]8 ,x is c5trifugal =ce t makes y slide away f ! c5t] & (f at ! edge4 ,illu/ration3 ,,fig4 #cg4 ,an automobile race4 ,notice h[ ! track is bank$ to keep ! c>s f ov]turn+ on ! curves4 ,,h[ ,,cream ,,is ,,sep>at$ ,,f ,,milk ,,by ,,c5trifugal ,,=ce4 ,! heavi] ?+s are1 ! h>d] !y are ?r[n out by c5trifugal =ce4 ,milk is heavi] ?an cream1 z y "k f ! fact t cream rises & floats on top ( ! milk4 ,s :5 milk is put into a c5trifugal sep>ator1 a ma*9e t :irls x ar\nd v rapidly1 ! milk is ?r[n to ! outside h>d] ?an ! cream1 & ! cream !re=e /ays ne>] ! middle4 ,z ! b[l ( ! ma*9e :irls fa/]1 ! milk is ?r[n s h>d aga9/ ! outside t x flatt5s out & rises up ! sides ( ! b[l4 ,?us y h a l>ge holl[ cyl9d] ( milk on ! outside aga9/ ! wall ( ! b[l1 :ile ! :irl+ cream =ms a small] cyl9d] inside ! cyl9d] ( milk4 ,by putt+ a sp\t on ! ma*9e s t x rea*es ! inn] cyl9d]1 ! cream c be drawn (f1 :ile a sp\t n put 9 s f> w draw (f ! milk4 ,,:y ,a ,,sp9n+ ,,top ,,/&s ,,on ,,its ,,po9t4 ,:5 a top sp9s1 all ! p>ticles ( wood ( :i* ! top is made are ?r[n out & away f ! c5t] ( ! top1 or r !y t5d to g out & away4 ,& ! pull ( ^! p>ticles out f ! c5t] is /rong] ?an ! pull ( gravitation on ! edges ( ! top to make x tip ov]2 s x /&s upright :ile x sp9s4 ,sp9 a top & see h[ ?is is4 ,,application #ba4 ,expla9 h[ a motor cycli/ c ride on an almo/ p]p5dicul> wall 9 a circul> race track4 ,expla9 h[ ! e>? keeps away f ! sun1 :i* is always p[]fully pull+ ! e>? t[>d x4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #ia4 ,z y tight5 a screw x becomes h>d] to turn4 #ib4 ,!re is a process = p>tly dry+ food by :irl+ x rapidly 9 a p]=at$ cyl9d]4 #ic4 ,x is easi] to climb m\nta9s 9 hobnail$ %oes ?an 9 smoo?-sol$ ones4 #id4 ,:5 y bore a hole ) a brace & bit1 ! h& t turns ! brace goes ar\nd a circle _m times z l>ge z ! hole t is be+ bor$4 #ie4 ,! h&s ( "s p]sons become r$ & slightly swoll5 if !y sw+ !m :ile tak+ a long walk4 #if4 ,a fly:eel keeps an eng9e go+ betwe5 ! /rokes ( ! pi/on4 #ig4 ,9 dry p>ts ( ! c\ntry f>m]s break up ! surface ( ! soil frequ5tly1 z less wat] comes up to ! surface ?r\gh pulv]iz$ soil ?an w\ld come ?r\gh ! f9e pores ( cak$ e>?4 #ih4 ,aft] y h app>5tly clean$ a grease spot out ( a suit x (t5 reappe>s :5 y h worn ! suit a few days4 #ii4 ,mud flies up f ! back :eel ( a boy's bicycle :5 he rides along a wet /reet4 #ajj4 ,a typewrit] key goes d[n less ?an an in*1 yet ! type b> goes up ne>ly #e in*es4 ,,section #ac4 ,action & reaction4 ,h[ c a bird fly8 ,:at makes x /ay up 9 ! air8 ,:at makes a gun kick8 ,:y d y s9k :5 y /op swimm+8 ,:5ev] any?+ moves1 x pu%es some?+ else 9 an opposite direction4 ,:5 y r[ a boat y c notice ?is2 y see ! o>s pu%+ ! wat] backw>d to pu% ! boat =w>d4 ,also1 :5 y %oot a bullet =w>d y c feel ! gun kick backw>d2 or :5 y pull d[n h>d en\gh on a b>1 y\r body rises up & y *9 y\rself4 ,b ! law is j z true = ?+s :i* are n noticeable4 ,:5 y walk1 y\r feet pu% back aga9/ ! e>?2 & if ! e>? 7 n s enorm\s & y s small1 & if no "o else 7 pu%+ 9 ! opposite direction1 y w\ld see ! e>? sp9 back a little = ea* /ep y took =w>d1 j z ! big ball t a p]=m+ be> /&s on turns backw>d z ! be> tries to walk =w>d4 ,illu/ration3 ,,fig4 #ch4 ,! horse goes =w>d by pu%+ backw>d on ! e>? ) 8 feet4 ,! usual way ( say+ ?is is1 ,action & reaction are equal & opposite4 ,if y climb a rope1 ! upw>d movem5t ( y\r body is ! action2 b y h to pull d[n on ! rope to lift y\r body up4 ,?is is ! reaction4 ,)\t ?is law ( action & reaction no fi% c\ld swim1 no /eamboat c\ld pu% its way across ! wat]1 no bird c\ld fly1 no tra9 or ma*9e ( any k9d c\ld move =w>d or backw>d1 no man or animal c\ld walk or crawl4 ,! :ole _w ( liv+ ?+s w\ld be utt]ly p>alyz$4 ,illu/ration3 ,,fig4 #ci4 ,z he />ts to toss ! ball up1 w he weigh m or less8 ,:5 any?+ />ts to move1 x does s by pu%+ on some?+ else4 ,:5 y\r arms />t to move up1 !y d s by pu%+ y\r body d[n a little4 ,:5 y swim1 y pu% ! wat] back & d[n ) y\r arms & legs1 & ?is pu%es y\r body =w>d & up4 ,:5 a bird flies up into ! air1 x pu%es its body up by beat+ ! air d[n ) its w+s4 ,:5 an airplane :irs along1 its propell] fans ! air backw>d all ! "t4 ,/reet-c> tracks are kept %9y by ! :eels1 :i* slip a little z !y t5d to %ove ! track backw>d 9 mak+ ! c> move =w>d4 ,automobile tires we> out 9 mu* ! same way1--!y slip & are worn by friction z !y move ! e>? back 9 pu%+ ! automobile =w>d4 ,9 fact1 if !re are loose pebbles or mud on ! road1 y c see ! pebbles or mud fly back1 z ! :eels ( ! automobile beg9 to turn rapidly & give _! backw>d pu% to ! e>? b5ea?4 ,illu/ration3 ,,fig4 #dj4 ,action & reaction are equal2 :5 he pu%es =w>d on ! ropes1 he pu%es backw>d ) equal =ce on ! seat4 ,"h are a c\ple ( exp]im5ts t w %[ y action & reaction m cle>ly3 ,,exp]im5t #bf4 ,/& on a plat=m scale & weigh y\rself4 ,:5 ! beam is exactly balanc$1 move y\r h&s upw>d & notice :e!r y weigh m or less :5 !y />t up4 ,n[ move !m d[nw>d2 :5 !y />t d[n1 d y weigh m or less8 ,toss a ball into ! air1 & wat* y\r weight :ile y are toss+ x4 ,does y\r body t5d to g up or d[n :ile y are mak+ ! ball g up8 ,,exp]im5t #bg4 ,g out into ! y>d & sit 9 a rope sw+4 ,/op ! sw+ entirely4 ,keep y\r feet (f ! gr\nd all ?r\gh ! exp]im5t4 ,n[ try to "w y\rself up 9 ! sw+2 t is1 make x sw+ by mov+ y\r legs & body & arms1 b n by t\*+ ! gr\nd4 7,try to make x sw+ =w>d & backw>d only2 :5 y try to sw+ sidewise1 ! di/ance betwe5 ! ropes spoils ! exp]im5t47 ,see if y c figure out :y ! sw+ w n move back & =?4 ,notice y\r bodily motions2 notice t :5 half ( y\r body goes =w>d1 half goes back2 :5 y pull back ) y\r h&s1 y pu% y\r body =w>d4 ,if y wat* y\rself closely1 y w see t e backw>d motion is exactly balanc$ by a =w>d motion ( "s "p ( y\r body4 ,,application #bb4 ,expla9 :y y pu% =w>d aga9/ ! table to %ove y\r *air back f x2 :y a bird beats d[n ) its w+s aga9/ ! air to =ce itself up2 :y y pu% back on ! wat] ) y\r o>s to make a r[boat g =w>d4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #aja4 ,wat] comes up city pipes into y\r kit*54 #ajb4 ,:5 y try to pu% a heavy trunk1 y\r feet slip out f "u y & slide 9 ! opposite direction4 #ajc4 ,:5 y turn a bottle ( wat] upside d[n ) a small piece ( c>dbo>d laid ov] its m\?1 ! wat] /ays 9 ! bottle4 #ajd4 ,y c squeeze a ?+ v tightly 9 a vise4 #aje4 ,!re is a wat] game call$ log roll+2 two m5 /& on a log float+ 9 ! wat] & roll ! log ar\nd ) _! feet1 ea* "o try+ to make ! o!r lose 8 balance4 ,expla9 :y ! log rolls backw>d :5 ! man app>5tly runs =w>d4 #ajf4 ,! oil :i* fills up ! spaces betwe5 ! p>ts ( a duck's fea!rs keeps ! duck f gett+ wet :5 a h5 w\ld be soak$4 #ajg4 ,sl$s run on sn[ m easily ?an wagons d4 #ajh4 ,9 coa/+ d[n a hill1 x is difficult to /op at ! bottom4 #aji4 ,:5 y light a p9:eel1 ! :eel :irls ar\nd z ! p[d] burns1 & ! sp>ks fly (f 9 all directions4 #aaj4 ,y _c lift y\rself by y\r own boot /raps4 ,,section #ad4 ,ela/icity4 ,:at makes a ball b\nce8 ,h[ does a spr+bo>d help y dive8 ,:y are automobile & bicycle tires fill$ ) air8 ,suppose !re 7 a man :o 0 p]fectly ela/ic1 & :o made ev]y?+ he t\*$ p]fectly ela/ic4 ,=tunately !re is no su* p]son1 b suppose an ela/ic man did exi/3 ,he walks ) a spr+ & a b\nd2 8 feet b\nce up l rubb] balls ea* "t !y /rike ! e>?2 8 legs snap back into place aft] ea* /ep z if pull$ by a spr+4 ,if he /umbles & falls to ! gr\nd1 he b\nces back up into ! air )\t a sc>4 7,y see1 8 sk9 spr+s back into %ape ev5 if x is scrat*$1 s t a scrat* in/antly heals47 ,& he b\nces on & on =ev] )\t /opp+4 ,suppose y1 see+ 8 plight1 try to /op him4 ,s9ce we are pret5d+ t he makes ev]y?+ he t\*es ela/ic1 ! in/ant y t\* him y b\nce helplessly away 9 ! opposite direction4 ,y may ?9k y\r clo!s w be wr9kl$ by all ?is b\nc+ ab\t1 b s9ce we are imag9+ t y h caught ! ela/ic t\* f ! ela/ic man1 y\r clo!s :i* t\* y likewise become p]fectly ela/ic4 ,s no matt] h[ muss$ !y get1 !y promptly /raight5 out aga9 to ! condition !y 7 9 :5 y t\*$ ! ela/ic man4 ,if y notice t y\r %oe lace 0 unti$ j be=e y became ela/ic1 & y n[ try to tie x & tuck x 91 y f9d x mo/ unmanageable4 ,x insi/s ^u fly+ out ( y\r %oe & spr++ unti$ aga94 ,p]haps y\r hair 0 muss$ be=e y became ela/ic4 ,n[ x is impossible to comb x /raight2 ea* hair spr+s back l a f9e /eel wire4 ,if y take a h&k]*ief f y\r pocket to wipe y\r p]spir+ br[1 y f9d t x does n /ay unfold$4 ,z soon z x is spread out on y\r h&1 x snaps back to ! %ape & ! folds x _h :ile 9 y\r pocket4 ,suppose y b\nce up into an automobile = a ride4 ,! automobile1 n[ be+ made ela/ic by y\r magic t\*1 b\nds up into ! air at ! fir/ bump x /rikes1 & !reaft] x goes hopp+ d[n ! /reet 9 a mo/ di/ress+ mann]1 b\nc+ (f ! gr\nd l a rubb] ball ea* "t x comes d[n4 ,& ea* "t x bumps y are ?r[n (f ! seat into ! air4 ,y f9d x h>d to /ay 9 any new position4 ,y\r body always t5ds to snap back to ! position y 7 9 :5 y fir/ became ela/ic4 ,if y t\* a trott+ horse & x becomes ela/ic1 ! poor animal f9ds t 8 legs always /raight5 out to _! trott+ position1 :e!r he wants to walk or /& /ill or lie d[n4 ,imag9e ! plight ( a boy pit*+ a ball1 or "s "o yawn+ & /ret*+1 or a cl[n turn+ a som]sault1 if y t\* ea* ( ^! j 9 ! act & make him ela/ic4 ,_! bodies always t5d to snap back to ^! positions4 ,:5ev] ! cl[n wants to re/1 he has to get 9 ! som]sault position4 ,! boy pit*] sleeps 9 ! position ( w9d+ up to ?r[ ! ball4 ,! "o :o 0 yawn+ & /ret*+ has to be always on ! al]t1 because ! in/ant he /ops hold+ himself 9 "s o!r position1 8 m\? flies op51 8 arms fly out1 & e "o ?9ks he is bor$ to dea?4 ,y might t\* ! clay t a sculptor is mold+ & make x ela/ic4 ,! sculptor c mold all he pleases1 b ! clay is l rubb] & always returns at once to its orig9al %ape4 ,if y make a tree ela/ic :5 a man is *opp+ x d[n1 8 ax b\nces back f ! tree ) su* =ce z ne>ly to knock him ov]1 & no am\nt ( *opp+ makes s mu* z a la/+ d5t 9 ! tree4 ,suppose y /ep 9 "s mud4 ,! mud does n /ick to y\r %oes4 ,x b5ds d[n "u y\r weight1 b spr+s back to =m aga9 z soon z y\r weight is remov$4 ,& if y try to spread "s ela/ic butt] on bread1 no?+ w make ! butt] /ay spread4 ,! in/ant y remove y\r knife1 ! butt] rolls up aga9 into ! same k9d ( lump x 0 9 be=e4 ,z = *ew+ y\r bread1 y might z well try to *ew a rubb] b&4 ,y =ce y\r jaws op51 & !y snap back on ! bread all "r2 !n !y spr+ op5 aga91 & snap back & keep ?is up automatically until y make !m /op4 ,b = all ?is vigor\s *ew+ y\r bread looks z if x _h nev] be5 t\*$ by a too?4 ,sew+ is ab\t z difficult4 ,! ?read spr+s into a coil 9 ! %ape ( ! spool4 ,no hem /ays turn$2 ! clo? y try to sew spr+s into its orig9al folds 9 a mo/ exasp]at+ mann]4 ,on ! :ole1 a p]fectly ela/ic _w w\ld be a hopeless "o to live 94 ,ela/icity is ! t5d5cy ( a ?+ to g back to its orig9al %ape or size :5ev] x is =c$ into a diff]5t %ape or size4 ,a ?+ does n h to be s(t to be ela/ic4 ,/eel is v ela/ic2 t is :y good spr+s are almo/ always made ( /eel4 ,glass is ela/ic2 y "k h[ y c b\nce a glass m>ble4 ,rubb] is ela/ic1 too4 ,air is ela/ic 9 a diff]5t way2 x does n g back to its orig9al %ape1 s9ce x has no %ape1 b if x has be5 compress$ & ! pressure is remov$ x imm$iately exp&s aga92 s a football or any su* ?+ fill$ ) air is decid$ly ela/ic4 ,t is :y automobile & bicycle tires are fill$ ) air2 x makes ! be/ possible spr+s4 ,balls b\nce because !y are ela/ic4 ,:5 a ball /rikes ! gr\nd1 x is pu%$ out ( %ape4 ,s9ce x is ela/ic x tries imm$iately to come back to its =m] %ape1 & s pu%es out aga9/ ! gr\nd4 ,?is gives x su* a pu% upw>d t x flies back to y\r h&4 ,sometimes p confuse ela/icity ) action & reaction4 ,b ! diff]5ces betwe5 !m are v cle>4 ,action & reaction happ5 at ! same "t2 y\r body goes up at ! same "t t y pull d[n on a b> to *9 y\rself2 :ile 9 ela/icity a ?+ moves fir/ "o way1 !n ! o!r2 y ?r[ a ball d[n1 !n x comes back up to y4 ,ano!r diff]5ce is t 9 action & reaction "o ?+ moves "o way & ano!r ?+ is pu%$ ! o!r way2 :ile 9 ela/icity ! same ?+ moves fir/ "o way1 !n ! o!r4 ,if y press d[n on a spr+ scale ) y\r h&1 y are lift+ up y\r body a little to d x2 t is action & reaction4 ,b aft] y take y\r h& (f ! scale ! pan spr+s back up3 fir/ x 0 pu%$ d[n1 !n x spr+s back to its orig9al position2 x does ?is because ( ! ela/icity ( its spr+4 ,,application #bc4 ,expla9 :y basket balls are fill$ ) air2 :y spr+s are usually made ( /eel2 :y we use rubb] b&s to hold pap]s toge!r2 :y a toy balloon becomes small aga9 :5 y let ! air out4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+1 be+ especially c>eful n to confuse action & reaction ) ela/icity3 #aaa4 ,:5 y want to pu% y\r *air back f a table1 y pu% =w>d aga9/ ! table4 #aab4 ,! pans 9 :i* c&y is cool$ mu/ be greas$4 #aac4 ,good spr+s make a b$ com=table4 #aad4 ,pap] clips are made ( /eel or spr+ brass4 #aae4 ,a spr+ door lat* acts by itself if y close ! door tightly4 #aaf4 ,on a cold morn+1 y rub y\r h&s toge!r to w>m !m4 #aag4 ,if an electric fan is n fa/5$ 9 place & has n a heavy base1 x w move backw>d :ile x is go+4 #aah4 ,doors ) spr+s on !m w close aft] y4 #aai4 ,:5 y jump d[n on ! end ( a spr+bo>d1 x ?r[s y into ! air4 #abj4 ,y move y\r h&s backw>d to swim =w>d4 ,,note4 ,!re are really two k9ds ( ela/icity1 :i* h no?+ to d ) ea* o!r4 ,ela/icity ( =m is ! t5d5cy ( a ?+ to g back to its orig9al %ape1 z rubb] does4 ,if y make a d5t 9 rubb]1 x spr+s "r back to ! %ape x _h be=e4 ,ela/icity ( volume is ! t5d5cy ( a sub/ance to g back to its orig9al size1 z lead does4 ,if y manage to squeeze lead into a small] space1 x w spr+ "r back to ! same size z soon z y /op press+ x on all sides4 ,b a d5t 9 lead w /ay !re2 x has little ela/icity ( =m4 ,air & wat]--all liquids1 9 fact--h a great deal ( ela/icity ( volume1 b practically no ela/icity ( =m4 ,!y d n t5d to keep _! %ape1 b !y d t5d to fill ! same am\nt ( space4 ,putty & clay likewise h v little ela/icity ( =m2 :5 y *ange _! %ape1 !y /ay *ang$4 ,jelly & /eel & glass h a great deal ( ela/icity ( =m4 ,:5 y d5t !m or twi/ !m or 9 any way *ange _! %ape1 !y g "r back to _! fir/ %ape z soon z !y c4 ,:5 we imag9$ a man ) an ela/ic t\*1 we 7 imag9+ a man :o gave ev]y?+ he t\*$ p]fect ela/icity ( =m4 ,x is ela/icity ( =m t mo/ p mean :5 !y talk ab\t ela/icity4 ,,*apt] ,,f\r ,,heat ,,section #ae4 ,heat makes ?+s exp&4 ,h[ does a !rmomet] "w8 ,:at makes ! m]cury rise 9 x8 ,:y does heat make ?+s get l>g]8 ,:5 we look at objects ?r\gh a microscope1 !y appe> mu* l>g] & 9 _m cases we are able to see ! small] p>ts ( :i* !y are made4 ,if we _h a microscope s p[]ful t x made a t9y speck ( du/ look z big z a m\nta9 7( c\rse no su* microscope exi/s71 & if we look$ ?r\gh ?is imag9>y microscope at a piece ( iron1 we %\ld f9d to our surprise t ! p>ticles 7 n /&+ /ill4 ,! iron w\ld probably look z if x 7 fairly alive ) millions ( t9y specks mov+ back & =?1 back & =?1 fa/] ?an ! flutt] ( an insect's w+s4 ,^! t9y mov+ ?+s are molecules4 ,ev]y?+ 9 ! _w is made ( !m4 ,x seems /range t we %\ld "k ?is1 s9ce !re really are no microscopes ne>ly p[]ful en\gh to %[ ! molecules to u4 ,yet sci5ti/s "k a great deal ab\t !m4 ,!y h devis$ all sorts ( elaborate exp]im5ts--v accurate ones--& h te/$ ! !ories ab\t molecules 9 _m ways4 ,!y h said1 = in/ance1 ,n[1 if ?is ?+ is made ( molecules1 !n x w gr[ l>g] :5 we make ! molecules move fa/] by heat+ x4 ,!n !y heat$ x--9 y\r next exp]im5t y w see :at happ5$4 ,?is is only "o ( ?\s&s ( exp]im5ts !y h p]=m$1 measur+ ov] & ov] aga91 ) ! greate/ c>e1 exactly h[ mu* an object exp&$ :5 x 0 heat$ a c]ta9 am\nt2 exactly h[ mu* heat 0 ne$$ to *ange wat] to /eam2 exactly h[ f> a piece ( /eel ( a c]ta9 size & %ape c\ld b5d )\t break+2 exactly h[ cry/als =m--& s on & s on4 ,& !y h always f\nd t ev]y?+ acts z if x 7 made ( mov+ molecules4 ,_! exp]im5ts h be5 s c>eful & sci5ti/s h f\nd out s mu* ab\t :at seem to be molecules1--h[ l>ge !y are1 :at !y probably weigh1 h[ fa/ !y move1 & ev5 :at !y are made (1--t almo/ no "o has any d\bt left t fa/-mov+ molecules make up ev]y?+ 9 ! _w4 ,illu/ration3 ,,fig4 #da4 ,a !rmomet]4 ,to g back1 !n3 if we look$ at a piece ( iron "u a microscope t w\ld %[ u ! molecules1--& rememb]1 no su* p[]ful microscope c\ld exi/1--we %\ld see ^! quiv]+ p>ticles1 & no?+ m4 ,!n if "s "o heat$ ! iron :ile we wat*$ ! molecules1 or if ! sun %one on x1 we %\ld see ! molecules move fa/] & fa/] & sep>ate f>!r & f>!r4 ,t is :y heat exp&s ?+s4 ,:5 ! molecules 9 an object move f>!r ap>t1 naturally ! object exp&s4 ,heat is ! motion ( ! molecules4 ,:5 ! molecules move fa/] 7t is1 :5 ! iron gr[s hott]71 !y sep>ate f>!r & ! iron swells4 ,illu/ration3 ,,fig4 #db4 ,a !rmomet] made ( a flask ( wat]4 ,x does n %[ ! exact degree ( heat ( ! wat]1 b x does %[ :e!r ! wat] is hot or cold4 ,,h[ ,,we ,,c ,,tell ,,! ,,temp]ature ,,by ,,read+ ,a ,,!rmomet]4 ,! m]cury 7quicksilv]7 9 ! bulb ( ! !rmomet] l ev]y?+ else exp&s 7swells7 :5 x becomes w>m4 ,x is %ut 9 tightly on all sides by ! glass1 except = ! little op5+ into ! tube above4 ,:5 x exp&s x mu/ h m room1 & ! only space into :i* x c move is up 9 ! tube4 ,s x rises 9 ! tube4 ,illu/ration3 ,,fig4 #dc4 ,w ! hot ball g ?r\gh ! r+8 ,wat] w d ! same ?+4 ,y c make a sort ( !rmomet]1 us+ wat] in/ead ( m]cury1 & wat* ! wat] exp& :5 y heat x4 ,"h are ! directions = do+ ?is3 ,illu/ration3 ,,fig4 #dd4 ,:5 ! wire is cold1 x is fairly tight4 ,,exp]im5t #bh4 ,fill a flask to ! top ) wat]4 ,put a piece ( glass tub+ ?r\gh a /opp]1 lett+ ! tube /ick #h or #aj in*es above ! top ( ! /opp]4 ,put ! /opp] into ! flask1 keep+ out all air2 ! wat] may rise #b or #c in*es 9 ! glass tube4 ,dry ! flask on ! outside & put x on a scre5 on ! /ove or r+ /&1 & heat x4 ,wat* ! wat] 9 ! tube4 ,:at effect does heat h on ! wat]8 ,"h are two int]e/+ exp]im5ts t %[ h[ solid ?+s exp& :5 !y are heat$3 ,,exp]im5t #bi4 ,! brass ball & brass r+ %[n 9 ,figure #dc are call$ ! expansion ball & r+4 ,try pu%+ ! ball ?r\gh ! r+4 ,n[ heat ! ball ov] ! flame = a m9ute or two--x %\ld n be r$ hot--& try aga9 to pass x ?r\gh ! r+4 ,heat bo? ball & r+ = a %ort "t4 ,does heat+ exp& ! r+8 ,,exp]im5t #cj4 ,g to ! electric app>atus 7describ$ on page #cgi7 & turn on ! swit* t lets ! electricity fl[ ?r\gh ! long resi/ance wire4 ,wat* ! wire z x becomes hot4 ,,application #bd4 ,a woman br\ght me a glass-/opp]$ bottle ( smell+ salts & ask$ me if ,i c\ld op5 x4 ,! /opp] 0 9 s tightly t ,i c\ld n pull x out4 ,i might h done any ( ! foll[+ ?+s3 ,tri$ to pull ! /opp] out ) a pair ( pli]s2 plung$ ! bottle up to ! neck 9 hot wat]2 plung$ x 9 ice-cold wat]2 tri$ to loos5 ! /opp] by tapp+ x all ar\nd4 ,:i* w\ld h be5 ! be/ way or ways8 ,illu/ration3 ,,fig4 #de4 ,b notice h[ x sags :5 x is hot4 ,,application #be4 ,i us$ to buy a qu>t ( milk ea* ev5+ f a f>m] j aft] he _h milk$4 ,he cool$ mo/ ( ! milk z soon z x 0 /ra9$1 to make x keep bett]4 ,he ask$ me if ,i want$ my qu>t be=e or aft] x 0 cool$4 ,ei!r way he w\ld fill 8 qu>t measure brim full4 ,:i* way w\ld ,i h receiv$ m milk = my money8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #aba4 ,billi>d balls w reb\nd f ea* o!r & f ! edges ( ! table aga9 & aga9 & f9ally /op4 #abb4 ,9 wa%+ a tumbl] 9 hot wat] x is necess>y to lay x 9 sidewise & wet x all ov]1 inside & out1 to keep x f crack+2 if x is ?ick 9 "s p>ts & ?9 9 o!rs1 l a cut-glass tumbl]1 x is n safe to wa% x 9 hot wat] at all4 #abc4 ,! sw++ ( ! moon ar\nd ! e>? keeps ! moon f fall+ to ! e>?4 #abd4 ,a fire 9 a grate creates a draft up ! *imney4 #abe4 ,telegraph wires & wire f5ces put up 9 ! summ] mu/ n be /rung too tightly4 #abf4 ,c&y usually draws 9 some:at f ! edge ( ! pan z x h>d5s4 #abg4 ,a meat *opp] c be screw$ to a table m tightly ?an y c possibly pu% x on4 #abh4 ,a floor cov]$ ) l9oleum is m easily kept clean ?an a pla9 wood floor4 #abi4 ,r\gh seams on ! inside ( clo!s *afe y\r sk94 #acj4 ,y c take ! top (f a bottle ( soda pop ) an op5] t w pry x up1 b y _c pull x (f ) y\r f+]s4 ,,section #af4 ,cool+ f expansion4 ,we get our heat f ! sun2 !n :y is x s cold up on ! m\nta9 tops8 ,:at is coldness8 ,"h is an int]e/+ & r /range ?+ ab\t heat & expansion4 ,al?\gh heat exp&s ?+s1 yet expansion does n heat !m4 ,on ! contr>y1 if a ?+ exp&s )\t be+ heat$ f an outside s\rce1 x actually gets cold6 ,y see1 9 ord] to exp&1 x has to pu% ! air or some?+ else aside1 & x actually uses up ! en]gy ( its own heat to d ?is4 ,y w und]/& ?is bett] aft] y d ! next exp]im5t4 ,,exp]im5t #ca4 ,wet ! inside ( a te/ tube4 ,hold ! m\? ( ! te/ tube aga9/ ! op5+ ( a c>bon dioxid tank4 ,op5 ! valve ( ! tank ) ! wr5* & let ! compress$ gas ru% out into ! te/ tube until ! m\? ( ! te/ tube is :ite4 ,%ut (f ! valve4 ,feel y\r te/ tube4 ,:at has happ5$ is ?is3 ,! gas 0 tightly compress$ 9 ! tank4 ,x 0 n cold2 t is1 x _h "s heat 9 x1 z ev]y?+ has4 ,:5 y let x loose1 x us$ up mu* ( its heat 9 pu%+ ! air 9 ! te/ tube & all ar\nd x out ( ! way4 ,9 ?is way x lo/ its heat1 & !n x became cold4 ,cold means abs5ce ( heat1 z d>k means abs5ce ( light4 ,s :5 ! compress$ gas us$ up its heat 9 pu%+ ! air out ( its way1 x became s cold t x froze ! wat] 9 y\r te/ tube4 ,illu/ration3 ,,fig4 #df4 ,! expansion ( ! compress$ gas freezes ! moi/ure on ! tube4 ,,"o ,,reason ,,:y ,,x ,,is ,,always ,,cold ,,high ,,up ,,9 ,,! ,,air4 ,ev5 on hot summ] days aviators :o fly high suff] f ! cold4 ,y might ?9k t !y w\ld get w>m] z !y w5t up ne>] ! sun2 "o reason t !y get cold] in/ead is ?is3 ,z y saw 9 ! la/ exp]im5t1 a gas t exp&s gets v cold4 ,air is a k9d ( gas4 ,& :5ev] air rises to :]e !re is n s mu* air cr[d+ d[n on x f above1 x exp&s4 ,s ! air t rises high & exp&s gets v cold4 ,consequ5tly m\nta9s :i* rea* up into ?is high1 cold air are sn[ cov]$ all ! ye> r\nd2 & aviators :o fly high suff] ke5ly f ! cold4 ,!re are sev]al reasons = ?is coldness ( ! high air4 ,?is is j "o ( !m4 ,,application #bf4 ,expla9 :y air usually cools :5 x rises2 :y high m\nta9 tops are always cov]$ ) sn[4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #aca4 ,y %\ld n fill a teakettle brim full ( cold wat] :5 y are go+ to put x on ! /ove4 #acb4 ,x is h>d] to erase an ink m>k ?an a p5cil m>k4 #acc4 ,be>+s ( good wat*es1 :]e !re is con/ant rubb+ on ! p>ts1 are made ( v h>d jewels4 #acd4 ,y feel light] = an in/ant :5 y are 9 an elevator :i* />ts d[n sudd5ly4 #ace4 ,:5 m5 lay cem5t sidewalks1 !y almo/ always make cracks across !m e few feet4 #acf4 ,to cool hot c(fee "o sometimes bl[s on x4 #acg4 ,x is mu* easi] to turn ! lat* ( a door ) ! knob ?an ) ! sp9dle :5 ! knob is (f4 #ach4 ,pat5t-lea!r %oes d n soil z easily z pla9 lea!r %oes4 #aci4 ,we use rubb] b&s to hold ?+s toge!r tightly4 #adj4 ,z air goes up x usually cools4 ,,section #ag4 ,freez+ & melt+4 ,:5 wat] freezes 9 a pipe1 :y does ! pipe bur/8 ,:at is liquid air8 ,:y does n ! wire 9 an electric lamp melt :5 x is r$ hot8 ,suppose we look$ at a piece ( ice ?r\gh ! imag9>y microscope t %[s u ! molecules4 ,! ice molecules w\ld be diff]5t f ! iron molecules 9 size1 b !y w\ld be vibrat+ back & =? 9 exactly ! same way1 only ) less motion4 ,x is because !y h less motion t we say ! ice is cold] ?an ! iron4 ,!n let u suppose t ! sun 0 %9+ on ! ice :ile we wat*$ ! ice molecules4 ,fir/ we %\ld see movem5ts ( ! ice molecules become gradually m rapid1 j z ! iron molecules did :5 ! iron 0 w>m$4 ,!n1 z !y mov$ fa/] & fa/]1 !y w\ld beg9 to bump into ea* o!r & g ar\nd e :i* way1 ea* molecule bump+ fir/ into "o neighbor1 !n into ano!r1 & b\nc+ back 9 a new direction aft] ea* collision4 ,?is is :at causes ! ice to melt4 ,:5 its molecules no long] g back & =? 9 ! same pa? all ! "t1 ! ice no long] keeps its %ape1 & we call x wat]--a liquid4 ,almo/ all solid sub/ances w melt :5 !y are heat$4 ,or1 to put x ! o!r way ar\nd1 e liquid w freeze solid if x gets cold en\gh4 ,ev5 liquid air 7:i* is ord9>y air cool$ & compress$ until x runs l wat]7 c be froz5 into a solid *unk4 ,"s ?+s w melt :ile !y are /ill v cold2 solid air1 = in/ance1 melts at a temp]ature t w\ld freeze y into an icicle be=e y c\ld c\nt t54 ,o!r ?+s1 su* z /ones1 are melt$ only by t]rific heat4 ,:5 ! little p>ticles ( wat] t make up ! cl\ds become v cold1 !y freeze z !y ga!r & s make sn[flakes4 ,:5 ! little p>ticles ( wat] 9 ! air1 t usually make dew1 freeze :ile !y are ga!r+ on a blade ( grass1 we call x fro/4 ,:5 ra9drops are c>ri$ up into cold]1 high] air :ile !y are =m+1 !y freeze & turn to hail4 ,:5 sn[ or fro/ or hail or ice is heat$1 x melts & turns back to wat]4 ,illu/ration3 ,,fig4 #dg4 ,:y did ! bottle break :5 ! wat] 9 x turn$ to ice8 ,b "h is a /range fact3 al?\gh heat usually exp&s ?+s1 wat] exp&s :5 x freezes4 ,l ev]y?+ else1 h[ev]1 wat] also exp&s :5 x becomes hot1 z y f\nd :5 y made a k9d ( !rmomet]1 us+ a flask ( wat] & a glass tube4 ,b if y %\ld put t flask into a freez+ mixture ( ice & salt1 y w\ld f9d t :5 ! wat] became v cold x w\ld beg9 to exp& a little imm$iately be=e x froze4 ,& x is v lucky = u t wat] does exp& :5 x freezes1 because if x did n1 ice w\ld be heavi] ?an wat] is4 ,b s9ce ! wat] exp&s z x freezes1 ice weighs less ?an wat] & floats4 ,& t is :y lakes & oceans & riv]s freeze ov] ! top & d n freeze at ! bottom4 ,if !y froze f ! bottom up1 z !y w\ld if ! ice sank z x =m$1 e riv] & lake w\ld be solid ice 9 ! w9t]4 ,all ! h>bors outside ! tropics w\ld probably be ice-b\nd all w9t] long4 ,& ! ice 9 ! bottom ( ! lakes & riv]s & 9 ! ocean w\ld probably nev] melt4 ,s 9 ! case ( freez+ wat]1 & 9 ! case ( a c\ple ( metals1 !re is a po9t :]e coldness1 n heat1 makes ?+s exp&4 ,,exp]im5t #cb4 ,take a ket*up bottle ) a screw cap & a cork t fits tightly4 ,fill x to ! top ) wat]2 put a long p9 beside ! cork :ile y ins]t x1 s t ! wat] c be cr[d$ out z ! cork goes d[n2 !n :5 y h pu%$ ! cork 9 tightly1 pull out ! p94 ,screw ! cap on ! bottle s z to hold ! cork fa/4 ,put ! bottle 9 a pail or box1 & pack ice & salt ar\nd x4 ,)9 an h\r y %\ld be able to see :at ! freez+ wat] does to ! bottle4 ,,application #bg4 ,expla9 :y ice is light] ?an wat]2 :y we h no sn[ 9 summ]4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #ada4 ,seal+ wax is held ov] a c&le flame be=e x is appli$ to a lett]4 #adb4 ,automobile tires tight5 ^u a sudd5 *ange f cold wea!r to hot4 #adc4 ,:5 pap] has be5 roll$1 x t5ds to curl up aga9 aft] be+ unroll$4 #add4 ,seats runn+ across a c> are mu* m com=table :5 a c> />ts & /ops1 ?an are seats runn+ along ! sides4 #ade4 ,y _c siphon wat] f a l[ place to a high] "o4 #adf4 ,c&les get s(t 9 hot wea!r4 #adg4 ,meteorites fall to ! e>? f ! sky4 #adh4 ,:5 y pres]ve fruit & p\r ! hot fruit into ! j>s1 y fill ! j>s brim full & screw on ! cap air-tight2 yet a few h\rs lat] ! fruit does n fill ! j>s2 !re is "s empty space betwe5 ! top ( ! fruit & ! cov]4 #adi4 ,wat] pipes bur/ 9 ! w9t] :5 x is v cold4 #aej4 ,:5 p want to make iron ca/+s1 !y fir/ melt ! iron1 !n p\r x into molds4 ,!y leave x 9 ! molds until cold4 ,aft] t ! iron holds ! %ape ( ! molds4 ,expla9 :y ! iron *anges f a liquid to a solid4 ,,section #ah4 ,evaporation4 ,:y is x t :5 ink is spill$ x dries up1 b :5 x is 9 ! bottle x does n dry up8 ,:at put ! salt into ! ocean8 ,:y d y feel cold :5 y get out ( ! ba?tub8 ,wet clo!s get dry :5 !y are hung on ! clo!s-l9e4 ,! wat] 9 !m evaporates4 ,x turns to invisible vapor & disappe>s into ! air4 ,wat] & all liquids evaporate :5 !y are long expos$ to ! air4 ,if !y didn't--well1 let u imag9e :at ! _w w\ld be l if all evaporation %\ld sudd5ly /op3 ,y f9d t y\r face is p]spir+ & y\r h&s z well4 ,y wipe !m on y\r h&k]*ief1 b soon !y are moi/ aga91 no matt] h[ cool ! wea!r4 ,aft] wip+ !m a few m times y\r h&k]*ief becomes soak+ wet1 & y hang x up to dry4 ,!re may be a good breeze /irr+1 yet y\r h&k]*ief does n get dry4 ,by ?is "t ! p]spiration is runn+ (f y\r face & h&s1 & y\r und]clo!s are gett+ dr5*$ ) p]spiration4 ,illu/ration3 ,,fig4 #dh4 ,an evaporat+ di%4 ,y hurry into ! h\se1 *ange y\r clo!s1 ba! & wipe y\rself dry ) a t[el4 ,:5 y f9d t y\r wet ?+s are n dry+1 & t y\r dry ones are rapidly becom+ moi/1 y ha/ily build a fire & hang y\r clo!s beside x4 ,no use1 y\r clo!s rema9 z wet z ev]4 ,if y get !m v hot ! moi/ure 9 !m w boil & turn to /eam1 ( c\rse1 b ! /eam w all turn back to wat] z soon z x cools a little & ! drops w cl+ to y\r clo!s & to ev]y?+ ar\nd ! room4 ,y w h to get us$ to liv+ 9 wet clo!s4 ,y won't cat* cold1 ?\gh1 s9ce !re is no evaporation to use up y\r heat4 ,b ! wat] problem outside is n "o ( m]e inconv5i5ce4 ,x nev] ra9s4 ,h[ c x :5 ! wat] f ! oceans _c evaporate to =m cl\ds8 ,little by little ! riv]s beg9 to run dry--!re is no ra9 to fe$ !m4 ,no fog bl[s 9 f ! sea2 no cl\ds cool ! sun's gl>e2 no dew moi/5s ! grass at night2 no fro/ %[s ! com+ ( cold wea!r2 no sn[ comes to cov] ! m\nta9s4 ,9 "t !re is no wat] left 9 ! riv]s2 e lake ) an outlet runs dry4 ,!re are no spr+s1 &1 aft] a :ile1 no wells4 ,p h to live on juicy plants4 ,! crops =tunately require v little moi/ure1 s9ce none evaporates f !m or f ! gr\nd 9 :i* !y gr[4 ,& ! p d n ne$ ne>ly z mu* wat] to dr9k4 ,little by little1 h[ev]1 ! wat] all soaks too deep into ! gr\nd = ! plants to get x4 ,gradually ! cont95ts become great des]ts1 & all life p]i%es f ! l&4 ,all ^! ?+s w\ld really happ51 & _m m *anges besides1 if wat] did n evaporate4 ,yet ! evaporation ( wat] is a v simple occurr5ce4 ,z ! molecules ( any liquid b\nce ar\nd1 "s get hit h>d] ?an o!rs4 ,^! are %ot (f f ! re/ up into ! air1 & get too f> away to be drawn back by ! pull ( ! molecules beh9d4 ,?is %oot+ away ( "s ( ! molecules is evaporation4 ,& s9ce x takes heat to s5d ^! molecules fly+ (f1 ! liquid t is left beh9d is cold] because ( ! evaporation4 ,t is :y y are always cold aft] y leave ! ba?tub until y are dry4 ,! wat] t evaporates f y\r body uses up a good deal ( y\r heat4 ,illu/ration3 ,,fig4 #di4 ,diagram illu/rat+ h[ 9 ! evaporation ( wat] "s ( ! molecules %oot (f into ! air4 ,gasol9e evaporates m quickly ?an wat]4 ,t is :y y\r h&s become s cold :5 y get !m wet ) gasol9e4 ,s9ce heat is requir$ to evaporate a liquid1 ! quicke/ way to dry any?+ is to w>m x4 ,t is :y y hang clo!s 9 ! sun or by ! /ove to dry4 ,try ^! exp]im5ts3 ,,exp]im5t #cc4 ,read a !rmomet] t has be5 expos$ to ! room air4 ,n[ dip x 9 wat] t is w>m] ?an ! air1 tak+ x out aga9 at once4 ,wat* ! m]cury4 ,does ! !rmomet] regi/] a high] or a l[] temp]ature ?an x did at ! beg9n+8 ,:at is tak+ up ! heat f ! m]cury8 ,,exp]im5t #cd4 ,put a few drops ( wat] 9 ea* ( two evaporat+ di%es4 ,leave "o cold2 w>m ! o!r ov] ! burn]1 b d n heat x to boil+4 ,:i* evaporates m quickly8 ,,:y ,,! ,,sea ,,is ,,salt4 ,y rememb] v>i\s fairy /ories ab\t :y ! sea is salt4 ,= a long "t ! saltness ( ! sea puzzl$ p4 ,b ! explanation is simple4 ,z ! wat] f ! ra9s seeps ?r\gh ! soil & rocks1 x dissolves ! salt 9 !m & cont9ually c>ries "s ( x into ! riv]s4 ,s ! wat]s ( ! riv]s always c>ry a v little salt ) !m out to sea4 ,! wat] 9 ! ocean evaporates & leaves ! salt beh9d4 ,= millions ( ye>s ?is has be5 go+ on4 ,s ! riv]s & lakes1 :i* h only a little salt 9 !m1 keep add+ _! small am\nts to ! sea1 & once 9 ! sea ! salt nev] c get out4 ,! oceans nev] get any full] ( wat]1 because wat] only fl[s into ! ocean z fa/ z x evaporates f ! ocean4 ,yet m salt goes into ! ocean all ! "t1 wa%$ d[n by ?\s&s ( /reams & riv]s4 ,s little by little ! ocean has be5 gr[+ m & m salty s9ce ! _w began4 ,illu/ration3 ,,fig4 #ej4 ,a view ( ! ,dead ,sea4 ,great ,salt ,lake & ! ,dead ,sea1 unlike mo/ lakes1 h no riv]s fl[+ out ( !m to c>ry ! salt & wat] away1 b riv]s fl[ into !m & br+ along small am\nts ( salt all ! "t4 ,!n ! wat] evaporates f ,great ,salt ,lake & ! ,dead ,sea1 leav+ ! salt beh9d2 & t is :y !y are s v salty4 ,:5 p want to get ! salt out ( sea wat]1 !y put ! sea wat] 9 %all[ op5 tanks & let ! wat] evaporate4 ,! salt is left beh9d4 ,,exp]im5t #ce4 ,dissolve "s salt 9 w>m wat] until no m w dissolve4 ,p\r ! cle> liquid (f into an evaporat+ di%1 be+ c>eful n to let any solid p>ticles ( ! salt g ov]4 ,ei!r set ! di% aside uncov]$1 = sev]al days1 or heat x almo/ to boil+ & let x evaporate to dryness4 ,:at is left 9 ! di%8 ,,application #bh4 ,"s girls 7 heat+ wat] = tea1 & 7 9 a hurry4 ,!y _h only an op5 /ew pan to heat ! wat] 94 ,cov] ! pan ) some?+2 y'll let all ! heat out6 ,hel5 said4 ,no1 y want z mu* heat to g ?r\gh ! wat] z possible4 ,leave ! lid (f s t ! heat c fl[ ?r\gh easily1 said ,rose4 ,! wat] w evaporate too fa/ if ! lid is (f1 & all ! heat w be us$ up 9 mak+ x evaporate2 x w take x mu* long] to get hot )\t ! lid1 ,l\ise argu$4 ,t's n "r1 ,rose answ]$4 ,boil+ wat] evaporates fa/e/ ( all4 ,we want ?is to boil1 s let x evaporate2 leave ! lid (f4 ,:at %\ld !y h done8 ,,application #bi4 ,two m5 7 ab\t to cross a des]t4 ,!y _h _! supply ( wat] 9 canvas wat] bags t leak$ j en\gh to keep ! outside ( ! bags wet4 ,naturally !y want$ to keep ! wat] z cold z possible4 ,i'm go+ to wrap my rubb] pon*o ar\nd my wat] bag & keep ! hot des]t air away f ! wat]1 said "o4 ,i'm n4 ,i'm go+ to leave m9e op5 to ! air1 ! o!r said4 ,:i* man 0 "r8 ,:y8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #aea4 ,:5 y g up high 9 an elevator1 y feel ! pressure ( ! air 9 y\r e>s4 #aeb4 ,wat] is always fl[+ into ,great ,salt ,lake2 x has no outlet2 yet x is gett+ m ne>ly empty all ! "t4 #aec4 ,a nail s9ks :ile a cork floats 9 wat]4 #aed4 ,/eep hillsides are pav$ ) cobble/ones in/ead ( asphalt4 #aee4 ,if y place "o wet glass tumbl] inside ano!r y c pull !m ap>t only ) difficulty1 & frequ5tly y break ! out] "o 9 ! attempt4 #aef4 ,sausages (t5 break _! sk9s :5 !y are be+ cook$4 #aeg4 ,a drop ( wat] spla%$ aga9/ a hot lamp *imney cracks x4 #aeh4 ,:5 y %oot an air gun1 ! air is compress$ at fir/2 !n :5 x is releas$ x spr+s out to its orig9al volume & ?r[s ! bullet ahead ( x4 #aei4 ,lea!r soles get wet ?r\gh 9 ra9y wea!r1 :ile rubb]s rema9 p]fectly dry on ! inside4 #afj4 ,:5 y want to clean a wood5 floor1 y scrub x ) a bru%4 ,,section #ai4 ,boil+ & cond5s+4 ,:at makes a geys] sp\t8 ,h[ does a /eam eng9e g8 ,once m let u imag9e we are look+ at molecules ( wat] ?r\gh our magical microscope4 ,b ?is "t suppose t ! wat] has be5 made v hot4 ,if we c\ld wat* ! molecules sma% into ea* o!r & b\nd ab\t m & m madly1 sudd5ly we %\ld see l>ge numb]s ( !m g %oot+ (f f ! re/ l rifle bullets1 & !y w\ld fly out ?r\gh ! seem+ly great spaces betwe5 ! sl[] molecules ( air4 ,?is w\ld mean t ! wat] 0 boil+ & turn+ to /eam4 ,"h are a c\ple ( exp]im5ts t w %[ y h[ mu* m room wat] takes :5 x turns to /eam ?an :ile x rema9s j wat]3 ,,exp]im5t #cf4 ,p\r a half in* ( wat] into ! bottom ( a te/ tube4 ,put a cork 9 ! te/ tube s tightly t x w n let any /eam pass x1 b n too tightly4 ,hold ! te/ tube ) a te/-tube clamp at arm's l5g? ov] a flame1 po9t+ ! cork away f y4 ,wait = results4 ,! reason ! cork flew out ( ! te/ tube is ?is3 ,/eam takes a great deal m room ?an wat] does1--_m times z mu* room2 s :5 ! wat] 9 ! te/ tube turn$ to /eam1 ! /eam _h to get out & pu%$ ! cork out ahead ( x4 ,illu/ration3 ,,fig4 #ea4 ,9 a m9ute ! cork w fly out4 ,,exp]im5t #cg4 ,p\r ab\t half an in* ( wat] into ! bottom ( a flask4 ,br+ x to a vigor\s boil ov] ! burn] & let x boil half a m9ute4 ,n[ take ! flask (f ! flame & quickly slip ! m\? ( a toy balloon ov] ! m\? ( ! flask4 ,wat* :at happ5s4 ,if ?+s g too sl[ly1 y c spe$ !m up by /rok+ ! outside ( ! flask ) a cold1 wet clo?4 ,:5 ! balloon has be5 drawn into ! flask z f> z x w g1 y c put ! flask back on ! burn] & heat ! wat] till x boils4 ,:5 ! balloon has be5 =c$ out ( ! flask aga9 & beg9s to gr[ l>ge1 take ! flask (f ! burn]4 ,d ?is be=e ! balloon explodes4 ,! reason ! balloon 0 drawn into ! flask 0 t ! /eam 9 ! flask turn$ back to wat] z x cool$1 & took v mu* less space4 ,?is left a vacuum or empty space 9 ! flask4 ,:at pu%$ ! balloon into ! empty space8 ,illu/ration3 ,,fig4 #eb4 ,a toy balloon has be5 slipp$ ov] ! m\? ( a flask t is fill$ ) /eam4 ,illu/ration3 ,,fig4 #ec4 ,z ! /eam cond5ses & leaves a vacuum1 ! air pressure =ces ! balloon into ! flask4 ,,h[ ,,/eam ,,makes ,,an ,,eng9e ,,g4 ,! =ce ( /eam is entirely due to ! fact t /eam takes s mu* m room ?an ! wat] f :i* x is made4 ,a locomotive pulls tra9s across cont95ts by us+ ?is =ce1 & by ! same =ce a %ip c>ries ?\s&s ( tons ( freight across ! ocean4 ,! eng9es ( ! locomotive & ! %ip are work$ by ! pu% ( /eam4 ,a fire is built "u a boil]4 ,! wat] is boil$2 ! /eam is %ut 92 ! only way ! /eam c get out is by pu%+ ! pi/on ahead ( x2 ! pi/on is atta*$ to ma*9]y t makes ! locomotive or %ip move4 ,,"o ,,!ory ,,ab\t ,,! ,,cause ,,( ,,volcanoes4 ,! wat] t s9ks deep d[n into "s ( ! hot p>ts ( ! e>? turns to /eam1 takes up m room1 & =ces ! wat] above x out z a geys]4 ,x is ?\ght by "s sci5ti/s t volcanoes may be />t$ by ! wat] 9 ! ocean seep+ d[n ?r\gh cracks to hot int]ior p>ts ( ! _w :]e ev5 ! /one is melt$2 !n ! wat]1 turn+ to /eam1 pu%es its way up to ! surface1 =c+ du/ & /one ahead ( x1 & mak+ a passage up = ! melt$ /one1 or lava4 ,! p]sons :o hold ?is view call att5tion to ! fact t volcanoes are always 9 or ne> ! sea4 ,if ?is is ! true explanation ( volcanoes1 !n we %\ld h no volcanoes if /eam did n take m room ?an does ! wat] f :i* x comes4 ,"h is a v practical fact ab\t boil+ wat] t _m p d n "k2 & _! gas bills w\ld be mu* small] if !y knew x4 ,try ?is exp]im5t3 ,illu/ration3 ,,fig4 #ed4 ,w boil+ wat] get hott] if y make x boil h>d]8 ,,exp]im5t #ch4 ,heat "s wat] to boil+4 ,put ! boil+-po9t !rmomet] into ! wat] 7! !rmomet] graduat$ to #aaj ,c5tigrade & #bbj ,fahr5heit71 & note ! temp]ature ( ! boil+ wat]4 ,turn up ! gas & make ! wat] boil z viol5tly z possible4 ,read ! !rmomet]4 ,does ! wat] become appreciably hott] ov] ! v hot fire ?an x does ov] ! l[ fire1 if x is boil+ 9 bo? cases8 ,b 9 :i* case is m /eam giv5 (f8 ,w a v hot fire make ! wat] boil away m rapidly ?an a l[ fire8 ,:5 y are cook+ potatoes1 are y try+ to keep !m v hot or are y try+ to boil ! wat] away f !m8 ,:i* are y try+ to d 9 mak+ c&y1 to keep ! sug> v hot or to boil ! wat] away f x8 ,all ! extra heat y put into boil+ wat] goes t[>d *ang+ ! wat] into /eam2 x _c raise ! wat]'s temp]ature1 because at ! mom5t :5 wat] gets above ! boil+ po9t x ceases to be wat] & becomes /eam4 ,?is /eam takes up mu* m room ?an ! wat] did1 s x passes (f into ! air4 ,y c tell :5 a teakettle boils by wat*+ ! sp\t to see :5 ! /eam#c p\rs =? f x 9 a /rong1 /eady /ream4 ,if ! /eam took no m room ?an ! wat]1 x c\ld /ay 9 ! kettle z easily z ! wat]4 ,footnote #c3 ,:at y see is really n ! /eam1 b ! vapor =m$ z ! /eam cond5ses 9 ! cool room4 ,! /eam itself is invisible1 z y c tell by look+ at ! m\? ( ! sp\t ( a kettle ( boil+ wat]4 ,y w see a cle> space be=e ! :ite vapor beg9s4 ,! cle> space is /eam4 ,,di/ill+4 ,:5 liquids are mix$ toge!r & dissolv$ 9 ea* o!r1 x looks z if x w\ld be impossible to take !m ap>t4 ,b x isn't4 ,!y c usually be sep>at$ almo/ p]fectly by simply boil+ !m & collect+ _! vapor4 ,= diff]5t sub/ances boil at diff]5t temp]atures j z !y melt at diff]5t temp]atures4 ,liquid air w boil on a cake ( ice2 x takes ! int5se heat ( ! electric furnace to boil melt$ iron4 ,alcohol boils at a l[] temp]ature ?an wat]2 gasol9e boils at a l[] temp]ature ?an k]os5e4 ,& p make a great deal ( practical use ( ^! facts :5 !y wi% to sep>ate sub/ances :i* h diff]5t boil+ temp]atures4 ,!y call ?is di/ill+4 ,y c d "s di/ill+ y\rself & sep>ate a mixture ( alcohol & wat] 9 ! foll[+ mann]3 ,,exp]im5t #ci4 ,fir/1 p\r a little alcohol into a cup--a few drops is en\gh--& t\* a light$ mat* to x4 ,w x burn8 ,n[ mix two teaspoonfuls ( alcohol ) ab\t half a cup ( wat] & en\gh blue+ to color ! mixture4 ,p\r a few drops ( ?is mixture into ! cup & try to light x4 ,w x burn8 ,n[ p\r ?is mixture into a flask4 ,pass ! end ( ! long b5t glass rod 7! worm7 ?r\gh a "o-hole rubb] /opp] t w fit ! flask 7,fig4 #ee74 ,put ! flask on a r+ /& &1 hold+ x /eady1 fa/5 ! neck ( ! flask ) a clamp t is atta*$ to ! /&4 ,put ! /opp] ) ! worm atta*$ into ! flask1 & support ! worm ) ano!r clamp4 ,put a dry cup or beak] "u ! l[] end ( ! worm4 ,set a light$ burn] "u ! flask4 ,:5 ! mixture 9 ! flask beg9s to boil1 turn ! flame d[n s t ! liquid w j b>ely boil2 if x boils viol5tly1 "p ( ! liquid spla%es up into ! l[] end ( ! worm4 ,z ! vapor rises f ! mixture & goes into ! worm1 x cools & cond5ses4 ,:5 sev]al drops h gone d[n into ! cup1 try light+ !m4 ,:at is x t has boil$ & !n cond5s$3 ! wat]1 ! alcohol1 or ! blue+8 ,or is x a mixture ( !m8 ,illu/ration3 ,,fig4 #ee4 ,by di/illation cle> alcohol c be sep>at$ f ! wat] & r$ ink ) :i* x 0 mix$4 ,alcohol is really made 9 ?is way1 only x is already mix$ 9 ! wat] 9 :i* ! gra9s f]m5t$ & f :i* p !n di/il x4 ,gasol9e & k]os5e are di/ill$ f petroleum2 !re is a :ole s]ies ( sub/ances t come f ! crude oil1 "o aft] ! o!r1 accord+ to _! boil+ po9ts1 & :at is left is ! f\ndation = a numb] ( products1 includ+ p>aff9e & vasel9e4 ,,exp]im5t #dj4 ,put "s dry1 fus$ calcium *lorid on a sauc] & set x on ! plate ( ! air pump4 ,?is is to absorb ! moi/ure :5 y d ! exp]im5t4 7,?is calcium *lorid is n ! same z ! *lorid ( lime :i* y buy = blea*+ or dis9fect+47 ,fill a flask or beak] half full ( wat] & br+ x to a boil ov] a ,buns5 burn]4 ,quickly set ! flask on ! plate ( ! air pump4 ,! wat] w /op boil+1 ( c\rse4 ,cov] ! flask & ! sauc] ( calcium *lorid ) ! bell j> imm$iately1 & pump ! air out ( ! j>4 ,wat* ! wat]4 ,! wat] beg9s to boil aga9 because wat] w boil at a l[] temp]ature :5 !re is less air pressure on its surface4 ,s al?\gh ! wat] is too cool to boil 9 ! op5 air1 x is /ill hot en\gh to boil :5 ! air pressure is p>tially remov$4 ,x is because ( ?is t milk is evaporat$ 9 a vacuum = cann+2 x is n necess>y to make x s hot t x w be greatly *ang$ by ! heat1 if ! boil+ is done 9 a vacuum4 ,on a high m\nta9 ! slight air pressure lets ! wat] boil at s l[ a temp]ature t x nev] becomes hot en\gh to cook food4 ,,application #cj4 ,two college /ud5ts 7 %ort ( money & _h to economize greatly4 ,!y got an alcohol lamp to use 9 cook+ _! own breakfa/s4 ,!y plann$ to boil _! eggs4 ,let's boil ! wat] g5tly1 us+ a l[ flame1 "o said2 we'll save alcohol4 ,x w\ld be bett] to boil ! eggs fa/ & get !m done quickly1 s t we c\ld put ! /ove out altoge!r1 ! o!r repli$4 ,:i* 0 "r8 ,,application #ca4 ,two girls 7 mak+ c&y4 ,!y put a little too mu* wat] into x4 ,let u boil ! c&y h>d s t x w c&y m quickly1 said "o4 ,:y1 y wa/eful girl1 said ! o!r4 ,x _c get any hott] ?an ! boil+ po9t anyh[1 s y c't cook x any fa/]4 ,:y wa/e gas8 ,:i* girl 0 "r8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #afa4 ,w>m air rises4 #afb4 ,! lid ( a teakettle rattles4 #afc4 ,heat+ wat] makes a /eam eng9e g4 #afd4 ,:5 an automobile ) good spr+s & )\t %ock absorb]s goes ov] a rut1 ! pass5g]s d n get a jolt1 b imm$iately aft]w>d b\nce up into ! air4 #afe4 ,comets sw+ ar\nd close to ! sun1 !n (f aga9 into space2 h[ d !y get away f ! sun8 #aff4 ,:5 y wi% to p\r cann$ milk out1 y ne$ two holes 9 ! c to make x fl[ ev5ly4 #afg4 ,liquid air *anges to ord9>y air :5 x becomes ev5 z w>m z a cake ( ice4 #afh4 ,skid *a9s t5d to keep automobiles f skidd+ on wet pavem5t4 #afi4 ,a w>m iron & a blott] w take c&le grease out ( y\r clo!s4 #agj4 ,c&ies l fudge & n\gat become h>d & dry :5 left /&+ sev]al days op5 to ! air4 ,,section #bj4 ,conduction ( heat & convection4 ,:y does a fea!r com=t] keep y s w>m8 ,:5 y heat "o end ( a nail1 h[ does ! heat get ?r\gh to ! o!r end8 ,h[ does a /ove make ! :ole room w>m8 ,"h is a way to make heat run a race4 ,see :e!r ! heat t goes ?r\gh an iron rod w beat ! heat t goes ?r\gh a glass rod1 or ! o!r way r\nd3 ,illu/ration3 ,,fig4 #ef4 ,! metal balls are fa/5$ to ! iron & glass rods ) drops ( wax4 ,,exp]im5t #da4 ,take a solid glass rod & a solid iron rod1 ea* ab\t a qu>t] in* 9 diamet] & ab\t #f in*es long4 ,) seal+ wax or c&le grease /ick ?ree ball be>+s or pieces ( lead1 all ! same size1 to ea* rod1 ab\t an in* ap>t1 beg9n+ #b in*es f ! end4 ,hold ! rods side by side ) _! ends 9 a flame1 & wat* ! balls fall (f z ! heat comes along ?r\gh ! rods4 ,! heat t fir/ melts (f ! balls beats4 ,illu/ration3 ,,fig4 #eg4 ,does ! heat travel fa/] ?r\gh ! iron or ?r\gh ! glass8 ,:at really happ5s d[n among ! molecules :5 ! heat travels along ! rods is t ! molecules ne> ! flame are made to move m quickly2 !y joggle _! neighbors & make !m move fa/]2 ^! joggle ! ones next to !m1 & s on d[n ! l9e4 ,heat t travels ?r\gh ?+s 9 ?is way is call$ conduct$ heat4 ,any?+ l iron1 t lets ! heat travel ?r\gh x quickly1 is call$ a good conductor ( heat4 ,any?+ l glass1 t all[s ! heat to travel ?r\gh x only ) difficulty1 is call$ a poor conductor ( heat1 or an insulator ( heat4 ,a silv] spoon us$ = /irr+ any?+ t is cook+ gets s hot all ! way up ! h&le t y c h>dly hold x1 :ile ! h&le ( a wood5 spoon nev] gets hot4 ,pancake turn]s usually h wood5 h&les4 ,metals are good conductors ( heat2 wood is a poor conductor4 ,an ev5 m obvi\s example ( ! conduct+ ( heat is se5 9 a /ove lid2 y\r fire is "u x1 yet ! top gets s hot t y c cook on x4 ,:5 any?+ feels hot to ! t\*1 x is because heat is be+ conduct$ to & ?r\gh y\r sk9 to ! s5sitive little n]ve ends j inside4 ,b :5 any?+ feels cold1 x is because heat is be+ conduct$ away f y\r sk9 into ! cold object4 ,,air ,,c>ries ,,heat ,,by ,,convection4 ,"o ( ! poore/ conductors ( heat is air2 t is1 "o p>ticle ( air c h>dly give any ( its heat to ! next p>ticle4 ,b p>ticles ( air move ar\nd v easily & c>ry _! heat ) !m2 & !y c give ! heat !y c>ry ) !m to any solid ?+ !y bump into4 ,s :5 air c move ar\nd1 ! "p t is next to ! /ove1 = in/ance1 becomes hot2 ?is hot air is pu%$ up & away by cold air1 & c>ries its heat ) x4 ,:5 x comes ov] to y 9 ano!r "p ( ! room1 "s ( its heat is conduct$ to y\r body4 ,:5 air curr5ts--or wat] curr5ts1 :i* "w ! same way--c>ry heat f "o place to ano!r l ?is1 we say t ! heat has travel$ by convection4 ,illu/ration3 ,,fig4 #eh4 ,convection curr5ts c>ry+ ! heat ( ! /ove ab\t ! room4 ,s9ce heat is s (t5 c>ri$ to u by convection1--by w>m w9ds1 w>m air f ! /ove1 w>m ocean curr5ts1 etc41--x seems z if air mu/ be a good conductor ( heat4 ,b if y %ut ! air up into _m t9y comp>tm5ts1 z a bird's fea!rs d1 or z ! hair on an animal's back does1 s t x _c circulate1 ! passage ( heat is almo/ completely /opp$4 ,:5 y use a t[el or napk9 to lift some?+ hot1 x is n s mu* ! fib]s ( cotton :i* keep ! heat f y\r h&2 x is pr9cipally ! v small pockets ( air betwe5 ! ?reads & ev5 betwe5 ! fib]s ( ! ?reads4 ,,cold ,,! ,,abs5ce ,,( ,,heat4 ,cold is m]ely ! abs5ce ( heat2 s if y keep ! heat f escap+ f any?+ w>m1 x _c become cold2 :ile if y keep ! heat f rea*+ a cold ?+ x _c become w>m4 ,a blanket is j z good = keep+ ice f melt+1 by %utt+ ! heat out1 z x is = keep+ y w>m1 by hold+ heat 94 ,,application #cb4 ,expla9 :y ice is pack$ 9 /raw or sawdu/2 :y a sweat] keeps y w>m4 ,select f ! foll[+ li/ ! good conductors ( heat f ! poor conductors 7insulators73 glass1 silv]1 iron1 wood1 /raw1 excelsior1 copp]1 asbe/os1 /eel1 nickel1 clo?1 lea!r4 ,illu/ration3 ,,fig4 #ei4 ,diagram ( a hot-wat] heat]4 ,:at makes ! wat] circulate8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #aga4 ,if ! axle ( a :eel is n greas$1 x swells until x /icks fa/ 9 ! hub2 ?is is a hot box4 #agb4 ,:5 y h put liquid %oe poli% on y\r %oes1 y\r feet become cold z x dries4 #agc4 ,! "p ( an ice-cream freez] :i* holds ! cream is usually made ( metal1 :ile t :i* goes outside & conta9s ! ice & salt is usually made ( wood4 #agd4 ,! /eam 9 a /eam radiator rises f a boil] 9 ! basem5t to ! upp] floors4 #age4 ,:5 y ?r[ a ball1 x keeps go+ = a :ile aft] x leaves y\r h&4 #agf4 ,clo!s keep y w>m1 especially wool5 clo!s4 #agg4 ,! ,lean+ ,t[] ( ,pisa does n fall ov]4 #agh4 ,x is almo/ impossible to climb a greas$ pole4 #agi4 ,heat goes up a pok] t is held 9 a fire4 #ahj4 ,a *ild c make a bicycle g rapidly )\t mak+ 8 feet g any fa/] ?an if he 7 walk+4 ,,*apt] ,,five ,,radiant ,,heat ,,& ,,light ,,section #ba4 ,h[ heat gets "h f ! sun2 :y ?+s gl[ :5 !y become v hot4 ,if we 7 to g back to our imag9>y swit*bo>d we %\ld f9d a swit*1 betwe5 ! heat & ! light swit*es1 label$ ,,radiation4 ,suppose we turn x (f3 ,in/antly ! :ole _w becomes pit* d>k2 s does ! sky4 ,we _c see ! sun or a />2 no electric lights %9e2 & al?\gh we c light a mat*1 x gives no light4 ,! air above ! burn+ mat* is hot1 & we c burn our f+]s 9 ! invisible flame1 b we c see no?+ :atev]4 ,yet ! _w does n get cold4 ,if we leave ! swit* (f = ye>s1 :ile ! e>? rema9s 9 d>kness & we all live l bl9d p1 x nev] gets cold4 ,w9t] & summ] are alike1 day & night are j ! same4 ,gradually1 aft] _m ages1 ! ice & sn[ 9 ! nor? & 9 ! f> s\? beg9 to melt z ! w>m? f ! re/ ( ! _w is conduct$ to ! pol> regions4 ,& ! heat f ! int]ior ( ! e>? makes all ! p>ts ( ! e>?'s surface w>m]4 ,w9ds almo/ /op bl[+4 ,ocean curr5ts /op fl[+4 ,! l& receives less ra9fall1 until f9ally ev]y?+ turns to a des]t2 almo/ ! only ra9 is on ! ocean4 ,animals die ev5 be=e ! riv]s dry up1 = ! fle% eat]s are n able to see _! prey1 & s9ce1 )\t light1 all gre5 ?+s die1 ! animals t live on plants soon />ve4 ,m5 h to le>n to live on mu%rooms1 :i* gr[ 9 ! d>k4 ,! _w is plung$ into an et]nal w>m1 pit*-black night4 ,illu/ration3 ,,fig4 #fj4 ,x is by radiation t we get all our heat & light f ! sun4 ,turn+ (f ! radiation w\ld cause all ^! ?+s to happ51 because x is by radiation t we get all our heat f ! sun & all our light f any s\rce4 ,& x is by radiation t ! e>? loses heat into space 9 ! night & loses /ill m heat into space dur+ ! w9t]4 ,we d n get our heat f ! sun by conduction2 we _c1 because !re is no?+ betwe5 u & ! sun to conduct x4 ,! e>?'s air1 9 am\nts ?ick en\gh to c\nt1 goes up only a hundr$ miles or s4 ,x is really j a ?9 sort ( blanket surr\nd+ ! e>?4 ,! sun is #ic1jjj1jjj miles away4 ,betwe5 u & ! sun !re is empty space4 ,!re are no molecules to speak ( 9 t :ole va/ di/ance4 ,s if heat travel$ only by conduction1--t is1 if radiation /opp$1--we %\ld be s completely %ut (f f ! sun t we %\ld n "k !re 0 su* a ?+4 ,b ev5 if we fill$ ! space betwe5 u & ! sun ) copp] or silv]1 :i* are ab\t ! be/ conductors ( heat 9 ! _w1 x w\ld take ! heat f ! sun ye>s & ye>s to be conduct$ d[n to u4 ,yet we "k t ! sun's heat really gets to u 9 a few m9utes4 ,?is is because heat c travel 9 a v mu* quick] way ?an by conduction4 ,x radiates ?r\gh space1 j z light does4 ,& x c come ! :ole #ic1jjj1jjj miles f ! sun 9 ab\t #h m9utes4 ,?is is s fa/ t if x 7 go+ ar\nd ! _w in/ead ( com+ f ! sun1 x w\ld g ar\nd #g-a_/b times be=e y c\ld say ,jack ,rob9son1--really1 because x takes y at lea/ "o second to say ,jack ,rob9son4 ,we are n absolutely sure h[ heat gets "h s fa/4 ,b :at mo/ sci5ti/s ?9k n[adays is t !re is a sort ( invisible rigid /uff1 n made ( molecules or ( any?+ b j itself1 call$ e!r4 7,?is e!r1 if !re really is su* a ?+1 is n relat$ at all to ! e!r t doctors use 9 putt+ p to sleep4 ,x j happ5s to h ! same "n47 ,! e!r is suppos$ to fill all space1 ev5 ! t9y spaces betwe5 molecules4 ,! fa/ mov+ p>ticles ( ! sun joggle ! e!r up !re1 & make ripples t spread out swiftly all ?r\gh space4 ,:5 ^? ripples /rike our e>?1 !y make ! molecules ( e>? joggle1 & t is heat4 ,! ripples t spread out f ! sun are call$ e!r waves4 ,b ! important & practical fact to "k is t !re is a k9d ( heat1 call$ radiant heat1 t c pass ?r\gh empty space ) lightn+-l quickness4 ,& :5 ?is radiant heat /rikes ?+s1 x is p>tly absorb$ & *ang$ to ! usual k9d ( heat4 ,?is radiant heat is closely relat$ to light4 ,z a matt] ( fact1 light is only ! special k9d ( e!r waves t affect our eyes4 ,radiant heat is invisible4 ,! e!r waves t are visible we call light4 ,9 t]ms ( e!r waves1 ! only diff]5ce betwe5 light & radiant heat is t ! ripples 9 light are %ort]4 ,s x is no wond] t :5 we get a piece ( iron hot en\gh1 x beg9s to give (f light2 & we say x is r$ hot4 ,:at happ5s to ! e!r is ?is3 ,z ! molecules ( iron g fa/] & fa/] 7t is1 z ! iron gets hott] & hott]71 !y make ! ripples 9 ! e!r move m frequ5tly until !y get %ort en\gh to be light in/ead ( radiant heat4 ,objects give (f radiant heat )\t %[+ x at all2 ! w>m? t y feel j bel[ a hot flatiron is ma9ly radiant heat4 ,:5 any?+ becomes hot en\gh to gl[1 we say x is inc&esc5t4 ,t is :y electric lamps are call$ inc&esc5t lamps4 ,! f9e wires--call$ ! filam5t--9 ! lamp get s hot :5 ! electricity fl[s ?r\gh !m t !y gl[ or become inc&esc5t1 ?r[+ (f light & radiant heat4 ,x is ! absorb+ ( ! radiant heat by y\r h& t makes y feel ! heat ! in/ant y turn an electric lamp on4 ,try ?is exp]im5t3 ,,exp]im5t #db4 ,turn on an inc&esc5t lamp t is cold4 ,feel x ) y\r h& a second1 !n turn x (f at once4 ,is ! glass hot8 7,! lamp y use %\ld be an ord9>y #be1 #dj1 or #fj watt vacuum lamp47 ,! radiant heat f ! inc&esc5t filam5t 9 ! lamp pass$ "r out ?r\gh ! vacuum ( ! lamp1 & mu* ( x w5t on ?r\gh ! glass to y\r h&4 ,y already "k :at a poor conductor ( heat glass is2 yet x lets a great deal ( radiant heat pass ?r\gh x1 j z x does light4 ,z soon z ! lamp /ops gl[+1 ! heat /ops com+2 ! glass is n made hot & y no long] feel any heat4 ,9 "o way ! electric filam5t %9+ ?r\gh a vacuum is exactly l ! sun %9+ ?r\gh empty space3 ! heat f bo? comes to u by radiation4 ,if a lamp gl[s = a long "t1 h[ev]1 ! glass really does become hot4 ,t is p>tly because !re is n a p]fect vacuum )9 x 7!re is a little gas inside t c>ries ! heat to ! glass by convection71 & x is p>tly because ! glass does n let q all ( ! radiant heat & light g ?r\gh x1 b absorbs "s & *anges x to ! regul> conduct$ heat4 ,"o practical use t is made ( a k ( ! diff]5ce betwe5 radiant & conduct$ heat is 9 ! manufacture ( !rmos bottles4 ,,exp]im5t #dc4 ,take a !rmos bottle ap>t4 ,exam9e x c>efully4 ,if x is ! /&>d !rmos bottle1 ) ! "n !rmos on x1 y w f9d t x is made ( two lay]s ( glass ) a vacuum betwe5 !m4 ,! vacuum keeps any conduct$ heat f gett+ out ( ! bottle or into x4 ,b1 z y "k1 radiant heat c fla% "r ?r\gh a vacuum4 ,s to keep x f do+ ?is ! glass is silv]$1 mak+ a mirror out ( x4 ,j z a mirror s5ds light back to :]e x comes f1 x s5ds practically all radiant heat back to :]e x comes f4 ,heat1 !re=e1 _c get into ! !rmos bottle or out ( x ei!r by radiation or conduction4 ,& t is :y !rmos bottles w keep ?+s v hot or ice-cold = su* a long "t4 ,fill ! !rmos bottle ) boil+ wat]1 /opp] x1 & put x aside till ! next day4 ,see :e!r ! wat] is /ill hot4 ,illu/ration3 ,,fig4 #fa4 ,h[ a !rmos bottle is made4 ,notice ! d\ble lay] ( glass 9 ! brok5 "o4 ,if we c\ld make ! vacuum p]fect1 & surr\nd all p>ts ( ! bottle1 ev5 ! m\?1 ) ! p]fect vacuum1 & if ! mirror 7 p]fect1 ?+s put into a !rmos bottle w\ld /ay boil+ hot or icy cold =ev] & ev]4 ,,:y ,,x ,,is ,,cool ,,at ,,night ,,& ,,cold ,,9 ,,w9t]4 ,x is ! radiation ( heat f ! e>? into space t makes ! e>? cool] at night & cold 9 w9t]4 ,mu* ( ! heat t ! e>? absorbs f ! sun 9 ! daytime radiates away at night4 ,& s9ce x keeps on radiat+ away until ! sun br+s u m heat ! next day1 x is cold] j be=e dawn ?an at midnight1 m heat hav+ radiat$ into space4 ,= ! same reason x is cold] 9 ,janu>y & ,febru>y ?an 9 ,decemb]4 ,x is 9 ,decemb] t ! days are %orte/ & ! sun %9es on u at ! greate/ slant1 s t we get ! lea/ heat f x2 b we /ill h left "s ( ! heat t 0 absorb$ 9 ! summ]4 ,& we keep los+ ?is heat by radiation fa/] ?an we get heat f ! sun1 until almo/ spr+4 ,,application #cc4 ,di/+ui% betwe5 radiant & conduct$ heat 9 ea* ( ! foll[+ examples3 7a7 ,! sun w>ms a room ?r\gh ! w9d[4 7b7 ,a room is cool] ) ! %ades d[n ?an up1 :5 ! sun %9es on ! w9d[4 7c7 ,b ev5 ) ! %ades d[n a room on ! sunny side ( ! h\se is w>m] ?an a room on ! %ady side4 7d7 ,:5 a mirror is fac+ ! sun1 ! back gets hot4 7e7 ,if y put y\r h& 9 front ( a mirror held 9 ! sun1 ! mirror reflects heat to y\r h&4 7f7 ,if y put a plate on a /eam radiator1 ! top ( ! plate gradually becomes hot4 7g7 ,if any?+ v hot or cold t\*es a gold or amalgam fill+ ( a s5sitive too?1 y feel x decid$ly4 7h7 ,! h&le ( y\r s\p spoon becomes hot :5 ! b[l ( x is 9 ! hot s\p4 7i7 ,! moon is n[ v cold1 al?\gh x probably 0 once v hot4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #aha4 ,trees b5d 9 ! w9d1 !n /raight5 up aga94 ,:y d !y /raight5 up8 #ahb4 ,a clo? saturat$ ) k]os5e & plac$ 9 ! bottom ( a clock w oil ! clockworks above x4 #ahc4 ,9 cold wea!r ! doorknob inside ! front door is cold4 #ahd4 ,x is cool 9 ! %ade4 #ahe4 ,clo!s get hot :5 y iron !m4 #ahf4 ,potatoes fri$ 9 deep fat cook m quickly ?an ^? boil$ 9 wat]4 #ahg4 ,if y hold y\r h& ne> a vacuum electric lamp globe t is gl[+1 "s ( ! heat w g out to y\r h& at once4 #ahh4 ,rubb+ silv] ) f9e p[d] poli%es x4 #ahi4 ,a mosquito c suck y\r blood4 #aij4 ,a hot-wat] tank becomes hot at ! top fir/1 !n gradually heats d[nw>d4 ,:5 y light ! gas "u an ord9>y hot-wat] heat]1 ! hot wat] circulates to ! top ( ! boil]1 :ile ! cold wat] f ! boil] pu%es into ! bottom "p ( ! heat]1 z %[n 9 ,figure #ei4 ,:at causes ?is circulation8 ,,section #bb4 ,reflection4 ,h[ is x t y c see y\rself 9 a mirror8 ,:at makes a r+ ar\nd ! moon8 ,:y c we see cl\ds & n ! air8 ,:y is a pair ( new %oes or any?+ smoo? usually %9y8 ,if we turn (f a swit* label$ ,,reflection ,,( ,,light on our imag9>y swit*bo>d1 we ?9k at fir/ t we h accid5tally turn$ (f ,,radiation aga91 = once m ev]y?+ in/antly becomes d>k ar\nd u4 ,we _c see our h&s 9 front ( our faces4 ,al?\gh x is ! middle ( ! day1 ! sky is jet black4 ,b ?is "t we see bright />s %9+ 9 x4 ,& among !m is ! sun1 %9+ z brightly z ev] & dazzl+ our eyes :5 we look at x4 ,b its light does no good4 ,:5 we look d[n f ! sky t[>d ! e>?1 ev]y?+ is s black t we %\ld ?9k we 7 bl9d if we _h n j se5 ! />s & sun4 ,grop+ our way along to an electric lamp1 we turn x on4 ,x %9es brightly1 b x does n make any?+ ar\nd x light2 ev]y?+ /ays absolutely invisible4 ,x is z if all ?+s 9 ! _w except ! lights _h put on "s sort ( magic invisible caps4 ,we c /rike a mat* & see its flame4 ,we c see a fire on ! he>?4 ,we may feel ar\nd = ! invisible pok]1 & :5 we f9d x1 we may put x 9 ! fire4 ,:5 x becomes hot en\gh1 x w gl[ r$ & become visible4 ,we c make a mat* head gl[ by rubb+ x on a wet f+]4 ,we c ev5 see a firefly1 if "o comes ar\nd4 ,b only ^? ?+s :i* are gl[+ ( !mselves1 l flames1 & r$-hot pok]s1 & fireflies1 w be visible4 ,! reason :y practically ev]y?+ w\ld be invisible if !re 7 no reflection ( light is ?is3 ,:5 y look at any?+1 z a man1 = in/ance1 :at y really see is ! light t hits him & b\nces back 7reflects7 into y\r eyes4 ,suppose y g into a d>k room & turn on an electric light4 ,in/antly ripples ( light fla% out f ! lamp 9 e direction4 ,z soon z !y /rike ! object y are look+ at1 !y reflect 7b\nce back7 f x to y\r eyes4 ,:5 light /rikes y\r eyes1 y see4 ,( c\rse1 :5 y look at an electric lamp1 or a />1 or ! sun1 or any?+ t is inc&esc5t 7s hot t x %9es by its own light71 y c see x1 :e!r reflection exi/s or n4 ,b mo/ ?+s y look at d n %9e by _! own light4 ,?is book t y are read+ simply reflects ! light 9 ! room to y\r eyes2 x w\ld n give any light 9 a d>k room4 ,! pap] reflects a good deal ( light t /rikes x1 s x looks v light2 ! pr9t reflects practically none ( ! light t /rikes x1 s x looks d>k1 or black1 j z a keyhole looks black because x does n reflect any light to y\r eyes4 ,b )\t reflection1 ! book w\ld be entirely invisible4 ,! only k9d ( pr9t y c\ld read if !re 7 no reflection w\ld be ! electric signs made out ( inc&esc5t lamps arrang$ to =m lett]s4 ,,:at ,,! ,,r+ ,,ar\nd ,,! ,,moon ,,is2 ,,:at ,,sunbeams ,,are4 ,! reason y sometimes see a r+ ar\nd ! moon is t "s ( ! moonlight reflects f t9y droplets ( wat] 9 ! air1 mak+ !m visible4 ,9 ! same way1 ! du/ 9 ! air ( a room becomes visible :5 ! sun %9es ?r\gh x & is reflect$ by ea* speck ( du/2 we call x a sunbeam4 ,b we are n really look+ directly at ! sunlight2 we are see+ ! "p ( ! sunlight t is reflect$ by ! du/ specks4 ,h y ev] notic$ t :5 y /& a little to "o side ( a mirror :]e y _c see y\r own image 9 x1 y c sometimes see t ( ano!r p]son cle>ly1 :ile he _c see 8 own image b c see y\rs8 ,x is easy to und]/& ?is by comp>+ ! reflection ( ! light f y\r face to 8 eye & f 8 face to y\r eye1 to ! b\nc+ ( a ball f "o p]son to ano!r4 ,suppose y & a fri5d are /&+ a little way ap>t on s&y gr\nd :]e y _c b\nce a ball1 b t betwe5 y !re is a plank4 ,if ea* ( y is /&+ well away f ! plank1 nei!r "o ( y c possibly b\nce ! ball on x 9 su* a way t he c cat* x himself4 ,yet y c easily b\nce x to y\r fri5d & he c b\nce x to y4 ,illu/ration3 ,,fig4 #fb4 ,! ball b\nces f "o boy to ! o!r1 b x does n return to ! "o :o ?rew x4 ,! mirror is l t plank2 x is some?+ t w reflect 7b\nce7 ! light directly4 ,! light f y\r face goes into ! mirror1 j z y may ?r[ ! ball aga9/ ! plank1 & ! light is reflect$ to y\r fri5d j z ! ball is b\nc$ to him2 s he sees y\r image 9 ! mirror4 ,if he c see y1 y c see him1 j z :5 y b\nce ! ball to him he c b\nce x to y4 ,b y may be unable to see y\rself1 j z y may be unable to b\nce ! ball on ! plank s t y y\rself c cat* x4 ,9 o!r words1 :5 light /rikes aga9/ some?+ x b\nces away1 j z a rubb] ball b\nces f a smoo? surface4 ,if y ?r[ a ball /raight d[n1 x comes /raight up2 if light %9es /raight d[n on a flat1 smoo? surface1 x reflects /raight up4 ,if y ?r[ a ball d[n at a slant1 x b\nces up at ! same slant 9 ! opposite direction2 if light /rikes a smoo? surface at a slant1 x reflects at ! same slant 9 ! opposite direction4 ,illu/ration3 ,,fig4 #fc4 ,9 ! same way1 ! light b\nces 7reflects7 f "o boy to ! o!r4 ,x does n return to ! po9t f :i* x />t$ & nei!r boy c see himself4 ,b to reflect light directly & to give a cle> image1 ! surface ! light /rikes mu/ be extremely smoo?1 j z a t5nis c\rt mu/ be fairly smoo? to make a t5nis ball reb\nd accurately4 ,any surface t is smoo? en\gh w act l a mirror1 al?\gh naturally1 if x lets mo/ ( ! light g ?r\gh1 x w n reflect z well z if x s5ds all ! light back4 ,a pane ( glass is v smoo?1 & y c see y\rself 9 x1 especially if !re is n mu* light com+ ?r\gh ! glass f ! o!r side to mix up ) y\r reflection4 ,b if ! pane ( glass is silv]$ s t no light c get ?r\gh1 y h a real mirror2 mo/ ( ! light t leaves y\r face is reflect$ to y\r eyes aga94 ,,:y ,,smoo? ,,or ,,wet ,,?+s ,,are ,,%9y4 ,:5 a surface is v smoo?1 we say x is %9y or glossy4 ,ev5 black %oes1 if !y are poli%$1 become smoo? en\gh to reflect mu* ( ! light t /rikes !m2 ( c\rse ! p>ts :]e ! light is be+ reflect$ d n look black b :ite1 z any "o :o has tri$ to pa9t or draw a picture ( poli%$ %oes kn[s4 ,any?+ wet is likely to be %9y1 because ! surface ( wat] is usually smoo? en\gh to reflect light r directly4 ,if a surface is unev51 l a pool ) ripples on x1 ! light reflects unev5ly1 & y see a di/ort$ image2 y\r face seems to be rippl+ & mov+ 9 ! wat]4 ,illu/ration3 ,,fig4 #fd4 ,h[ %\ld ! mirror be plac$8 ,,application #cd4 ,"s boys 7 play+ w> & 7 9 a dit* t !y call$ a tr5*4 ,!y want$ to make a simple p]iscope s t !y c\ld look out ( ! dit* at ! enemy )\t be+ 9 dang]4 ,!y _h an old /ovepipe & a mirror4 ,practically all ( !m agre$ t if ! mirror 7 fix$ 9 ! top ( ! /ovepipe & if !y look$ up ?r\gh ! bottom1 !y w\ld be able to see ov] ! side ( ! dit*4 ,b !y _h an argum5t z to h[ ! mirror %\ld be plac$4 ,ea* drew a diagram to %[ h[ he ?\ght ! mirror %\ld be arrang$1 us+ dott$ l9es to %[ h[ ! light w\ld come f ! enemy to _! eyes4 ,?ree ( ! diagrams are %[n 9 ,figure #fd4 ,! boy :o drew ! fir/ said3 ,if y want to see ! enemy1 ! mirror's got to face him4 ,!n x w reflect ! light d[n to y\r eyes4 ,! boy :o drew ! second said3 ,no1 ! light w\ld j g back to him aga94 ,! mirror mu/ slant s t ! light t /rikes x at a slant w be reflect$ to y\r eye at ! same slant4 ,h[ c\ld x get to y\r eye at all1 ! ?ird boy said1 if ! mirror didn't face y8 ,y've got to h ! mirror reflect "r d[n t[>d y\r face4 ,!n all ! light t /rikes x w come d[n to y4 ,:i* arrangem5t w\ld "w8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #aia4 ,y\r h&s d n get wet :5 y put !m into m]cury4 #aib4 ,:5 beat+ hot c&y1 we sometimes put x 9 a pan ( wat]4 #aic4 ,electric /oves frequ5tly h bright reflectors4 #aid4 ,we put ice 9 ! top ( a refrig]ator4 #aie4 ,y c jack up ! back "p ( an automobile :5 y c\ld n possibly lift x up4 #aif4 ,! sun %9es up into y\r face & sunburns y :5 y are on ! wat]4 #aig4 ,p 9 ! tropics dress l>gely 9 :ite4 #aih4 ,m5?ol rubb$ into y\r sk9 makes x feel v cold aft]w>d4 #aii4 ,we feel ! heat ( ! sun almo/ z soon z ! sun rises4 #bjj4 ,y c %oot a /one f> & h>d ) a sl+ %ot4 ,,section #bc4 ,! b5d+ ( light3 ,refraction4 ,h[ d glasses help y\r eyes8 ,on a hot day1 h[ is x t y see heat waves ris+ f ! /reet8 ,:at makes ! />s tw9kle8 ,light usually travels 9 /raight l9es4 ,if ! light f an object comes f /raight 9 front ( y1 y "k t ! object is /raight 9 front ( y4 ,b y c b5d light s t x seems to come f a diff]5t place1 ?us mak+ ?+s seem to be :]e !y are n4 ,,exp]im5t #dd4 ,hold a triangul> glass prism v]tically 7/raight up & d[n7 9 front ( "o eye1 clos+ ! o!r eye4 ,look ?r\gh ! prism1 turn+ x or y\r head ar\nd until y see a *air ?r\gh x4 ,wat* only ! *air ?r\gh ! prism4 ,:5 y are sure y "k j :]e x is1 try to sit d[n 9 x4 ,n[ look = a p5cil or a piece ( *alk ?r\gh ! prism1 9 ! same way4 ,:5 y ?9k y "k :]e x is1 try to pick x up4 ,! reason ! *alk & *air seem to be :]e !y are n is t ! prism b5ds ! light t comes f !m & makes ! light seem to come f some:]e else4 ,z y already "k1 :5 y look at a *air y see ! light t reflects f x4 ,y judge :]e ! *air is by ! direction f :i* ! light is com+ :5 x rea*es y\r eye4 ,b if ! light is b5t on its way1 s t x comes to y\r eye z x ord9>ily comes f an object (f to "o side1 naturally y ?9k ! ?+ y are look+ at is (f to "o side4 ,maybe ! diagram 7,fig4 #fe7 w make ?is cle>]4 ,illu/ration3 ,,fig4 #fe4 ,9 pass+ ?r\gh ! prism ! light is b5t s t an object at b appe>s to be at c4 ,"h 9 a is an object ! same height z ! eye4 ,! light comes /raight to ! eye1 & "o kn[s t ! object is level ) ! eye4 ,9 b ! object is 9 ! same position z 9 a1 b ! prism b5ds ! light s t x /rikes ! eye ) an upw>d slant4 ,s ! p]son ?9ks ! object is bel[ ! eye at c4 ,"h is ano!r exp]im5t ) b5d+ light3 ,,exp]im5t #de4 ,fill a *9a cup ) wat]4 ,put a p5cil 9 x1 lett+ ! p5cil re/ at a slant f left to "r4 ,l[] y\r head until x is almo/ level ) ! surface ( ! wat]4 ,h[ does ! p5cil look8 ,illu/ration3 ,,fig4 #ff4 ,! p5cil is n b5t1 b ! light t comes f x is4 ,! reason ! p5cil looks b5t is because ! light f ! "p ( x "u ! wat] is b5t :5 x passes f ! wat] into ! air on its way to y\r eye2 s ! slant at :i* x comes to y\r eye is ! same slant at :i* x ord9>ily w\ld come f a b5t p5cil4 ,,exp]im5t #df4 ,fill a glass ) wat]4 ,put ! p5cil into x 9 ! same way y put x 9 ! cup 9 ! previ\s exp]im5t1 lett+ ! p5cil slant f left to "r4 ,l[] y\r head ?is "t until x is on a level ) ! wat] 9 ! glass1 & look ?r\gh ! glass & wat] at ! p5cil4 ,notice :at happ5s :]e ! p5cil goes into ! wat]4 ,:at y see is expla9$ 9 ! same way z are ! ?+s t took place 9 ! o!r exp]im5ts 9 refraction1 or b5d+ ( light4 ,! light f ! "p ( ! p5cil above ! wat] comes /raight to y\r eye1 ( c\rse2 s y see x j z x is4 ,b ! light f ! "p ( ! p5cil 9 ! wat] is b5t :5 x comes out ( ! wat] into ! air on its way to y\r eye4 ,?is makes x come to y\r eye f a diff]5t direction & makes ! l[] "p ( ! p5cil seem to be 9 a place to "o side ( ! place :]e x really is4 ,! p5cil1 !re=e1 looks brok54 ,illu/ration3 ,,fig4 #fg4 ,! b5d+ ( ! light by ! wat] 9 ! glass causes ! p5cil to look brok54 ,:5ev] light passes fir/ ?r\gh some?+ d5se l wat] or glass1 & !n ?r\gh some?+ r>e or ?9 l air1 x is b5t "o way2 :5ev] x passes f a r>e m$ium into a d5se "o1 x is b5t ! o!r way4 ,light pass+ f a fi% to y\r eye is b5t "o way2 light pass+ f y to ! fi%'s eye is b5t ! o!r way1 b ! ma9 po9t is t x is b5t4 ,& :5 light is b5t be=e rea*+ y\r eyes x usually makes ?+s seem to be :]e !y are n4 ,if light goes ?r\gh a p]fectly smoo?1 flat pane ( glass1 x is b5t "o way :5 x goes into ! glass & back ! o!r way :5 x comes out2 s x seems to be p]fectly /raight & we see ?+s practically z !y are ?r\gh a good w9d[4 ,b if ! w9d[ glass has flaws 9 x1 s t "s p>ts are a little ?ick] ?an o!rs1 ! unev5 p>ts act l prisms & b5d ! light to "o side4 ,?is makes any?+ we look at ?r\gh a poor w9d[ seem b5t out ( %ape4 ,( c\rse ! ?+s are n b5t any m ?an y\r p5cil 9 ! wat] 0 b5t1 b !y look mis%ap5 because ! light f !m is b5t2 ! reflect$ light is all we see ( ?+s anyway4 ,illu/ration3 ,,fig4 #fh4 ,! light is b5t :5 x ent]s a w9d[ pane & is b5t aga9 9 ! opposite direction :5 x leaves x4 ,! air itself is unev5 9 a way4 ,! p>ts ( ! air t are w>m1 z y already "k1 are ?9n] & m exp&$ ?an are ! cold p>ts4 ,s light go+ f cold air into w>m or f w>m air into cold1 w be b5t4 ,& ?is is :y y see :at are call$ heat waves above a /ove or ris+ f a hot bea* or sidewalk4 ,really ^! are j waves ( hot air ris+1 & !y b5d ! light t comes ?r\gh !m s z to give ev]y?+ beh9d !m a wavy appe>ance4 ,/>s tw9kle = mu* ! same reason4 ,z ! />light comes d[n ?r\gh ! cold air & !n ?r\gh ! w>m air x is b5t1 & ! /> seems to be to "o side ( :]e x really is2 b ! air does n /& /ill1--sometimes x b5ds ! light m & sometimes less4 ,s ! /> seems to move a little back & =?4 ,& ?is is :at we call tw9kl+4 ,really x is ! b5d+ ( light4 ,,application #ce4 ,expla9 :y an unev5ness 9 y\r eye w keep y f see+ cle>ly2 h[ glasses c help ?is2 :y good mirrors are made f plate glass1 :i* is v smoo?1 in/ead ( f ! *eap] & m unev5 w9d[ glass2 :y fi%es 9 a glass tank appe> to be :]e !y are n4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bja4 ,! fire 9 ! op5 fireplace v5tilates a room well by mak+ air g up ! *imney4 #bjb4 ,a drop ( wat] gli/5s 9 ! sun4 #bjc4 ,du/ goes up to ! ceil+ & cl+s !re4 #bjd4 ,:5 y look at a p]son "u mov+ wat]1 8 face seems di/ort$4 #bje4 ,y sit 9 ! sun to dry y\r hair4 #bjf4 ,pa/e becomes h>d & unfit = use :5 left op5 to ! air4 #bjg4 ,9 laundries clo!s are p>tly dri$ by :irl+ !m 9 p]=at$ cyl9d]s4 #bjh4 ,circus balloons are fill$ by build+ a big fire "u !m4 #bji4 ,unev5ness 9 a w9d[ pane makes telephone wires se5 ?r\gh x look crook$ & b5t4 #baj4 ,y c see ! image ( a /> ev5 9 a %all[ puddle4 ,illu/ration3 ,,fig4 #fi4 ,:5 ! light f "o po9t goes ?r\gh ! l5s1 x is b5t & comes toge!r at ano!r po9t call$ ! focus4 ,,section #bd4 ,focus4 ,h[ c y take pictures ) a cam]a8 ,:at causes ! picture 9 ! cam]a to be inv]t$8 ,:y is a magnify+ glass able to set ?+s on fire :5 y let ! sun %9e ?r\gh x8 ,9 y\r eye1 "r back ( ! pupil1 !re is a flatt5$ ball1 z cle> z glass1 call$ ! l5s4 ,if ! l5s 7 left out ( y\r eye1 y nev] c\ld see any?+ except blurs ( light & %ad[4 ,if y look$ at ! sun x w\ld dazzle y practically z mu* z x does n[4 ,h[ev]1 y w\ld n see a r\nd sun1 b only a blaze ( light4 ,y c\ld tell night f day z well z any "o1 & y c\ld tell :5 y /epp$ into ! %ade4 ,if "s "o /epp$ betwe5 y & ! light1 y w\ld "k t "s "o 0 betwe5 y & ! light or t a cl\d _h pass$ ov] ! sun1--y c\ld n be q sure :i*4 ,9 %ort1 y c\ld tell all degrees ( light & d>k ap>t ne>ly z well z y c n[1 b y c\ld n see ! =m ( any?+4 ,9 ! front ( a cam]a !re is a flatt5$ glass ball call$ ! l5s4 ,if y 7 to remove x1 ! cam]a w\ld n take any pictures2 x w\ld take a blur ( light & %ade & no?+ m4 ,illu/ration3 ,,fig4 #gj4 ,! light f ea* po9t ( ! c&le flame goes out 9 all directions4 ,9 front ( a mov+-picture ma*9e !re is a l>ge l5s1 a piece ( glass r\nd$ out t[>d ! middle & ?9n] t[>d ! edges4 ,if y 7 to take t l5s (f :ile ! ma*9e 0 ?r[+ ! motion pictures on ! scre51 y w\ld h a flick] ( light & %ade1 b no picture4 ,x is ! l5s t =ms ! pictures 9 y\r eye1 on a photographic plate or film1 & on a mov+-picture scre54 ,& a l5s is usually j a piece ( glass or some?+ glassy1 r\nd$ out 9 su* a way z to make all ! spread+ light t rea*es x f "o po9t come toge!r 9 ano!r po9t1 z %[n 9 ,figure #fi4 ,z y "k1 :5 light goes out f any?+1 z f a c&le flame or an inc&esc5t lamp1 or f ! sun1 x goes 9 all directions4 ,if ! light f ! po9t ( a c&le flame goes 9 all directions1 & if ! light f ! base ( ! flame also goes 9 all directions1 ! light f ! po9t w get all mix$ up ) ! light f ! base1 z %[n 9 ,figure #gj4 ,naturally1 if ! light f ! po9t ( ! c&le flame is mix$ up ) ! light f ! base & ! beams are all crisscross1 y w n get a cle> picture ( ! flame4 ,illu/ration3 ,,fig4 #ga4 ,! read+ glass is a l5s :i* focuses ! light f ! c&le flame & =ms an image4 ,,exp]im5t #dg4 ,fa/5 a piece ( pap] aga9/ a wall & place a light$ c&le ab\t #d feet 9 front ( x4 ,look at ! pap]4 ,is !re any picture ( ! c&le flame on x8 ,n[ hold a magnify+ glass 7read+ glass7 ne> ! c&le1 betwe5 ! c&le & ! pap]1 s t ! light w %9e ?r\gh ! l5s on to ! pap]4 7,! magnify+ glass is a l5s47 ,move ! l5s sl[ly t[>d ! pap] until y get a cle> picture ( ! c&le flame4 ,is x "r side up or upside d[n8 ,! l5s has br\ght ! light f ! c&le flame to a focus2 all ! light t goes ?r\gh ! l5s f "o po9t ( ! flame has be5 br\ght toge!r at ano!r po9t 7,fig4 #gb74 ,9 ! diagram y see all ! light f ! po9t ( ! c&le flame spread+ out 9 e direction4 ,b ! "p t goes ?r\gh ! l5s is br\ght toge!r at "o po9t1 call$ ! focus4 ,( c\rse ! same ?+ happ5s to ! light f ! base ( ! c&le flame 7,fig4 #gc74 ,j z be=e1 all ! light f ! base ( ! flame is br\ght to a focus4 ,! light spreads out until x rea*es ! l5s4 ,!n ! l5s b5ds x toge!r aga9 until x comes to a po9t4 ,illu/ration3 ,,fig4 #gb4 ,! light f ! tip ( ! c&le flame is focus$ at "o po9t4 ,illu/ration3 ,,fig4 #gc4 ,& ! light f ! base ( ! flame is focus$ at ano!r po9t4 ,illu/ration3 ,,fig4 #gd4 ,! light f ! tip & base 7& f e o!r po9t7 ( ! flame is1 ( c\rse1 focus$ at ! same "t4 ,9 ?is way an image ( ! flame is =m$4 ,b ( c\rse ! light f ! base ( ! flame is focus$ at ! same "t z ! light f ! po9t2 s :at really happ5s is t :i* is illu/rat$ 9 ,figure #gd4 ,9 ?is diagram1 we h drawn unbrok5 l9es to %[ ! light f ! po9t ( ! c&le flame & dott$ l9es to %[ ! light f ! base ( ! flame4 ,?is is s t y c foll[ ! light f ea* "p & see :]e x goes4 ,comp>e ?is diagram ) ! "o :]e ! light is %[n all crisscross$ 7,fig4 #gj71 & y w see :y ! l5s makes an image1 :ile y h no image )\t x4 ,by look+ at ! la/ diagram 7,fig4 #gd7 y c also see h[ ! image happ5s to be upside d[n4 ,,exp]im5t #dh4 ,set up ! c&le & piece ( pap] z y did = ! la/ exp]im5t1 b move ! magnify+ glass back & =? betwe5 ! pap] & ! c&le4 ,notice t !re is "o place :]e ! image ( ! c&le is v cle>4 ,does ! image become cle>] or less cle> if y move ! l5s clos] to ! c&le8 if y move x f>!r f ! c&le8 ,! explanation is ?is3 ,aft] ! light comes toge!r into a po9t1 x spreads out aga9 beyond ! po9t1 z %[n 9 ,figure #ge4 ,s if y hold ! l5s 9 su* a way t ! light comes to a focus be=e x rea*es ! pap]1 ! pap] w cat* ! spread+ light & y w get a blur in/ead ( a %>p image4 ,x is z %[n 9 ,figure #gf4 ,illu/ration3 ,,fig4 #ge4 ,! light spreads out aga9 beyond ! focus4 ,illu/ration3 ,,fig4 #gf4 ,s if ! light comes to a focus be=e x rea*es ! pap]1 ! image w be blurr$4 ,on ! o!r h&1 if y hold y\r l5s 9 su* a way t ! light has n yet come to a focus :5 x rea*es ! pap]1 naturally y aga9 h a blur ( light in/ead ( a po9t1 & ! image is n %>p & def9ite 7,fig4 #gg74 ,illu/ration3 ,,fig4 #gg4 ,or if ! light rea*es ! pap] be=e x comes to a focus1 ! image w be blurr$4 ,& t is :y good cam]as h ! front "p1 9 :i* ! l5s is set1 adju/able2 y c move ! l5s back & =? until a %>p image is =m$ on ! plate4 ,motion-picture ma*9es & /]eopticons likewise h l5ses t c be mov$ =w>d & back until !y =m a %>p focus on ! scre54 ,ev5 ! l5s 9 y\r eye has muscles t make x flatt] & r\nd]1 s t x c make a cle> image on ! s5sitive ret9a 9 ! back ( y\r eye4 ,! l5s 9 ! eyes ( eld]ly p (t5 becomes too h>d to be regulat$ 9 ?is way1 & s !y h to we> "o k9d ( glasses to see ?+s ne> !m cle>ly & ano!r k9d to see ?+s f> away4 ,! k9d ( l5s we h be5 talk+ ab\t is ! convex l5s4 ,convex means bulg+ out 9 ! middle4 ,!re are o!r k9ds ( l5ses1 "s flat on "o side & bulg+ out on ! o!r1 "s holl[$ out t[>d ! middle in/ead ( bulg+1 & s on4 ,b ! only l5s t mo/ p make mu* use ( 7except opticians7 is ! convex l5s t bulges out t[>d ! c5t]4 ,! convex l5s makes a cle> image & x is ! only k9d ( l5s t w d ?is4 ,illu/ration3 ,,fig4 #gh4 ,l5ses ( diff]5t k9ds4 ,,:y ,,y ,,c ,,set ,,fire ,,to ,,pap] ,,) ,a ,,magnify+ ,,glass4 ,a convex l5s br+s light to a focus1 & x also br+s radiant heat to a focus4 ,& t is :y y c set fire to ?+s by hold+ a convex l5s 9 ! sunlight s t ! light & heat are focus$ on some?+ t w burn4 ,all ! sun's radiant heat t /rikes ! l5s is br\ght practically to "o po9t1 & all ! light :i* is absorb$ at ?is po9t is *ang$ to heat4 ,:5 s mu* heat is conc5trat$ at "o po9t1 t po9t becomes hot en\gh to cat* fire4 ,,application #cf4 ,expla9 :y !re is a l5s 9 a mov+-picture ma*9e2 :y a convex l5s w burn y\r h& if y hold x betwe5 y\r h& & ! sun2 :y ! front ( a good cam]a is made s t x c be mov$ clos] to ! plate or f>!r away f x1 accord+ to ! di/ance ( ! object y are photograph+2 :y !re is a l5s 9 y\r eye4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #baa4 ,cut glass w>e sp>kles4 #bab4 ,an unpa9t$ floor becomes mu* dirti] & is h>d] to clean ?an a pa9t$ "o4 #bac4 ,if y spr9kle wet tea leaves on a rug be=e sweep+ x1 n s mu* du/ w be rais$4 #bad4 ,food leaves a spoon :5 ! spoon is /ruck %>ply ^u ! edge ( a /ewpan4 #bae4 ,an image is =m$ on ! photographic plate ( a cam]a4 #baf4 ,ripples 9 a pool di/ort ! image se5 9 x4 #bag4 ,cream rises to ! top ( a bottle ( milk4 #bah4 ,y\r eyes h to adju/ !mselves diff]5tly to see ?+s ne> by & to see ?+s at a di/ance4 #bai4 ,a vacuum clean] does n we> out a c>pet ne>ly z quickly z a broom or a c>pet sweep] does4 #bbj4 ,y c see a sunbeam 9 a du/y room4 ,,section #be4 ,magnification4 ,:y is x t ?+s look bigg] "u a magnify+ glass ?an "u o!r k9ds ( glass8 ,h[ does a telescope %[ y ! moon1 />s1 & planets8 ,h[ does a microscope make ?+s look l>g]8 ,ev]ybody kn[s1 ( c\rse1 t a convex l5s 9 ! "r position makes ?+s look l>g]4 ,p use convex l5ses to make pr9t look l>g] :5 !y read1 & = t reason su* l5ses are (t5 call$ read+ glasses4 ,= practical purposes x is n necess>y to und]/& h[ a convex l5s magnifies2 ! important ?+ is ! fact t x does magnify4 ,b y may be curi\s to "k j h[ a magnify+ glass works4 ,fir/1 y %\ld realize t ! image =m$ by a convex l5s is n always l>g] ?an ! object4 ,repeat ,exp]im5t #da1 b ?is "t move ! l5s f ne> ! c&le t[>d ! pap]1 pa/ ! po9t :]e x makes its fir/ cle> image4 ,keep mov+ ! l5s sl[ly t[>d ! pap] until a second image is =m$4 ,:i* image is l>g] ?an ! flame8 ,:i* is small]8 ,illu/ration3 ,,fig4 #gi4 ,a section ( ! eye4 ,! important po9t 9 ?is exp]im5t is = y to see t if ! l5s is ne>] to ! image on ! pap] ?an x is to ! c&le1 ! image is small] ?an ! c&le4 ,t is :y a photograph is usually small] ?an ! ?+ photograph$2 x w\ld be impossible to take a picture ( a h\se or a m\nta9 if ! l5s 9 ! cam]a gave a magnifi$ image4 #d,y\r eye is a small cam]a4 ,x has a l5s 9 ! front2 x is l9$ ) black2 & at ! back !re is a s5sitive "p on :i* ! picture is =m$4 ,?is s5sitive "p ( ! eye is call$ ! ret9a4 ,x is 9 ! back "p ( y\r eyeball & is made ( _m v s5sitive n]ve end+s4 ,:5 ! light /rikes ^! n]ve end+s1 x s5ds an impulse ?r\gh ! n]ves to ! back "p ( ! bra92 !n y "k t ! image is =m$4 ,&1 ( c\rse1 s9ce y\r eyeball is small & _m ( ! ?+s y see are l>ge1 ! image on ! ret9a mu/ be mu* small] ?an ! object itself1 & ?is is because ! l5s is s mu* ne>] to ! ret9a ?an x is to ! object4 ,footnote #d3 ,! foll[+ explanation may be omitt$ by any *ildr5 :o are n int]e/$ 9 x4 ,let su* *ildr5 skip to ! foot ( page #aef4 ,illu/ration3 ,,fig4 #hj4 ,h[ an image is =m$ on ! ret9a ( ! eye4 ,illu/ration3 ,,fig4 #ha4 ,a simpl] diagram %[+ h[ an image is =m$ 9 ! eye4 ,illu/ration3 ,,fig4 #hb4 ,a diagram %[+ h[ a read+ glass causes ?+s to look l>g] by mak+ ! image on ! ret9a l>g]4 ,illu/ration3 ,,fig4 #hc4 ,diagram %[+ h[ a read+ glass enl>ges ! image on ! ret9a4 ,m l9es are drawn 9 ?an 9 ,figure #hb4 ,y c und]/& magnification be/ by look+ at ,figures #hj1 #ha1 #hb1 & #hc4 ,9 ,figure #hj !re are a c&le flame1 ! l5s ( an eye1 & ! ret9a on :i* ! image is be+ =m$4 ,figure #ha is ! same z ,figure #hj1 ) all ! l9es left out except ! outside ones t g to ! l5s4 ,x is %[n 9 ?is way m]ely = ! sake ( simplicity4 ,all ! l9es really belong 9 ?is diagram z 9 ! fir/4 ,9 bo? diagrams ! size ( ! image on ! ret9a is ! di/ance betwe5 ! po9t :]e ! top l9e t\*es x & ! po9t :]e ! bottom l9e t\*es x4 ,9 ord] to make any?+ look l>g]1 we mu/ make ! image on ! ret9a l>g]4 ,a magnify+ glass1 or convex l5s1 if put 9 ! "r place1 w d ?is4 ,9 ! next diagram1 ,figure #hb1 we %all include ! magnify+ glass1 leav+ out all l9es except ! two outside ones %[n 9 ,figure #ha4 ,y w notice t ! magnify+ glass />ts to b5d ! l9es toge!r1 & t ! l5s 9 ! eye b5ds !m f>!r toge!r2 s !y cross soon]1 & ! image is l>g]4 ,figure #hc %[s m ( ! l9es drawn 94 ,illu/ration3 ,,fig4 #hd4 ,diagram ( a microscope4 ,! two important po9ts to notice are ^!3 ,fir/1 ! magnify+ glass is too close to ! eye = ! light to be br\ght to a focus be=e x rea*es ! eye2 ! light is b5t t[>d a focus1 b x rea*es ! eye be=e ! focus is =m$4 ,! focus is =m$ = ! fir/ "t on ! ret9a itself4 ,second1 ! magnify+ glass b5ds ! light on its way to y\r eye s t ! light crosses soon] 9 y\r eye & spreads out f>!r be=e x comes to a focus4 ,?is =ms ! l>g] image1 z y see 9 ! simple diagram1 ,figure #hb4 ,illu/ration3 ,,fig4 #he4 ,?is is ! way a concave mirror =ms a magnifi$ image4 ,illu/ration3 ,,fig4 #hf4 ,! concave mirror =ms an image ( ! burn+ c&le4 ,,h[ ,,! ,,microscope ,,works4 ,b ! microscope is diff]5t4 ,x works l ?is3 ,! fir/ l5s is put v ne> ! object :i* y are exam9+4 ,?is l5s br+s ! light f ! object to a focus & =ms an image1 mu* l>g] ?an ! object itself1 high up 9 ! tube4 ,if y held a piece ( pap] !re y w\ld see ! image4 ,b s9ce !re is no?+ !re to /op ! light1 x goes on up ! tube1 spread+ z x goes4 ,!n !re is ano!r l5s :i* cat*es ?is light & b5ds x inw>d on its way to y\r eye1 j z any magnify+ glass does4 ,next ! l5s 9 ! eye =ms an image on ! ret9a4 ,! diagram 7,fig4 #hd7 w make ?is cle>]4 7,a real microscope is n s simple1 ( c\rse1 & usually has two l5ses :]ev] ! diagram %[s "o47 ,:at actually happ5s is t ! fir/ l5s makes an image _m times z big z ! object2 !n y look at ?is image ?r\gh a magnify+ glass1 s t ! object is made to look v mu* l>g] ?an x really is4 ,t is :y y c see blood corpuscles & g]ms & cells ?r\gh a microscope1 :5 y _c see !m at all ) y\r nak$ eye4 ,illu/ration3 ,,fig4 #hg4 ,! great telescope ( ! ,y]kes ,obs]vatory at ,lake ,g5eva1 ,wiscons94 ,a ,,mirror ,,t ,,magnifies4 ,a convex l5s is n ! only ?+ t c magnify4 ,a concave mirror1 :i* is "o t is holl[$ out t[>d ! middle1 does ! same ?+4 ,:5 light is reflect$ by su* a mirror1 x acts exactly z if x _h gone ?r\gh a convex l5s 7,fig4 #he74 ,,exp]im5t #di4 ,place ! light$ c&le & ! pap] ab\t #d feet ap>t1 z y did 9 ,exp]im5t #dg4 ,hold a concave mirror back ( ! c&le 7s t ! c&le is betwe5 ! mirror & ! pap]72 !n move ! mirror back1 ! mirror ca/+ ! reflection ( ! c&le light on ! pap]1 until a cle> image ( ! c&le is =m$4 ,look at y\r image 9 ! concave mirror4 ,does x look l>g] or small] ?an y8 ,,h[ ,,telescopes ,,are ,,made4 ,a/ronom]s use convex l5ses 9 "s ( _! telescopes2 9 o!rs1 call$ reflect+ telescopes1 !y use concave mirrors4 ,bo? d ! same "w1 mak+ ! moon1 ! planets1 & ! sun look mu* l>g] ?an !y o!rwise w\ld4 ,,application #cg4 ,expla9 h[ a read+ glass makes pr9t look l>g]2 h[ y c see g]ms ?r\gh a microscope2 :at k9d ( mirror w magnify2 :at k9d ( l5s w magnify4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bba4 ,! wat] t =ms ra9 comes f ! ocean1 yet ! ra9 is n salty4 #bbb4 ,iron gl[s :5 x is v hot4 #bbc4 ,y c />t a fire ) sunlight by hold+ a read+ glass at ! "r di/ance above ! fuel4 #bbd4 ,big telescopes make x possible = u to see 9 detail ! surface /ructure ( ! moon4 #bbe4 ,a room is light] if x has :ite walls ?an if x has d>k walls4 #bbf4 ,iron is heat$ by a blacksmi? be=e he %apes x4 #bbg4 ,a d5ti/'s mirror is concave2 he sees y\r tee? enl>g$ 9 x4 #bbh4 ,good p5hold]s usually h cork or rubb] tips4 #bbi4 ,a man's suit becomes %9y :5 x gets old4 #bcj4 ,:5 y look at a w9d[ f ! sidewalk1 y frequ5tly see images ( ! h\ses across ! /reet4 ,,section #bf4 ,scatt]+ ( light3 ,diffusion4 ,:y is x t on a d>k day ! sun _c be se5 ?r\gh light cl\ds8 ,:y d n ! />s come out 9 ! daytime8 ,if y 7 on ! moon1 y c\ld see ! />s 9 ! daytime4 ,! sun w\ld be %9+ ev5 m brightly ?an x does "h1 b ! sky ar\nd ! sun w\ld be pit* black1 except = ! />s %9+ out ( its blackness4 ,! reason is t !re is no air on ! moon to scatt] ! light4 ,,:y ,,we ,,_c ,,see ,,! ,,/>s ,,9 ,,! ,,daytime4 ,mo/ ( ! sun's light t comes to ! e>? rea*es u r directly2 t is :y we c see ! image ( ! sun4 ,b "p ( ! sunlight is scatt]$ by p>ticles ( air1 & t is :y ! :ole sky is bright 9 ! daytime4 ,y "k1 ( c\rse1 t ! blue sky is only ! air t surr\nds ! e>?4 ,en\gh ( ! light is scatt]$ ar\nd to make ! sky z bright z ! />s look f "h2 s we _c see ! />s ?r\gh ! sky 9 ! daytime4 ,,h[ ,a ,,cl\d ,,c ,,hide ,,! ,,sun ,,)\t ,,cutt+ ,,(f ,,all ,,its ,,light4 ,:5 a cl\d drifts betwe5 u & ! sun1 we no long] see ! sun2 yet ! e>? does n become d>k4 ,! sun's light is evid5tly /ill rea*+ u4 ,! cl\d is made ( millions ( v t9y droplets ( wat]4 ,:5 ! sunlight /rikes ! curv$ sides ( ^! droplets1 x is reflect$ at all angles accord+ to ! way x /rikes1 z %[n 9 ,figure #hi4 ,illu/ration3 ,,fig4 #hh4 ,! sunlight is scatt]$ 7diffus$7 by ! cl\ds4 ,! photograph %[s 9 ! =egr\nd ! ,p>liam5t ,build+s1 ,london1 ,engl&4 ,"s ( ! light is reflect$ back into ! sky2 t is :y ev]y?+ becomes d>k] :5 ! sun goes beh9d a cl\d2 b mu* ( ! light comes ?r\gh to u1 at all sorts ( slants4 ,:5 x comes all higgl$y-piggl$y & crisscross l ?is1 no l5s c put x toge!r aga92 x is z hopelessly brok5 up z ,humpty-,dumpty 04 ,b mu* ( ! light gets "h j ! same2 s we see x )\t see+ ! =m ( ! sun4 ,light t _c be br\ght to a focus is call$ scatt]$ or diffus$ light4 ,:5 y look ?r\gh a gr\nd-glass electric lamp1 y _c see ! filam5t2 ! light pass+ ?r\gh all ! r\gh p>ts ( ! glass gets s scatt]$ t y _c br+ x to a focus4 ,!re=e1 no image ( ! filam5t 9 ! inc&esc5t lamp c be =m$ on ! ret9a ( y\r eye4 ,illu/ration3 ,,fig4 #hi4 ,h[ ! droplets 9 a cl\d scatt] ! rays ( light4 ,a piece ( :ite pap] reflects practically all ! light t /rikes x4 ,yet y _c see y\rself 9 a piece ( ord9>y :ite pap]4 ,! tr\ble is t ! pap] is too r\gh2 !re are too _m little unev5 places t reflect ! light at all sorts ( angles2 ! light is scatt]$ & ! l5s 9 y\r eye _c br+ x to a focus4 ,,application #ch4 ,expla9 :y a scrim curta9 w keep p f see+ into a room1 b w n %ut ! light out2 :y curta9s s(t5 ! light ( a room2 :y indirect light+ 7i4e4 light ?r[n up aga9/ ! ceil+ & !n reflect$ d[n into ! room by ! r\gh ceil+7 is bett] = y\r eyes ?an is ! old-"t direct light+4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bca4 ,! alcohol =m$ by ! yea/ 9 mak+ bread light is practically all gone by ! "t ! bread is bak$4 #bcb4 ,! oceans d n fl[ (f ! e>? at ! s\? pole4 #bcc4 ,lamp globes (t5 h fro/$ bottoms4 #bcd4 ,a damp du/ clo? w take up ! du/1 )\t mak+ x fly4 #bce4 ,! />s tw9kle :5 _! light passes ?r\gh ! mov+ air curr5ts t surr\nd ! e>?4 #bcf4 ,%e>s = cutt+ t9 & metal h long h&les & %ort blades4 #bcg4 ,a co9 at ! bottom ( a glass ( wat] seems rais$ :5 y look at x a little f "o side4 #bch4 ,y h to brace y\r feet to r[ well4 #bci4 ,light f ! nor!rn "p ( ! sky1 :]e ! sun is n1 does n make %>p %ad[s4 #bdj4 ,pok]s & lift]s = /ove lids (t5 h op5 spiral h&les4 ,,section #bg4 ,color4 ,:at makes ! ocean look gre5 9 "s places & blue 9 o!rs8 ,:at makes ! sky blue8 ,:at causes mat]ial to be color$8 ,:at makes a ra9b[8 ,:at is color8 ,illu/ration3 ,,fig4 #ij4 ,mak+ a ra9b[ on ! wall4 ,color is m]ely a k9d ( light4 ,we say t a sweat] is r$2 really ! sweat] is n r$1 b ! light t x reflects to our eyes is r$4 ,we speak ( a piece ( r$ glass1 b ! glass is n r$2 x is ! light t x lets pass ?r\gh x t is r$4 ,:ite is n really a color2 all colors put toge!r make :ite4 ,exp]im5ts #ej & #ea w prove ?is4 ,illu/ration3 ,,fig4 #ia4 ,! prism sep>ates ! :ite light into ! ra9b[ colors4 ,,exp]im5t #ej4 ,hold a prism 9 ! sunlight by ! w9d[ & make a ra9b[ on ! wall4 ,! diagram "h %[n illu/rates h[ ! prism breaks up ! s+le beam ( :ite light into diff]5t-color$ beams ( light4 ,illu/ration3 ,,fig4 #ib4 ,:5 ! :eel is rapidly :irl$ ! colors bl5d to make :ite4 ,,exp]im5t #ea4 ,rotate ! color disk on ! rotator & wat* x4 ,make x g fa/] & fa/] until all ! colors are p]fectly m]g$4 ,:at color d y get by comb9+ all ! colors ( ! ra9b[8 ,if ! colors on ! disk 7 p]fectly cle> ra9b[ colors1 9 exactly ! same proportion z 9 ! ra9b[1 ! :irl+ w\ld give a :ite ( dazzl+ purity4 ,s9ce y c break up pure :ite light into all ! colors1 & s9ce y c comb9e all ! colors & get pure :ite light1 x is cle> t :ite light is made up ( all ! colors4 99 99 99 99 99 ,z we h already said1 light is probably vibrations or waves ( e!r4 ,light made ( ! longe/ waves t we c see is r$4 ,if ! waves are a little %ort]1 ! light is orange2 if !y are %ort] yet1 x is yell[2 /ill %ort]1 gre52 %ort] /ill1 blue2 :ile ! %orte/ waves t we c see are ^? ( violet light4 ,black is n a color at all2 x is ! abs5ce ( light4 ,we say ! night is black :5 we _c see any?+4 ,a deep hole looks black because practically no light is reflect$ up f its dep?s4 ,:5 y see any?+ black1 y really see ! ?+s ar\nd x & ! p>ts ( x t are n p]fectly black4 ,a pair ( %oes1 = in/ance1 has p>ticles ( gray du/ on !m2 or if !y are v %9y !y reflect "p ( ! light t /rikes !m z a :ite high-light4 ,b ! really black "p ( y\r %oes w\ld be invisible aga9/ an equally black backgr\nd4 ,a black ?+ absorbs ! light t /rikes x & turns x to heat4 ,"h is an exp]im5t t w prove ?is to y3 ,,exp]im5t #eb4 7a7 ,on a sunny day1 take ?ree bottles1 all ( ! same size & %ape1 & p\r wat] out ( a pit*] or pan into ea* bottle4 ,d n run ! wat] directly f ! faucet into ! bottle1 because sometimes t :i* comes out ( ! faucet fir/ is w>m] or cold] ?an t :i* foll[s2 9 ! pit*] or pan x w all be mix$ toge!r1 & s y c be sure t ! wat] 9 all ?ree bottles is ( ! same temp]ature to beg9 )4 ,wrap a piece ( :ite cotton clo? twice ar\nd "o bottle2 a piece ( r$ or gre5 cotton clo? ( ! same weight twice ar\nd ! second bottle1 & a piece ( black cotton clo? ( ! same weight twice ar\nd ! ?ird bottle1 fa/5+ ea* ) a rubb] b&4 ,set all ?ree bottles side by side 9 ! sunlight1 ) #b or #c in*es ( space betwe5 !m4 ,leave !m = ab\t an h\r4 ,n[ put a !rmomet] into ea* to see :i* is w>me/ & :i* is lea/ w>m4 ,f :i* bottle has mo/ ( ! light be5 reflect$ back into ! air by ! clo? ar\nd x8 ,:i* clo? absorb$ mo/ ( ! light & *ang$ x into heat8 ,does ! color$ clo? absorb m or less light ?an ! :ite "o8 ?an ! black "o8 ,illu/ration3 ,,fig4 #ic4 ,:i* color is w>me/ 9 ! sunlight8 7b7 ,on a sunny day :5 !re is sn[ on ! gr\nd1 spread ?ree pieces ( cotton clo?1 all ( ! same size & ?ickness1 "o :ite1 "o r$ or gre51 & "o black1 on top ( ! sn[1 :]e ! sun %9es on !m4 ,wat* !m = a "t4 ,"u :i* does ! sn[ melt fir/8 ,! :ite clo? is :ite because x reflects all colors back at once4 ,x !re=e absorbs practically no light4 ,b ! reason ! black clo? looks black is t x reflects almo/ none ( ! colors--x absorbs !m all & *anges !m to heat4 ,! color$ clo? reflects j ! r$ or ! gre5 light & absorbs ! re/4 ,maybe y w und]/& color bett] if x is expla9$ 9 ano!r way4 ,suppose ,i ?r[ balls ( all colors to y1 hav+ tra9$ y to keep all ! balls except ! r$ ones4 ,i ?r[ y a blue ball2 y keep x4 ,i ?r[ a r$ ball2 y ?r[ x back4 ,i ?r[ a gre5 ball2 y keep x4 ,i ?r[ a yell[ ball2 y keep x4 ,i ?r[ two balls at once1 yell[ & r$2 y keep ! yell[ & ?r[ back ! r$4 ,i ?r[ a blue & yell[ ball at ! same "t2 y keep bo? balls4 ,n[ suppose ,i *ange ?is a little4 ,in/ead ( ?r[+ balls1 ,i %all ?r[ lights to y4 ,y are tra9$ always to ?r[ r$ light back to me & always to keep 7absorb7 all o!r k9ds ( light4 ,i ?r[ a blue light2 y keep x1 & ,i get no light back4 ,i ?r[ a r$ light2 y ?r[ x back to me4 ,i ?r[ a gre5 light2 y keep x1 & ,i get no light back4 ,i ?r[ a yell[ light2 y keep x1 & ,i get no light back4 ,i ?r[ two lights at ! same "t1 yell[ & r$2 y keep ! yell[ & ?r[ back only ! r$4 ,b yell[ & r$ toge!r make orange2 s :5 ,i ?r[ an orange light1 y ?r[ back ! r$ "p ( x & keep ! yell[4 ,n[ if we suppose t in/ead ( ?r[+ lights to y ,i ?r[ !m to molecules ( dye :i* are tra9$ to ?r[ back ! r$ lights & keep all ! o!r k9ds 7absorb !m & *ange !m to heat71 we c und]/& :at ! dye 9 a r$ sweat] does4 ,! dye is n really tra9$1 ( c\rse1 b = a reason :i* we d n entirely und]/&1 "s k9ds ( dye always ?r[ back 7reflect7 any r$ t is 9 ! light t %9es on !m1 b !y keep all o!r k9ds ( light1 *ang+ !m to heat4 ,o!r dyes or color+ matt] always ?r[ back any gre5 t is 9 ! light t %9es on !m1 keep+ ! o!r colors4 ,blue color+ matt] ?r[s back only ! blue "p ( ! light1 & s on ?r\gh all ! colors4 ,s if y ?r[ a :ite light1 :i* conta9s all ! colors1 on a r$ sweat]1 ! dye 9 ! sweat] picks out ! r$ "p ( ! :ite light & ?r[s t back to y\r eyes 7reflects x to y7 b x keeps ! re/ ( ! colors ( ! :ite light1 *ang+ !m to heat2 & s9ce only ! r$ "p ( ! light is reflect$ to y\r eyes1 t is ! only "p ( x t y c see2 s ! sweat] looks r$4 ,! gre5 sub/ance 7*lorophyll7 9 grass acts 9 ! same way2 only x ?r[s ! gre5 "p ( ! sunlight back to y\r eyes1 keep+ ! re/2 s ! "p ( ! light t rea*es y f ! grass is ! gre5 light1 & ! grass looks gre54 ,any?+ :ite1 l a piece ( pap]1 reflects all ! light t /rikes x2 s if all ! colors 7:ite light7 /rike x1 all are reflect$ to y\r eyes & ! object looks :ite4 ,y h look$ at p "u ! m]cury-vapor lights 9 photo-po/al /udios1 h y n8 ,! lights are long1 incl9$ tubes :i* gl[ ) a gre5i%-violet light4 ,no matt] h[ good ! color ( a p]son is 9 ord9>y light1 9 t light x is gha/ly4 ,illu/ration3 ,,fig4 #id4 ,a m]cury-vapor lamp4 ,g into ! kit*5 tonight1 light a burn] ( ! gas /ove1 turn out ! light & spr9kle salt on ! blue gas flame4 ,! flame w leap up1 yell[4 ,look at y\r h&s1 at "s "o's lips1 at a piece ( r$ clo?1 9 ?is light4 ,does any?+ look r$8 ,! reason :y no?+ looks p9k or r$ 9 ^! two k9ds ( light is ?is3 ,! light giv5 by gl[+ salt vapor or m]cury vapor has no r$ 9 x2 if y tri$ to make a ra9b[ f x ) a prism1 y w\ld f9d no r$ or orange color 9 x4 ,a ?+ looks r$ :5 x absorbs all ! p>ts ( ! light t are n r$ & reflects ! r$ light to y\r eyes4 ,if !re is no r$ 9 ! light to reflect1 obvi\sly a ?+ _c look r$ 9 t light4 ,:5 y look ?r\gh a piece ( color$ glass1 ! case is some:at diff]5t4 ,a piece ( blue glass1 = in/ance1 acts z a sort ( /ra9]4 ,! color+ matt] 9 x lets ! blue light ?r\gh x1 b x holds back 7absorbs7 ! o!r k9ds ( light4 ,s if y look ?r\gh a piece ( blue glass y see ev]y?+ blue2 t is1 only ! blue "p ( ! light f diff]5t objects c rea* y\r eyes ?r\gh ?is k9d ( glass4 ,any?+ t is transp>5t & color$ acts 9 a simil> way4 ,,:y ,,! ,,sky ,,is ,,blue4 ,& t is :y ! sky looks blue4 ,air holds back all colors ( light except blue2 t is1 x holds !m back a little4 ,a room full ( air holds ! colors back h>dly at all4 ,a few miles ( air hold !m back m2 m\nta9s 9 ! di/ance look blui% because only ! blue light f !m c rea* y ?r\gh ! air4 ,! hundr$ or m miles ( air above y hold back a consid]able am\nt ( ! o!r colors ( light1 lett+ ?r\gh mu* m ( blue ?an ( any o!r color4 ,s ! sky looks blue2 t is1 :5 ! air scatt]s ! sunlight above y1 x is *iefly ! blue p>ts ( ! sunlight t x all[s to rea* y\r eyes4 ,,:y ,,bodies ,,( ,,wat] ,,look ,,gre5 ,,9 ,,"s ,,places ,,& ,,blue ,,9 ,,o!rs4 ,wat] acts 9 a simil> way1 b x lets ! gre5 light ?r\gh in/ead ( ! blue4 ,a little wat] holds back 7absorbs7 ! o!r colors s slightly t y _c notice ! effect 9 a glass ( wat]4 ,b 9 a swimm+ tank full ( wat]1 or 9 a lake or an ocean1 y c notice x decid$ly :5 y look /raight d[n into ! wat] itself4 ,:5 y look at a smoo? body ( wat] at a slant on a cle> day1 ! blue sky is reflect$ to y & ! wat] looks blue in/ead ( gre54 ,& x may ev5 look blue :5 y look /raight d[n 9 x if x is too deep = y to see ! bottom & ! sky is reflect$ f ! surface4 ,,:y ,,! ,,sky ,,is ,,(t5 ,,r$ ,,at ,,sunset4 ,du/ lets m ( r$ & yell[ light ?r\gh ?an ( any o!r color1 & = ?is reason !re is mu* r$ & yell[ 9 ! sunset4 ,j be=e ! sun sets1 x %9es ?r\gh ! l[1 du/y air4 ,! du/ filt]s out mo/ ( ! light except ! r$ & yell[4 ,! r$ light & yell[ light are reflect$ by ! cl\ds 7= ! cl\ds are !mselves :ite2 t is1 !y reflect all ! colors t /rike !m71 & y h ! beautiful sunset cl\ds4 ,sometimes !re is a purple 9 ! sunset1 & ev5 gre54 ,b s9ce ! air itself is blue 7t is1 x lets mo/ly blue light g ?r\gh71 x is easy to see h[ ?is blue c comb9e ) ! r$ or yell[ t ! du/ lets ?r\gh1 to =m purple or gre54 ,b we c\ld n h sunset colors or all ! colors we see on e>?1 if x 7 n t ! sunlight is mo/ly :ite--t x conta9s all colors4 ,& t1 too1 is :y we c h a ra9b[4 ,,h[ ,,ra9b[s ,,are ,,=m$4 ,y already "k fairly well h[ a ra9b[ is =m$1 s9ce y made an imitation ( "o ) a prism4 ,a ra9b[ appe>s 9 ! sky :5 ! sun %9es ?r\gh ! ra92 ! pla9 :ite light ( ! sun is divid$ up into r$1 orange1 yell[1 gre51 blue1 indigo1 & violet4 ,z ! :ite light ( ! sun passes ?r\gh ! ra9drops1 ! violet "p ( ! light is b5t m ?an any ( ! re/1 ! indigo "p is b5t n q s mu*1 & s on to ! r$1 :i* is b5t lea/ ( all4 ,s all ! colors fan out f ! s+le beam ( :ite light & =m a b& ( color1 :i* we call ! ra9b[4 ,illu/ration3 ,,fig4 #ie4 ,expla9 :y ! break]s are :ite & ! sea gre5 or blue4 ,,h[ ,,we ,,c ,,tell ,,:at ,,! ,,sun ,,& ,,/>s ,,are ,,made ,,(4 ,:5 a gas or vapor becomes hot en\gh to give (f light 7:5 x is inc&esc5t71 x does n give (f :ite light b light ( diff]5t colors4 ,an exp]im5t w let y see ?is = y\rself4 ,,exp]im5t #ec4 ,spr9kle a little copp] sulfate 7blue/one7 9 ! flame ( a ,buns5 burn]4 ,:at color does x make ! flame8 ,copp] vapor always gives ?is gre5i%-blue light :5 x is heat$4 ,! photograph]'s m]cury-vapor light gave a gre5i%-violet gl[4 ,:5 y burn salt or soda 9 a gas flame1 y rememb] t y get a cle> yell[ light4 ,by break+ up ^! lights1 some:at z y broke up ! sunlight ) ! prism1 *emi/s & a/ronom]s c tell :at k9d ( gas is gl[+4 ,! in/rum5t !y use to break up ! light into its diff]5t colors is call$ a spectroscope1 & ! b& ( colors =m$ is call$ ! spectrum4 ,) ! spectroscope !y exam9e ! light t comes f ! sun & />s & by ! colors ( ! spectra !y c tell :at ^! f>-di/ant bodies are made (4 ,,application #ci4 ,if y 7 go+ to ! tropics1 w\ld x be bett] to we> outside clo!s t 7 :ite or black8 ,,application #dj4 ,a danc] 0 to dance 9 a spotlight on ! /age4 ,! light 0 to *ange colors con/antly4 ,%e want$ h] robe to reflect ea* color t 0 ?r[n on x4 ,%\ld %e h worn a robe ( r$1 yell[1 :ite1 gre51 or blue8 ,,application #da4 ,if y look$ ?r\gh a r$ glass at a purple fl[] 7purple is r$ mix$ ) blue71 w\ld ! fl[] look r$1 blue1 purple1 black1 or :ite8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bda4 ,m]cury is sep>at$ f its ore by heat+ ! ore s /rongly t ! m]cury rises f x z a vapor4 #bdb4 ,ho?\ses are built ( glass4 #bdc4 ,a ra9b[ is sometimes se5 9 ! spray ( a g>d5 hose4 #bdd4 ,y\r feet become hot :5 y\r %oes are be+ poli%$4 #bde4 ,doors into (fices usually h w9d[s ( gr\nd glass or fro/$ glass4 #bdf4 ,op]a glasses are ( value to ^? sitt+ at a di/ance f ! /age4 #bdg4 ,9 ord] to see cle>ly ?r\gh op]a glasses1 y h to adju/ !m4 #bdh4 ,x is w>m inside an ,eskimo's hut al?\gh x is built ( ice & sn[4 #bdi4 ,x is usually cool] on a lawn ?an on dry gr\nd4 #bej4 ,black clo!s are w>m] 9 ! sunlight ?an clo!s ( any o!r color4 ,,*apt] ,,six ,,s\nd ,,section #bh4 ,:at s\nd is4 ,:at makes a dictaphone or a phonograph repeat y\r words8 ,:at makes ! w9d h[l :5 x bl[s ?r\gh ! bran*es ( trees8 ,:y c y he> an approa*+ tra9 bett] if y put y\r e> to ! rail8 ,if y 7 to l& on ! moon tonight1 & _h ) y a tank conta9+ a supply ( air :i* y c\ld brea! 7= !re is no air to speak ( on ! moon71 y might try to speak4 ,b y w\ld f9d t y _h lo/ y\r voice completely4 ,y c\ld n say a ^w4 ,y w\ld op5 & close y\r m\? & n a s\nd w\ld come4 ,!n y might try to make a noise by clapp+ y\r h&s2 b t w\ld n "w4 ,y c\ld n make a s\nd4 ,am ,i deaf & dumb8 y might wond]4 ,! :ole tr\ble w\ld lie 9 ! fact t ! moon has practically no air4 ,& s\nd is usually a k9d ( motion ( ! air1--hundr$s ( quick1 %>p puffs 9 a second1 s close toge!r t we _c feel !m ) any?+ less s5sitive ?an ! t9y n]ves 9 our e>s4 ,if y c once realize ! fact t s\nd is a s]ies ( quick1 %>p puffs ( air1 or to use a m sci5tific t]m1 vibrations ( air1 x w be easy = y to und]/& mo/ ( ! laws ( s\nd4 ,a phonograph seems almo/ miracul\s4 ,yet x works on an exce$+ly simple pr9ciple4 ,:5 y talk1 ! brea? pass+ out ( y\r ?roat makes ! vocal cords vibrate4 ,^! & y\r tongue & lips make ! air 9 front ( y vibrate4 ,:5 y talk into a dictaphone horn1 ! vibrat+ air causes ! ne$le at ! small end ( ! horn to vibrate s t x traces a wavy l9e 9 ! s(t wax ( ! cyl9d] z ! cyl9d] turns4 ,!n :5 y run ! ne$le ov] ! l9e aga9 x foll[s ! id5tical track made :5 y talk$ into ! horn1 & x vibrates back & =? j z at fir/2 ?is makes ! air 9 ! horn vibrate exactly z :5 y talk$ into ! horn1 & y h ! same s\nd4 ,all ?is goes back to ! fundam5tal pr9ciple t s\nd is vibrations ( air2 diff]5t k9ds ( s\nds are simply diff]5t k9ds ( vibrations4 ,! next exp]im5ts w prove ?is4 ,,exp]im5t #ed4 ,turn ! rotator rapidly1 hold+ ! corn] ( a piece ( /iff pap] aga9/ ! holes 9 ! disk4 ,z y turn fa/]1 does ! s\nd become high] or l[]8 ,keep turn+ at a /eady rate & move y\r pap] f ! inn] r[ ( holes to ! out] r[ & back aga94 ,:i* r[ has ! mo/ holes 9 x8 ,:i* makes ! highe/ s\nd8 ,hold y\r pap] aga9/ ! tee? at ! edge ( ! disk4 ,is ! pit* high] or l[] ?an be=e8 ,bl[ ?r\gh a bl[pipe aga9/ ! diff]5t r[s ( holes :ile ! disk is be+ :irl$4 ,z ! holes make ! air vibrate d y get any s\nd8 ,?is exp]im5t %[s t by mak+ ! air vibrate y get a s\nd4 ,! next exp]im5t w %[ t :5 y h s\nd y are gett+ vibrations4 ,,exp]im5t #ee4 ,tap a tun+ =k aga9/ ! desk1 !n hold ! prongs lightly aga9/ y\r lips4 ,c y feel !m vibrate8 ,tap x aga91 & hold ! =k close to y\r e>4 ,c y he> ! s\nd8 ,illu/ration3 ,,fig4 #if4 ,an int]e/+ exp]im5t 9 s\nd4 ,! exp]im5t :i* foll[s w %[ t we usually mu/ h air to d ! vibrat+ to c>ry ! s\nd4 ,,exp]im5t #ef4 ,make a pad ( n less ?an a doz5 ?icknesses ( s(t clo? s t y c /& an al>m clock on x on ! plate ( ! air pump4 ,! pad is to keep ! vibrations ( ! al>m f mak+ ! plate vibrate4 ,a /ill bett] way w\ld be to set a tripod on ! plate ( ! air pump & to susp5d ! al>m clock f ! tripod by a rubb] b&4 ,set ! al>m s t x w r+ 9 #c or #d m9utes1 put x "u ! bell j>1 & pump out ! air4 ,be=e ! al>m goes (f1 be sure t ! air is almo/ completely pump$ out ( ! j>4 ,c y he> ! bell r+8 ,di/+ui% betwe5 a dull trill+ s\nd caus$ by ! j>r+ ( ! air pump :5 ! al>m is on1 & ! actual r++ s\nd ( ! bell4 ,illu/ration3 ,,fig4 #ig4 ,:5 ! air is pump$ out ( ! j>1 y _c he> ! bell r+4 ,! exp]im5t j complet$ %[s h[ we "k !re w\ld be no s\nd on ! moon1 s9ce !re is practically no air ar\nd x4 ,! next exp]im5t w %[ y m ab\t ! way 9 :i* phonographs "w4 ,,exp]im5t #eg4 ,put a blank cyl9d] on ! dictaphone1 adju/ ! record+ 7cutt+7 ne$le & diaphragm at ! end ( ! tube1 />t ! motor1 & talk into ! dictaphone4 ,%ut (f ! motor1 remove ! cutt+ ne$le1 & put on ! reproduc+ ne$le 7! cutt+ ne$le1 be+ %>p1 w\ld spoil ! cyl9d]74 ,/>t ! reproduc+ ne$le :]e ! record+ ne$le />t$1 turn on ! motor1 & li/5 to y\r own voice4 ,notice t 9 ! dictaphone ! air waves ( y\r voice are all conc5trat$ into a small space z !y g d[n ! tube4 ,at ! end ( ! tube is a diaphragm1 a flat disk :i* is ela/ic & vibrates back & =? v easily4 ,! air waves f y\r voice w\ld n vibrate ! ne$le itself en\gh to make any record2 b !y vibrate ! diaphragm1 & ! ne$le1 be+ fa/5$ rigidly to x1 vibrates ) x4 ,illu/ration3 ,,fig4 #ih4 ,mak+ a phonograph record on an old-fa%ion$ phonograph4 ,9 ! same way1 :5 ! reproduc+ ne$le vibrates z x goes ov] ! track made by ! cutt+ ne$le1 x w\ld make air vibrations too slight = y to he> if x 7 n fa/5$ to ! diaphragm4 ,:5 ! diaphragm vibrates ) ! ne$le1 x makes a mu* l>g] surface ( air vibrate ?an ! ne$le alone c\ld4 ,!n ! tube1 l an e> trumpet1 ?r[s all ! air vibrations 9 "o direction1 s t y he> ! s\nd easily4 ,,exp]im5t #eh4 ,put a clean :ite %eet ( pap] ar\nd ! record+ drum1 pa/+ ! two ends toge!r to hold x 9 place4 ,put a small piece ( gum camphor on a di% j "u ! pap]1 light x1 & turn ! drum s t all p>ts w be ev5ly smok$4 ,be sure to turn x rapidly en\gh to keep ! pap] f be+ burn$4 ,melt a piece ( glass ov] a burn] & draw x out into a ?read4 ,break (f ab\t #h in*es ( ?is glass ?read & tie x firmly ) cotton ?read to ! edge ( "o prong ( a tun+ =k4 ,clamp ! top ( ! tun+ =k firmly above ! smok$ drum1 adju/+ x s t ! po9t ( ! glass ?read re/s on ! smok$ pap]4 ,turn ! h&le slightly to see if ! glass is mak+ a m>k4 ,if x is n1 adju/ x s t x w4 ,n[ let "s "o turn ! cyl9d] quickly & /eadily4 ,:ile x is turn+1 tap ! tun+ =k on ! prong :i* has n ! glass ?read fa/5$ to x4 ,! glass po9t %\ld trace a :ite1 wavy l9e ?r\gh ! smoke on ! pap]4 ,if x does n1 keep on try+1 adju/+ ! app>atus until ! po9t makes a wavy l9e4 ,illu/ration3 ,,fig4 #ii4 ,a mod]n dictaphone4 ,mak+ a record 9 ?is way is1 on a l>ge scale1 almo/ exactly l ! mak+ ( a phonograph record4 ,! smok$ pap] on :i* a trac+ c easily be made z x turns is l ! s(t wax cyl9d]4 ,! glass ne$le is l ! record+ ne$le ( a phonograph4 ,! *ief diff]5ce is t y h /ruck ! tun+ =k to make x & ! ne$le vibrate1 in/ead ( mak+ x vibrate by air waves set 9 motion by y\r talk+4 ,x is because ^! vibrations ( ! tun+ =k are m p[]ful & l>g] ?an are ^? ( ! record+ ne$le ( a phonograph t y c see ! record on ! record+ drum1 :ile y _c see x cle>ly on ! phonograph cyl9d]4 ,illu/ration3 ,,fig4 #ajj4 ,h[ ! app>atus is set up4 ,9 all ord9>y circum/ances1 s\nd is ! vibration ( air4 ,b 9 swimm+ we c he> ) our e>s "u wat]1 & fi%es he> )\t any air4 ,s1 to be accurate1 we %\ld say t s\nd is vibrations ( any k9d ( matt]4 ,& ! vibrations travel bett] 9 mo/ o!r k9ds ( matt] ?an !y d 9 air4 ,vibrations move r sl[ly 9 air1 comp>$ ) ! spe$ at :i* !y travel 9 o!r sub/ances4 ,x takes s\nd ab\t #e seconds to g a mile 9 air2 9 o!r words1 x w\ld g #ab miles :ile an express tra9 w5t "o4 ,b x travels fa/] 9 wat] & /ill fa/] 9 any?+ h>d l /eel4 ,t is :y y c he> ! noise ( an approa*+ tra9 bett] if y put y\r e> to ! rail4 ,illu/ration3 ,,fig4 #aja4 ,:5 ! tun+ =k vibrates1 ! glass ne$le makes a wavy l9e on ! smok$ pap] on ! drum4 ,,:y ,,we ,,see ,,/eam ,,rise ,,be=e ,,we ,,he> ,a ,,:i/le ,,bl[4 ,b ev5 ?r\gh /eel1 s\nd does n travel ) any?+ l ! spe$ ( light4 ,9 ! "t t x takes s\nd to g a mile1 light goes hundr$s ( ?\s&s ( miles1 easily com+ all ! way f ! moon to ! e>?4 ,t is :y we see ! /eam rise f ! :i/le ( a tra9 or a boat be=e we he> ! s\nd4 ,! s\nd & ! light />t toge!r2 b ! light t %[s u ! /eam is 9 our eyes almo/ at ! in/ant :5 ! /eam leaves ! :i/le2 ! s\nd lags beh9d1 & we he> x lat]4 ,,application #db4 ,expla9 :y a bell rung 9 a vacuum makes no noise2 :y ! click+ ( two /ones "u wat] s\nds l\d] if y\r head is "u wat]1 ?an ! click+ ( ! two /ones 9 ! air s\nds if y\r head is 9 ! air2 :y y he> a buzz+ s\nd :5 a bee or a fly comes ne> y2 h[ a phonograph c reproduce s\nds4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bea4 ,! pa9t on woodwork bli/]s :5 hot4 #beb4 ,y c screw a nut on a bolt v mu* tight] ) a wr5* ?an ) y\r f+]s4 #bec4 ,:5 a pipe is be+ repair$ 9 ! basem5t ( a h\se1 y c he> a scrap+ noise 9 ! faucets up/airs4 #bed4 ,sunsets are unusually r$ aft] volcanic eruptions4 #bee4 ,?und] %akes a h\se4 #bef4 ,%oot+ />s are really /ones fly+ ?r\gh space4 ,:5 !y come ne> ! e>?1 x pulls !m swiftly d[n ?r\gh ! air4 ,expla9 :y !y gl[4 #beg4 ,at night x is difficult to see out ?r\gh a clos$ w9d[ ( a room 9 :i* a lamp is light$4 #beh4 ,:5 !re is a breeze y _c see cle> reflections 9 a lake4 #bei4 ,rubb+ ) co>se s&pap] makes r\gh wood smoo?4 #bfj4 ,a b[ is b5t backw>d to make ! arr[ g =w>d4 ,,section #bi4 ,e*oes4 ,:5 y put a sea %ell to y\r e>1 h[ is x t y he> a ro> 9 ! %ell8 ,:y c y sometimes he> an e*o & sometimes n8 ,if x 7 n = ! fact t s\nd travels r sl[ly1 we %\ld h no e*oes1 = ! s\nd w\ld get back to u practically at ! in/ant we made x4 ,an e*o is m]ely a s\nd1 a s]ies ( air vibrations1 b\nc$ back to u by some?+ at a di/ance4 ,x takes "t = ! vibration :i* we />t to rea* ! wall or cliff t b\nces x back1 & x takes z mu* m "t = ! return+ vibration to rea* our e>s4 ,s y h pl5ty ( "t to f9i% y\r %\t be=e ! s\nd b\nces back aga94 ,! next exp]im5t %[s pretty well h[ ! waves1 or vibrations1 ( s\nd are reflect$2 only 9 ! exp]im5t we use waves ( wat] because !y g m sl[ly & we c wat* !m4 ,,exp]im5t #ei4 ,fill ! long laboratory s9k 7or ! ba?tub at home7 half full ( wat] & />t a wave f "o end4 ,wat* x move along ! side ( ! s9k4 ,notice :at happ5s :5 x rea*es ! o!r end4 ,air waves d ! same ?+2 :5 !y /rike aga9/ a flat surface1 !y b\nce back l a rubb] ball4 ,if y are f> en\gh away f a flat wall or cliff1 & %\t1 ! s\nd 7! air vibrations y />t7 is reflect$ back to y & y he> ! e*o4 ,b if y are close to ! walls1 z 9 an empty room1 ! s\nd rev]b]ates2 x b\nces back & =? f "o wall to ! o!r s rapidly t no di/9ct e*o is he>d1 & !re is m]ely a confusion ( s\nd4 ,illu/ration3 ,,fig4 #ajb4 ,:5 ! wave rea*es ! end ( ! s9k1 x is reflect$ back4 ,s\nd waves are reflect$ 9 ! same way4 ,:5 y drop a pebble 9 wat]1 ! ripples spread 9 all directions4 ,9 ! same way1 :5 y make a s\nd 9 ! op5 air1 ! air waves spread 9 all directions4 ,b :5 y %\t ?r\gh a megaphone ! air waves are all conc5trat$ 9 "o direction & consequ5tly !y are mu* /rong] 9 t direction4 ,h[ev]1 :ile ! megaphone int5sifies s\nd1 ! e*o+ f ! sides ( ! megaphone makes ! s\nd lose "s ( its di/9ctness4 ,,:y ,,x ,,is ,,h>d ,,to ,,und]/& ,a ,,speak] ,,9 ,,an ,,empty ,,hall4 ,a speak] c be he>d mu* m easily 9 a room full ( p ?an 9 an empty hall4 ,! s\nd does n reflect well f ! s(t clo!s ( ! audi5ce & ! unev5 surfaces ( _! bodies1 j z a rubb] ball does n b\nce well 9 s&4 ,s ! s\nd does n rev]b]ate z 9 an empty hall4 ,,application #dc4 ,expla9 :y a c>pet$ room is quiet] ?an "o ) a b>e floor2 :y y %\t ?r\gh y\r h&s :5 y want to be he>d at a di/ance4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bfa4 ,x is h>d] to walk :5 y %uffle y\r feet4 #bfb4 ,! air ov] a lamp *imney1 or ov] a regi/] 9 a furnace-heat$ h\se1 is mov+ upw>d rapidly4 #bfc4 ,! %oot+ ( a gun s\nds mu* l\d] )9 a room ?an x does outdoors4 #bfd4 ,a drum makes a l\d1 cle> s\nd :5 ! tight5$ head is /ruck4 #bfe4 ,! pull ( ! moon causes ! ocean tides4 #bff4 ,s& is sometimes put 9 ! bottom ( vases to keep !m f fall+ ov]4 #bfg4 ,x is difficult to und]/& cle>ly ! words ( "o :o is speak+ 9 an almo/ empty hall4 #bfh4 ,! ridges 9 a wa%bo>d help to clean ! clo!s t are rubb$ ov] !m4 #bfi4 ,"o k9d ( me*anical toy has a heavy lead :eel inside4 ,:5 y />t ?is to :irl+1 ! toy runs = a long "t4 #bgj4 ,if y raise y\r f+] slightly aft] t\*+ ! surface ( wat]1 ! wat] comes up ) y\r f+]4 ,,section #cj4 ,pit*4 ,:at makes ! keys ( a piano give diff]5t s\nds8 ,:y does ! mov+ ( y\r f+]s up & d[n on a viol9 /r+ make x play diff]5t notes8 ,:y is ! :i/le ( a peanut roa/] s %rill1 & :y is ! :i/le ( a boat s deep8 ,did y ev] notice h[ tiresome ! :i/le on a peanut roa/] gets8 ,well1 suppose t :5ev] y spoke y _h to utt] y\r words 9 exactly t pit*2 t e "t a c> came d[n ! /reet its noise 0 l ! :i/le ( ! peanut roa/]1 only l\d]2 t e /ep y took s\nd$ l hitt+ a bell ( ! same pit*2 t :5 y w5t to ! mov+-picture !at] ! or*e/ra play$ only ! "o note2 t :5 any "o sang1 8 voice did n rise & fall2 9 %ort1 t all ! s\nds 9 ! _w 7 9 "o pit*4 ,t is ! way x w\ld be if diff]5t k9ds ( air vibrations did n make diff]5t k9ds ( notes1--if !re 7 no diff]5ces 9 pit*4 ,,pit* ,,due ,,to ,,rapidity ,,( ,,vibration4 ,:5 air vibrations are sl[1--f> ap>t1--! s\nd is l[2 :5 !y are fa/]1 ! s\nd is high]2 :5 !y are v quick inde$1 ! s\nd is v %rill & high4 ,9 v>i\s ways1 z by p talk+ & walk+ & by ! runn+ ( /reet c>s & automobiles1 all sorts ( diff]5t vibrations are />t$1 giv+ u a pleasant v>iety ( high & l[ & m$ium pit*es 9 ! s\nds ( ! _w ar\nd u4 ,an exp]im5t w %[ h[ pit* v>ies & h[ x is regulat$3 ,,exp]im5t #fj4 ,move ! slide ( an adju/able tun+ =k well up f ! end ( ! prongs1 tap "o prong lightly on ! desk1 & li/54 ,move ! slide some:at t[>d ! end ( ! prongs1 & repeat4 ,is a high] or a l[] s\nd produc$ z ! slide %ort5s ! l5g? ( ! prongs8 ,:i/le a l[ note1 !n a high "o4 ,notice :at y d ) y\r lips2 :5 is ! op5+ ! small]8 ,s+ a l[ note1 !n a high "o4 ,:5 are ! cords 9 y\r ?roat loos]8 ,fill a dr9k+ glass half full ( wat]1 & /rike x4 ,n[ p\r half ! wat] out1 & /rike ! glass aga94 ,d y get ! high] s\nd :5 ! column ( wat] is %ort] or :5 x is long]8 ,/ret* a rubb] b& across y\r ?umb & =ef+]4 ,pick ! b& z y make x tight]1 n mak+ x long]1 b pull+ x tight] ) y\r o!r f+]s4 ,does x make a high] or a l[] s\nd z y increase ! tightness8 ,/ret* ! b& f y\r ?umb to y\r little f+] & pick x2 n[ put y\r middle f+] "u ! b& s z to divide x 9 halves1 & pick x aga94 ,does a %ort /r& give a high] or l[] pit* ?an a long /r&8 ,illu/ration3 ,,fig4 #ajc4 ,:5 ! prongs ( ! tun+ =k are made long] or %ort]1 ! pit* ( ! s\nd is *ang$4 ,a viol9i/ tunes 8 viol9 by tight5+ ! /r+s2 ! tight] !y are & ! ?9n] !y are1 ! high] ! note !y give4 ,"s ( ! /r+s are naturally high] ?an o!rs2 ! highe/ is a small]1 f9] /r+ ?an ! l[e/4 ,:5 ! viol9i/ plays1 he %ort5s ! /r+s by hold+ !m d[n ) 8 f+]s1 & ! %ort] he makes !m ! high] ! note4 ,a bass drum is mu* l>g] ?an a high-pit*$ kettl$rum4 ,! pipes ( an organ are long & l>ge = ! l[ notes1 %ort] & small] = ! high ones4 ,9 g5]al1 ! long] or l>g] ! object is t vibrates1 ! sl[] ! rate ( vibration & consequ5tly ! l[] ! pit*4 ,b ! %ort] or f9] ! object is t vibrates1 ! high] ! rate ( vibration & ! high] ! pit*4 ,all musical in/rum5ts conta9 devices :i* c be made to vibrate1--ei!r /r+s or columns ( air1 or o!r ?+s t sw+ to & fro & />t waves 9 ! air4 ,& by tight5+ !m1 or mak+ !m small] or %ort]1 ! pit* c be made high]2 t is1 ! numb] ( vibrations to ea* second c be increas$4 ,,application #dd4 ,expla9 :y a /eamboat :i/le is usually ( mu* l[] pit* ?an is a toy :i/le2 :y a banjo play] moves 8 f+]s t[>d ! drum end ( ! banjo :5 he plays high notes2 :y ! s\nd made by a mosquito is high] 9 pit* ?an t made by a bumblebee4 ,,application #de4 ,a boy _h a banjo giv5 him = ,*ri/mas4 ,he want$ to tune x4 ,to make a /r+ give a high] note1 %\ld he h tight5$ or loos5$ x8 ,or c\ld he h secur$ ! same result by mov+ 8 f+] up & d[n ! /r+ to l5g!n or %ort5 x8 ,,application #df4 ,a man 0 tun+ a piano = a conc]t4 ,! hall 0 cold1 yet he knew x w\ld be w>m at ! "t ( ! conc]t4 ,%\ld he h tun$ ! piano to a high] pit* ?an he want$ x to h on ! conc]t night1 to ! exact pit*1 or to a l[] pit*8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bga4 ,a c[boy :irls 8 lasso ar\nd & ar\nd 8 head be=e he ?r[s x4 #bgb4 ,furnaces are always plac$ 9 ! basem5ts ( build+s1 nev] on top floors4 #bgc4 ,a r slight contraction ( a muscle lifts y\r arm a consid]able di/ance4 #bgd4 ,a play] on a slide trombone *anges ! pit* ( ! notes by l5g!n+ & %ort5+ ! tube :ile he bl[s ?r\gh x4 #bge4 ,ra9 runs (f a t> ro( 9 droplets1 :ile on %+les x soaks 9 some:at & spreads4 #bgf4 ,!re is a sigh+ s\nd z ! w9d bl[s ?r\gh ! bran*es ( trees1 or ?r\gh /ret*$ wires or ropes4 #bgg4 ,sometimes a v viol5t noise breaks ! membrane 9 ! drum ( a p]son's e>4 #bgh4 ,z a /reet c> goes fa/] & fa/]1 ! hum ( its motor is high] & high]4 #bgi4 ,if a /reet is p>tly dry1 ! wet spots %9e m ?an ! dry spots d4 #bhj4 ,molt5 type metal1 :5 p\r$ into a mold1 becomes h>d1 solid type :5 x cools4 ,,*apt] ,,sev5 ,,magnetism ,,& ,,electricity ,,section #ca4 ,magnets2 ! compass4 ,:at makes ! ne$le ( a compass po9t nor?8 ,:at causes ! ,nor!rn ,lights8 ,= _m hundr$s ( ye>s sailors h us$ ! compass to det]m9e directions4 ,dur+ all ?is "t m5 h kn[n t "o po9t ( ! ne$le always sw+s t[>d ! nor? if !re is no iron ne> to pull x "s o!r way1 b until )9 ! pa/ c5tury !y did n "k :y4 ,n[ we h f\nd ! explanation 9 ! fact t ! e>? is a great big magnet4 ,! exp]im5t :i* foll[s w help y to und]/& :y ! e>?'s be+ a magnet %\ld make ! compass ne$le po9t nor? & s\?4 ,,exp]im5t #fa4 ,lay a magnetic compass flat on ! table4 ,notice :i* po9t sw+s to ! nor?4 ,n[ hold a horse%oe magnet1 po9ts d[n1 ov] ! compass4 ,turn ! magnet ar\nd & wat* ! compass ne$le2 see :i* end ( ! magnet attracts ! nor? po9t2 hold t end ( x t[>d ! s\? po9t & note ! effect4 ,hold ! magnet1 ends up1 "u ! table directly bel[ ! compass & turn ! magnet1 wat*+ ! compass ne$le4 ,! e>? is a magnet1 & x acts j z y\r magnet does3 "o end attracts "o po9t ( ! compass1 & ! o!r end attracts ! o!r po9t4 ,t ought to make x cle> :y ! compass po9ts nor?4 ,b h[ is ! compass made8 ,! next exp]im5t w %[ ?is pla9ly4 ,,exp]im5t #fb4 ,take a long %oe/r+ & make a loop 9 "o end ( x4 ,slip ! magnet ?r\gh ! loop & susp5d x1 ends d[n4 ,fa/5 ! %oe/r+ to ! top ( a doorway s t ! magnet c sw+ easily4 ,/eady ! magnet & let x turn until x comes to a re/4 ,m>k ! end t sw+s to ! nor?4 ,turn ?is end ar\nd to ! s\?2 let g & wat* x4 ,place ! magnet ! o!r way ar\nd 9 ! loop s t y c be sure t x is n twi/+ ( ! %oe/r+ t makes ! magnet turn 9 ?is direction4 ,n[ /roke a ne$le sev]al times along "o arm ( ! magnet1 always 9 ! same direction1 z %[n 9 ,figure #aje4 ,hold ! ne$le ov] "s iron fil+s or t\* any bit ( iron or /eel ) x4 ,:at has ! ne$le become8 ,lay x on a c>dbo>d milk-bottle top ( ! flat k9d1 & on t float x 9 ! middle ( a glass or e>!nw>e di% ( wat]4 ,notice :i* end turns nor?4 ,turn ?is end to ! s\? & see :at happ5s4 ,hold y\r magnet1 ends up1 "u ! di%1 & turn ! magnet4 ,:at does ! ne$le d8 ,illu/ration3 ,,fig4 #ajd4 ,! compass ne$le foll[s ! magnet4 ,n[ x %\ld be easy to und]/& :y ! compass po9ts nor?4 ,"o end ( any magnet pulls on "o end ( ano!r magnet & drives ! o!r end away4 ,! e>? is a big magnet4 ,s if y make a magnet & balance x 9 su* a way t x is free to sw+1 ! nor? end ( ! big e>? magnet pulls "o end ( ! little magnet t[>d x & pu%es ! o!r end away4 ,!re=e "o end ( y\r compass always po9ts nor?4 ,,o!r ,,effects ,,( ,,! ,,e>?',s ,,magnetism4 ,ano!r int]e/+ effect ( ! e>?'s be+ a big magnet is to be se5 if y lay a piece ( /eel s t x po9ts nor? & s\?1 & !n p\nd x on "o end4 ,x becomes magnetiz$ j z y\r ne$le became magnetiz$ :5 x 0 rubb$ on ! small magnet4 ,illu/ration3 ,,fig4 #aje4 ,magnetiz+ a ne$le4 ,illu/ration3 ,,fig4 #ajf4 ,a compass made ( a ne$le & a piece ( c>dbo>d4 ,& /ill ano!r effect ( ! e>?'s magnetism is ?is3 ,t9y p>ticles ( electricity1 call$ electrons1 are probably %oot+ ?r\gh space f ! sun4 ,x is believ$ t z !y come ne> ! e>?1 ! magnetism ( ! nor? & s\? pol> regions attracts !m t[>d ! poles1 & t z !y ru% ?r\gh ! ?91 dry upp] air1 !y make x gl[4 ,& ?is is probably :at causes ! ,nor!rn ,lights or ,aurora ,borealis4 ,,:at ,,happ5s ,,:5 ,a ,,ne$le ,,is ,,magnetiz$4 ,! reason t a ne$le becomes magnetic if x is rubb$ ov] a magnet is probably ?is3 ,e molecule ( iron may be an extremely t9y magnet2 if x is1 ea* molecule has a nor? & s\? pole l ! ne$le ( a compass4 ,9 an ord9>y ne$le 7or 9 any unmagnetiz$ piece ( iron or /eel7 ^! molecules w\ld be fac+ e way1 z %[n 9 ,figure #ajg4 ,illu/ration3 ,,fig4 #ajg4 ,diagram ( molecules 9 unmagnetiz$ iron4 ,! nor? & s\? poles ( ! molecules are suppos$ to be po9t+ 9 all directions4 ,illu/ration3 ,,fig4 #ajh4 ,diagram ( magnetiz$ iron4 ,! nor? & s\? poles ( ! molecules are all suppos$ to po9t 9 ! same direction4 ,b :5 a piece ( /eel or iron t is already magnetiz$ is br\ght ne> ! unmagnetiz$ ne$le1 all ! nor? poles ( ! molecules ( ! ne$le are pull$ 9 ! same direction--x is almo/ l comb+ tangl$ hair to /roke a ne$le ov] a magnet4 ,!n ! molecules are arrang$ m z %[n 9 ,figure #ajh4 ,:5 all ! molecules1 ea* ( :i* is a t9y magnet1 pull 9 ! same direction1 !y make a /rong magnet1 & !y magnetize any iron t comes ne> !m j z !y 7 magnetiz$4 ,/eel w /ay magnetiz$ a long "t2 b ord9>y s(t iron loses magnetism almo/ z soon z ano!r magnet is tak5 away f x1--! molecules become all dis>rang$ aga94 ,9 a lat] section y w f9d t :5ev] electricity fl[s ?r\gh a wire t is coil$ ar\nd a piece ( iron1 ! iron becomes magnetiz$ j z :5 x is rubb$ ) a magnet4 ,,application #dg4 ,an explor] lo/ 8 compass4 ,9 cle> wea!r he c\ld tell ! directions by ! sun & />s1 b 9 cl\dy wea!r he 0 badly h&icapp$4 ,he _h ) him a gun1 pl5ty ( ammunition1 a sew+ kit1 a hunt+ knife1 & "s provisions4 ,h[ c\ld he h made a compass8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bha4 ,sn[ turns to wat] 9 ! fir/ w>m wea!r4 #bhb4 ,a p]son's face looks gha/ly by ! gre5i% light ( a m]cury-vapor lamp4 #bhc4 ,if a r$-hot coal is t\*$ ) a cold pok]1 ! coal turns black at ! place t\*$4 #bhd4 ,/]eopticon slides are put 9 upside d[n1 yet ! picture on ! scre5 is "r side up4 #bhe4 ,if ! vocal cords ( y\r ?roat did n vibrate1 y c\ld n talk out l\d4 #bhf4 ,a wat* is sometimes put out ( ord] if x is held ne> a magnet4 #bhg4 ,! wat] w be no high] on ! inside ( a leaky boat ?an x is on ! outside4 #bhh4 ,a bass viol is consid]ably l>g] ?an a viol94 #bhi4 ,%ips t are us$ by m5 te/+ ! e>?'s magnetism c>ry v s5sitive compasses4 ,expla9 :y su* %ips are made entirely ( wood & brass4 #bij4 ,?und] rolls2 t is1 aft] ! fir/ peal !re is a rev]b]at+ s\nd t becomes less & less di/9ct4 ,,section #cb4 ,/atic electricity4 ,:at is electricity8 ,:at makes ?und] & lightn+8 ,:y does ! b>rel or cap ( a f\nta9 p5 pick up small bits ( pap] aft] x has be5 rubb$ on y\r coat sleeve8 ,:y d sp>ks fly f ! fur ( a cat :5 y /roke x 9 ! d>k8 ,! ,greeks1 #bjjj ye>s ago1 knew t !re 0 su* a ?+ z electricity1 & !y us$ to get x by rubb+ amb] ) silk4 ,9 ! pa/ c5tury m5 h le>n$ h[ to make electricity d all sorts ( useful "w3 mak+ boats & c>s & automobiles g1 r++ bells1 furni%+ light1 &1 9 ! telephone & telegraph1 c>ry+ messages4 ,b no "o knew :at electricity really 0 until1 )9 ! la/ #be ye>s1 sci5ti/s f\nd out4 ,,atoms ,,& ,,electrons4 ,:5 we talk$ ab\t molecules1 we said t !y 7 z mu* small] ?an a g]m z a g]m is small] ?an a m\nta94 ,well1 a molecule is made up1 probably1 ( "s ?+s t are mu* small] /ill1--s small t p ?\ght t no?+ c\ld be small]4 ,^? un?9kably t9y ?+s are call$ atoms2 y w he> m ab\t !m :5 y come to ! p>ts ( ?is book t tell ab\t *emi/ry4 ,b if y took ! smalle/ atom 9 ! _w & divid$ x into #agjj pieces1 ea* "o ( ^! w\ld be ab\t ! size ( a piece ( electricity4 ,electricity is made up ( ! t9ie/ ?+s kn[n to man--?+s s small t nobody really c ?9k ( _! smallness4 ,^! little pieces ( electricity are call$ electrons1 & = all _! smallness1 sci5ti/s h be5 able to f9d out a good deal ab\t !m4 ,!y h manag$ to get "o electron all by itself on a droplet ( oil & !y h se5 h[ x made ! oil behave4 ,( c\rse !y c\ld n see ! electron1 b !y c\ld tell f v>i\s exp]im5ts t !y _h j "o4 ,sci5ti/s "k h[ _m trillions ( electrons fl[ ?r\gh an inc&esc5t electric lamp 9 a second & h[ _m quadrillions ( !m x w\ld take to weigh z mu* z a fea!r4 ,!y "k :at ! electrons d :5 !y move1 h[ fa/ !y c move1 & :at sub/ances let electrons move ?r\gh !m easily & :at sub/ances hold !m back2 & !y "k p]fectly well h[ to set !m 9 motion4 ,h[ ! sci5ti/s came to "k all ^! ?+s y w le>n 9 ! /udy ( physics2 x is a long /ory4 ,b y c f9d out "s ?+s ab\t electrons y\rself4 ,! fir/ exp]im5t is a simple "o su* z ! ,greeks us$ to d ) amb]4 ,,exp]im5t #fc4 ,rub a h>d rubb] comb on a piece ( wool5 clo?4 ,! sleeve ( a wool5 coat or sweat] w d4 ,rub ! comb quickly 9 ! same direction sev]al times4 ,n[ hold x ov] "s small bits ( pap] or sawdu/4 ,:at does x d to !m8 ,hold x ov] "s "o's hair4 ,! re/ ( ?is exp]im5t w "w well only on cool1 cle> days4 ,rub ! comb aga91 a doz5 or m times 9 quick succession4 ,n[ t\* x g5tly to ! lobe ( y\r e>4 ,d y he> ! snap z ! small sp>k jumps f ! comb to y\r e>8 ,pull a dry hair out ( y\r head & hold x by "o end4 ,*>ge y\r comb by rubb+ x aga91 & br+ x ne> ! loose end ( ! hair4 ,if ! end ( ! hair cl+s to ! comb at fir/1 leave x cl++ until x flies (f4 ,n[ try to t\* ! hair ) ! comb4 ,next1 p9* ! end ( ! hair betwe5 y\r ?umb & f+] & aga9 br+ ! *>g$ comb ne> x4 ,is ! hair attract$ or repell$8 ,aft] t\*+ ! comb :at does x d8 ,y c get ! same effects by rubb+ glass or amb] on silk4 ,illu/ration3 ,,fig4 #aji4 ,:5 ! comb is rubb$ on ! coat1 x becomes *>g$ ) electricity4 ,,objects ,,negatively ,,& ,,positively ,,*>g$ ,,) ,,electricity4 ,!re are probably electrons 9 ev]y?+4 ,b :5 !re is j ! usual numb] ( electrons 9 an object1 x acts 9 an ord9>y way & we say t x is n *>g$ ) electricity4 ,if !re are m ?an ! usual numb] ( electrons on an object1 h[ev]1 we say t x is negatively *>g$1 or t x has a negative *>ge ( electricity on x4 ,b if !re are few] electrons ?an usual 9 an object1 we say t x has a positive *>ge ( electricity on x1 or t x is positively *>g$4 ,y might expect a negative *>ge to indicate few] electrons ?an usual1 n m4 ,b p call$ ! *>ge negative long be=e !y knew any?+ ab\t electrons2 & x is easi] to keep ! old "n ?an to *ange all ! books t h be5 writt5 ab\t electricity4 ,s we /ill call a *>ge negative :5 !re are unusually _m electrons1 & we call x positive :5 !re are unusually few4 ,a negative *>ge means t m electrons are pres5t ?an usual4 ,a positive *>ge means t few] electrons are pres5t ?an usual4 ,illu/ration3 ,,fig4 #aaj4 ,! *>g$ comb picks up pieces ( pap]4 ,be=e y rubb$ y\r comb on wool1 nei!r ! comb nor ! wool 0 *>g$2 bo? _h j ! usual numb] ( electrons4 ,b :5 y rubb$ !m toge!r1 y rubb$ "s ( ! electrons (f ! wool on to ! comb4 ,!n ! comb _h a negative *>ge2 t is1 x _h too _m electrons--too _m little p>ticles ( electricity4 ,:5 y br\ght ! comb ne> ! hair1 ! hair _h few] electrons ?an ! comb4 ,:5ev] "o object has m electrons on x ?an ano!r1 ! two objects are pull$ t[>d ea* o!r2 s !re 0 an attraction betwe5 ! comb & ! hair1 & ! hair came ov] to ! comb4 ,z soon z x t\*$ ! comb1 "s ( ! extra electrons jump$ f ! comb to ! hair4 ,! electrons c\ld n get (f ! hair easily1 s !y /ay$ !re4 ,electrons repel ea* o!r--drive ea* o!r away4 ,s :5 y _h a numb] ( electrons on ! end ( ! comb & a numb] on ! end ( ! hair1 !y pu%$ ea* o!r away1 & ! hair flew f ! comb4 ,b :5 y p9*$ ! hair1 ! electrons c\ld get (f x to y\r moi/ h&1 :i* lets electricity ?r\gh x fairly easily4 ,!n ! comb _h extra electrons on x & ! hair did n2 s ! comb pull$ ! hair ov] t[>d x aga94 ,:5 y br\ght ! *>g$ comb ne> y\r e>1 "s ( ! electrons on ! comb pu%$ ! o!rs (f to y\r e>1 & y he>d !m snap z !y ru%$ ?r\gh ! air1 mak+ x vibrate4 ,,h[ ,,lightn+ ,,& ,,?und] ,,are ,,caus$4 ,9 ?und]/orms ! /rong curr5ts ( ris+ air bl[ "s ( ! =m+ ra9drops 9 ! cl\ds into bits ( spray4 ,! t9i] droplets get m ?an _! %>e ( electrons :5 ?is happ5s & are c>ri$ on up to high] cl\ds4 ,9 ?is way cl\ds become *>g$ ) electricity4 ,"o cl\d has on x _m m electrons ?an ano!r cl\d t is made1 p]haps1 ( l[]1 l>g] droplets4 ,! electricity leaps f ! cl\d t has ! great] numb] ( electrons to ! cl\d t has ! less numb]1 or x leaps f ! heavily *>g$ cl\d d[n to a tree or h\se or ! gr\nd4 ,y see ! electricity leap & call x lightn+4 ,mu* m leaps1 h[ev]1 ?an leap$ f ! comb to y\r e>1 & s x makes a v mu* l\d] snap4 ,! snap is caus$ 9 ?is way3 ,z ! electric sp>k leaps ?r\gh ! air1 x leaves an empty space or vacuum imm$iately beh9d x4 ,! air f all sides ru%es into ! vacuum & collides !re2 !n x b\nces back4 ,?is aga9 leaves a p>tial vacuum2 s ! air ru%es 9 once m1 com+ f all sides at once1 & aga9 b\nces back4 ,?is />ts ! air vibrations :i* we call s\nd4 ,!n ! s\nd is e*o$ f cl\d to cl\d & f ! cl\ds to ! e>? & back aga91 & we call x ?und]4 ,! electricity y h be5 read+ ab\t & exp]im5t+ ) 9 ?is section is call$ /atic electricity4 ,/atic means /&+ /ill4 ,! electricity y rubb$ up to ! surface ( ! comb or glass /ay$ /ill until x jump$ to ! bit ( pap] or hair2 !n x /ay$ /ill on t4 ,?is 0 ! only k9d ( electricity mo/ p knew any?+ ab\t until ! n9ete5? c5tury2 & x is n ( any great use4 ,electricity mu/ be fl[+ ?r\gh ?+s to d "w4 ,t is :y p c\ld n inv5t electric c>s & electric lights & telephones be=e !y knew h[ to make electricity fl[ /eadily r ?an j to /& /ill on "o ?+ until x jump$ across to ano!r & /ood !re4 ,9 ! next *apt] we %all take up ! ways 9 :i* electrons are made to fl[ & to d "w4 ,,application #dh4 ,expla9 :y ! /rok+ ( a cat's back w sometimes cause sp>ks & make ! cat's hairs /& ap>t2 :y comb+ sometimes makes y\r hairs fly ap>t4 ,bo? ( ^! effects are be/ secur$ on a dry day1 because on a damp day ! wat] p>ticles 9 ! air w let ! electrons pass to !m z fa/ z !y are rubb$ up to ! surface ( ! hair4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #bia4 ,if y %uffle y\r feet on a c>pet 9 cle>1 cold wea!r & !n t\* a p]son's nose or e>1 a slight sp>k passes f y\r f+] & /+s him4 #bib4 ,if y /ay out 9 ! cold long1 y get *ill$ ?r\gh4 #bic4 ,! air & e>? 9 a gre5h\se are w>m$ by ! sun ?r\gh ! glass ev5 :5 x is cold outside & :5 ! glass itself rema9s cold4 #bid4 ,:5 y hold a blade ( grass taut betwe5 y\r ?umbs & bl[ on x1 y get a noise4 #bie4 ,%ad[s are usually black4 #bif4 ,"s wom5 keep magnets ) :i* to f9d lo/ ne$les4 #big4 ,y c grasp objects mu* m firmly ) pli]s ?an ) y\r f+]s4 #bih4 ,if ! glass 9 a mirror is unev51 ! image ( y\r face is unnatural4 #bii4 ,a sweat] cl+s close to y\r body4 #cjj4 ,kit*5s1 ba?rooms1 & hospitals %\ld h pa9t$ walls4 ,,*apt] ,,eight ,,electricity ,,section #cc4 ,mak+ electricity fl[4 ,:at causes a batt]y to produce electricity8 ,:at makes electricity come into our h\ses8 ,! k9d ( electricity y get f rubb+ 7friction7 is n ( mu* practical use1 y rememb]4 ,m5 _h to f9d a way to get a /eady curr5t ( electricity be=e !y c\ld make electricity d any "w = !m4 ,! diff]5ce betwe5 /atic electricity--:5 x leaps f "o ?+ to ano!r--& fl[+ electricity is a good deal l ! diff]5ce betwe5 a %ort %[] ( ra9 & a riv]4 ,bo? ra9 & riv] are wat]1 & ! wat] ( ea* is mov+ f "o place to ano!r2 b y _c get ! ra9drops to make any really practical ma*9e g1 :ile ! riv]s c d real "w by turn+ ! :eels 9 factories & mills4 ,)9 ! pa/ c5tury two devices = mak+ electricity fl[ & d "w h be5 p]fect$3 ,"o ( ^! is ! electric batt]y2 ! o!r is ! dynamo4 ,,! ,,electric ,,batt]y4 ,a batt]y consi/s ( two pieces ( diff]5t k9ds ( metal1 or a metal & "s c>bon1 9 a *emical solution4 ,if y hang a piece ( z9c & a c>bon1 su* z comes f an arc light1 9 "s wat]1 & !n dissolve sal ammoniac 9 ! wat]1 y w h a batt]y4 ,"s ( ! molecules ( ! sal ammoniac divide into two p>ts :5 ! sal ammoniac gets into ! wat]1 & ! molecules cont9ue to divide z long z ! batt]y is 9 use or until x we>s out4 ,"o "p ( ea* molecule has an unusually l>ge numb] ( electrons2 ! o!r "p has unusually few4 ,! p>ts ) unusually l>ge numb]s ( electrons ga!r ar\nd ! z9c2 s ! z9c is negatively *>g$1--x has m ?an ! ord9>y numb] ( electrons4 ,! "p ( ! sal ammoniac ) unusually few electrons goes ov] to ! c>bon2 s ! c>bon is positively *>g$1--x has few] ?an ! ord9>y numb] ( electrons4 ,,mak+ ,,! ,,curr5t ,,fl[4 ,n[ if we c make "s k9d ( bridge betwe5 ! c>bon & ! z9c1 ! electrons w fl[ f ! place :]e !re are _m to ! place :]e !re are few4 ,electrons c fl[ ?r\gh copp] wire v easily4 ,s if we fa/5 "o end ( ! copp] wire to ! c>bon & ! o!r end to ! z9c1 ! electrons w fl[ f ! z9c to ! c>bon z long z !re are m electrons on ! z9c2 t is1 until ! batt]y we>s out4 ,!re=e we h a /eady fl[ ( electricity ?r\gh ! wire4 ,:ile ! electricity is fl[+ f "o pole to ! o!r1 we c make x d "w4 ,,exp]im5t #fd4 ,set up two or ?ree ,samson cells4 ,!y consi/ ( a glass j>1 an op5 z9c cyl9d]1 & a small] c>bon cyl9d]4 ,dissolve a little ov] half a cup ( sal ammoniac 9 wat] & put x into ! glass j>2 !n fill ! j> ) wat] up to ! l9e t is m>k$ on x4 ,put ! c>bon & z9c :i* are atta*$ to ! black j> cov] into ! j>4 ,be c>eful n to let ! c>bon t\* ! z9c4 ,"o ( ^! cells w probably n be /rong en\gh to r+ a doorbell = y2 s connect two or ?ree toge!r 9 s]ies z foll[s3 ,fa/5 a piece ( copp] wire f ! c>bon ( ! fir/ cell to ! z9c ( ! second4 ,if y h ?ree cells1 fa/5 ano!r piece ( wire f ! c>bon ( ! second cell to ! z9c ( ! ?ird1 z %[n 9 ,figure #aaa4 ,fa/5 "o end ( a copp] wire to ! z9c ( ! fir/ cell & ! o!r end ( ?is wire to "o b9d+ po/ ( an electric bell4 ,fa/5 "o end ( ano!r piece ( copp] wire to ! c>bon ( ! ?ird cell1 if y h ?ree1 & t\* ! o!r end ( ?is wire to ! free b9d+ po/ ( ! electric bell4 ,if y h ev]y?+ connect$ rightly1 ! bell %\ld r+4 ,illu/ration3 ,,fig4 #aaa4 ,a wet batt]y ( ?ree cells connect$ to r+ a bell4 ,,diff]5t ,,k9ds ,,( ,,batt]ies4 ,!re are _m diff]5t k9ds ( batt]ies4 ,! "o y h j made is a simple "o frequ5tly us$ = doorbells4 ,o!r batt]ies are m complicat$4 ,"s are made ) copp] & z9c 9 a solution ( copp] sulfate2 "s1 ev51 are made by lett+ electricity f a dynamo run ?r\gh a solution f "o lead plate to ano!r until a *emical sub/ance is /or$ on "o ( !m2 !n1 :5 ! two lead plates are connect$ by a wire1 ! electrons run f "o to ! o!r4 ,?is k9d ( batt]y is call$ a /orage batt]y1 & x is mu* us$ 9 subm>9es & automobiles4 ,illu/ration3 ,,fig4 #aab4 ,a batt]y ( ?ree dry cells4 ,b all ! diff]5t batt]ies "w on ! same g5]al pr9ciple3 ,a *emical solution divides into two p>ts1 "o ) _m electrons & ! o!r ) a less numb]4 ,"o "p ( ! solution ga!rs on "o pole 7piece ( metal 9 ! solution7 & *>ges x positively2 ! o!r "p ga!rs on ! o!r pole & *>ges x negatively4 ,!n ! electricity fl[s f "o pole to ! o!r4 ,,positive ,,& ,,negative ,,poles4 ,be=e p knew any?+ ab\t electrons1 !y knew t electricity fl[$ f "o pole ( a batt]y to ! o!r4 ,b !y always said t x fl[$ f ! c>bon to ! z9c2 & !y call$ ! c>bon ! positive pole & ! z9c ! negative4 ,al?\gh we n[ "k t ! electrons fl[ f ! z9c to ! c>bon1 x is mu* m conv5i5t to use ! old way ( speak+1 z 0 expla9$ on page #aii4 ,practically1 x makes no diff]5ce :i* way ! electrons are go+ z long z a curr5t ( electricity is fl[+ ?r\gh ! wire f "o pole ( ! batt]y to ! o!r pole4 ,s e "o speaks ( electricity z fl[+ f ! positive pole ( a batt]y 7usually ! c>bon or copp]7 to ! negative pole 7usually ! z9c71 al?\gh ! electrons actually move 9 ! o!r direction4 ,illu/ration3 ,,fig4 #aac4 ,a /orage batt]y4 ,batt]ies make en\gh electricity fl[ to d a good deal ( "w4 ,b !y are r exp5sive1 & x takes a great _m to give a fl[ ( electricity suffici5t = really heavy "w1 su* z runn+ /reet c>s or light+ a city4 ,=tunately !re is ano!r way ( gett+ l>ge am\nts ( electricity to fl[4 ,?is is by means ( dynamos4 ,,h[ ,a ,,dynamo ,,makes ,a ,,curr5t ,,fl[4 ,to und]/& a dynamo1 y mu/ fir/ realize t !re are c\ntless electrons 9 ! _w--p]haps all ?+s are made entirely ( !m4 ,b y rememb] t :5 we want to get ^! electrons to d "w we mu/ make !m fl[4 ,?is c be done by sp9n+ a loop ( wire betwe5 ! poles ( a magnet4 ,:5ev] a loop ( wire is turn$ betwe5 ! two poles ( a magnet1 ! magnetism pu%es ! electrons t are already 9 ! wire ar\nd & ar\nd ! loop4 ,z long z we keep ! loop sp9n+1 a curr5t ( electricity fl[s4 ,illu/ration3 ,,fig4 #aad4 ,sp9n+ loops ( wire betwe5 ! poles ( a magnet causes a curr5t ( electricity to fl[ ?r\gh ! wire4 ,if only "o loop ( wire is spun betwe5 ! poles ( a magnet1 ! curr5t is v feeble4 ,if y loop ! wire ar\nd twice1 z %[n 9 ,figure #aad1 ! magnet acts on twice z mu* ( ! wire at ! same "t2 s ! curr5t is /rong]4 ,if a v long piece ( wire is us$ & is loop$ ar\nd _m times1 & ! :ole coil is spun rapidly betwe5 ! poles ( a p[]ful magnet1 myriads ( ! electrons 9 ! wire ru% ar\nd & ar\nd ! loops--a p[]ful curr5t ( electricity fl[s ?r\gh ! wire4 ,illu/ration3 ,,fig4 #aae4 ,! m loops !re are1 ! /rong] ! curr5t4 ,n[ suppose y br+ "o loop ( ! long wire out1 z %[n 9 ,figure #aae1 & suppose y sp9 ! re/ ( ! loops betwe5 ! poles ( ! magnet4 ,!n1 to fl[ ?r\gh ! loops by ! magnet ! electricity w h to g cle> out ?r\gh ! long loop & back aga94 ,:ile x is fl[+ ?r\gh ?is long loop1 we c make x "w4 ,we c cut ! long loop & atta* "o brok5 end to "o "p ( an electric lamp & ! o!r end to ! o!r "p1 s t ! electricity has to fl[ ?r\gh ! lamp 9 ord] to get back to ! sp9n+ coil ( wire1 z %[n 9 ,figure #aaf4 ,su* an arrangem5t z ?is is really an extremely simple dynamo4 ,illu/ration3 ,,fig4 #aaf4 ,if ! electricity passes ?r\gh a lamp on its way ar\nd ! circuit ! filam5t ( ! lamp gl[s4 ,illu/ration3 ,,fig4 #aag4 ,a dynamo 9 an electric light plant4 ,y c\ld make a dynamo t w\ld actually "w1 by arrang+ su* an app>atus s t ! coil w\ld sp9 betwe5 ! poles ( ! magnet4 ,b ( c\rse ! big comm]cial dynamos are v mu* m complicat$ 9 _! con/ruction4 ,figure #aaf %[s only ! g5]al pr9ciple on :i* !y "w4 ,! ma9 po9t to note is t by sp9n+ a coil ( wire betwe5 ! poles ( a magnet1 y c make electricity fl[ rapidly ?r\gh ! wire4 ,& x is 9 ?is way t mo/ ( ! electricity we use is made4 ,! p[] sp9n+ ! coil ( wire is sometimes /eam1 & sometimes gasol9e or di/illate2 & wat] p[] is v (t5 us$4 ,a l>ge am\nt ( our electricity comes f places :]e !re are wat]falls4 ,niag>a1 = in/ance1 turns great dynamos & g5]ates an enorm\s am\nt ( electricity4 ,,:y ,,_m ,,automobiles ,,h ,,to ,,be ,,crank$4 ,9 an automobile1 ! magneto is a little dynamo t makes ! sp>ks :i* explode ! gasol9e4 ,:ile ! automobile is go+ ! eng9e sp9s ! coil ( wire betwe5 ! magnets1 b at />t+ y h to sp9 ! coil y\rself2 & do+ t is call$ crank+ ! automobile4 ,self-/>t]s h a batt]y & motor to sp9 ! coil = y until ! eng9e beg9s to g2 !n ! eng9e turns ! coil ( ! magneto4 ,,h[ ,,old-,,fa%ion$ ,,telephones ,,are ,,rung4 ,! old-fa%ion$ telephones1 /ill (t5 us$ 9 ! c\ntry1 h little cranks t y turn to r+ = c5tral4 ,! crank turns a coil ( wire betwe5 ! poles ( ! magnet & g5]ates ! electricity = r++ ! bell4 ,^! little dynamos1 l ^? 9 automobiles1 are usually call$ magnetos4 ,illu/ration3 ,,fig4 #aah4 ,! magneto 9 an automobile is a small dynamo4 ,,alt]nat+ ,,curr5t4 ,= ! sake ( simplicity & conv5i5ce we speak ( electricity z always fl[+ 9 ?r\gh "o wire & out ?r\gh ! o!r4 ,) batt]ies ?is is actually ! case4 ,x is also ! case :]e p h :at is call$ direct-curr5t 7d4 c47 electricity4 ,b x is easi] to raise & l[] ! voltage 7pressure7 ( ! curr5t if in/ead ( be+ direct x is alt]nat+2 t is1 if = "o in/ant ! electricity fl[s 9 ?r\gh "o wire & out ?r\gh ! o!r1 ! next in/ant fl[+ ! opposite way1 !n ! fir/ way aga91 & s on4 ,?is k9d ( curr5t is call$ alt]nat+ curr5t 7a4 c471 because ! curr5t alt]nates1 com+ 9 ! upp] wire & out ( ! l[] = a fraction ( a second2 !n com+ 9 ! l[] & out ( ! upp] = ! next fraction ( a second2 !n com+ 9 ! upp] aga9 & out ( ! l[] = a fraction ( a second2 & s on1 back & =?1 all ! "t4 ,= heat+ & light+1 ?is alt]nat+ curr5t is j z good z ! direct curr5t1 & x is probably :at y h 9 y\r own home4 ,= *>g+ /orage batt]ies & mak+ electromagnets1 sep>at+ wat] into two gases1 & = runn+ c]ta9 k9ds ( motors1 h[ev]1 ! direct curr5t is necess>y4 ,f9d out :e!r ! curr5t 9 y\r laboratory is direct or alt]nat+4 ,,application #di4 ,expla9 :y we ne$ fuel or wat] to g5]ate l>ge curr5ts ( electricity2 h[ we c get small am\nts ( electricity to fl[ )\t us+ dynamos2 :y automobiles mu/ be crank$ unless !y h batt]ies to />t !m4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cja4 ,mexican wat] j>s are made ( por\s clay2 ! wat] t seeps ?r\gh keeps ! wat] inside cool4 #cjb4 ,:5 y crank an automobile1 electricity is g5]at$4 #cjc4 ,potatoes w n cook any m quickly 9 wat] t is boil+ viol5tly ?an 9 wat] t is boil+ g5tly4 #cjd4 ,:5 y bru% y\r hair on a w9t] morn+1 x sometimes /&s up & flies ap>t m & m z y cont9ue to bru% x4 #cje4 ,y _c see a p]son cle>ly ?r\gh a gr\nd-glass w9d[1 al?\gh x lets mo/ ( ! light ?r\gh4 #cjf4 ,!re is a lay] ( co>se1 light-color$ gravel ov] ! t> on ro(s1 to keep ! t> f melt+4 #cjg4 ,x is v easy to slip on a well-wax$ h>dwood floor4 #cjh4 ,if y h a silv] fill+ 9 "o ( y\r tee? & y t\* ! fill+ ) a =k or spoon1 y get a slight %ock4 #cji4 ,y c %ake a ?+ d[n into a bottle :5 x w n slip d[n by itself4 #caj4 ,if y rub a ne$le across "o pole ( a magnet ?ree or f\r times 9 ! same direction1 !n float x on a cork 9 wat] "o end ( ! ne$le w po9t nor?4 ,,section #cd4 ,conduction ( electricity4 ,h[ does electricity travel8 ,:y d y get a %ock if y\r h&s are wet :5 y t\* a live wire8 ,if y 7 to use a piece ( /r+ in/ead ( a copp] wire to g f "o pole ( a batt]y to ano!r or to sp9 betwe5 ! poles ( ! magnet ( ! dynamo1 y c\ld get no fl[ ( electricity to speak (4 ,electrons d n fl[ ?r\gh /r+ easily1 b !y fl[ ?r\gh a copp] wire v easily4 ,any?+ t c>ries1 or conducts1 electricity well is call$ a good conductor4 ,any?+ t c>ries x poorly is call$ a poor conductor4 ,any?+ t all[s practically no electricity to pass ?r\gh x is call$ an insulator4 ,,exp]im5t #fe4e ,turn on an electric lamp4 ,turn x (f by op5+ ! knife swit*4 ,cov] ! blade ( ! knife swit* ) a fold ( pap] & close x4 ,w ! lamp gl[8 ,try a fold ( dry clo?2 a fold ( ! same clo? wet4 ,connect ! blade to ! slot ) a piece ( iron2 ) a piece ( glass2 ) porcela92 ) rubb]2 ) dry wood2 ) wood t is soak+ wet2 ) a co94 ,:i* ( ^! are good conductors ( electricity8 ,:i* c\ld be us$ z insulators8 ,footnote #e3 ,read footnote1 page #bbf1 be=e do+ ?is exp]im5t4 ,illu/ration3 ,,fig4 #aai4 ,electricity fl[s ?r\gh ! co94 ,,h[ ,,y ,,c ,,get ,,an ,,electrical ,,%ock4 ,a p]son's body is n a v good conductor ( electricity1 b w conduct x some:at4 ,:5 electricity goes ?r\gh y\r body1 y get a %ock4 ,! %ock f ! ord9>y curr5t ( electricity1 #aaj volts1 is n en\gh to injure y at all2 9 fact1 if y 7 /&+ on dry wood1 x w\ld be safe1 al?\gh y w\ld get a slight %ock1 to connect ! blade ( a knife swit* to ! slot ( ! swit*1 ?r\gh y\r h& or body4 ,y\r body w\ld n all[ en\gh curr5t to pass ?r\gh x to light ! lamp4 ,/rong] curr5ts1 l ^? ( p[] l9es & ev5 trolley wires1 are extremely dang]\s4 ,all ! electric wires ent]+ y\r h\se are made ( copp]4 ,!y are all cov]$ ) clo? & rubb] & are fa/5$ ) glass or porcela9 knobs4 ,! reason is simple3 ,copp] & practically all o!r metals are v good conductors ( electricity2 t is1 !y all[ electricity to pass ?r\gh !m v easily4 ,clo?1 rubb]1 glass1 & porcela9 are v poor conductors1 & !y are !re=e us$ z insulators1--to keep ! electricity f go+ :]e y d n want x to g4 ,illu/ration3 ,,fig4 #abj4 ,w electricity g ?r\gh ! glass8 ,,exp]im5t #ff4 ,to ea* b9d+ po/ ( an electric bell fa/5 a piece ( insulat$ copp] wire ) b>e ends & at lea/ #d feet long4 ,connect ! free end ( "o ( ^! wires ) "o pole ( a batt]y1 us+ a regul> laboratory batt]y or "o y made y\rself4 ,atta* "o end ( ano!r piece ( wire a foot or s long1 ) b>e ends1 to ! o!r pole ( ! batt]y4 ,t\* ! free end ( ?is %ort wire to ! free end ( ! long wire1 z %[n 9 ,figure #abj4 ,does ! bell r+8 ,if x does n1 some?+ is wrong ) ! connection or ) ! batt]y2 fix !m s t ! bell w r+4 ,n[ leave a gap ( ab\t an in* betwe5 ! free end ( ! long wire & ! free end ( ! %ort wire4 ,try mak+ ! electricity fl[ f ! %ort wire into ! long "o ?r\gh a numb] ( diff]5t ?+s1 su* z /r+1 a key1 a knife1 a piece ( glass tub+1 wet clo?1 dry clo?1 rubb]1 pap]1 a nail1 a di% ( m]cury 7dip ! ends ( ! wire into ! di% s t !y bo? t\* ! m]cury at ! same "t71 a di% ( wat]1 a /one1 a pail1 a p91 & any?+ else t y may l to try4 ,illu/ration3 ,,fig4 #aba4 ,electrical app>atus3 ,a1 plug fuse2 ,b1 c>tridge fuse2 ,c1 knife swit*2 ,d1 snap swit*2 ,e1 socket ) nail plug 9 x2 ,f1 fuse gap2 ,g1 flu% swit*2 ,h1 lamp socket2 ,i1 ,j1 ,k1 resi/ance wire4 ,ea* ?+ t makes ! bell r+ is a good conductor4 ,ea* "o t w n make x r+ is a poor conductor or an insulator4 ,make a li/ ( ! ?+s y h tri$2 9 "o column note ! good conductors1 & 9 ano!r column note ! insulators & poor conductors4 ,! wat] & wet clo? did n r+ ! bell1 b ?is is because ! pressure or voltage ( ! electricity 9 ! batt]ies is n v high4 ,9 deal+ ) high-p[] wires x is mu* saf] to consid] wat]1 or any?+ wet1 z a pretty good conductor ( electricity4 ,absolutely pure1 di/ill$ wat] is an extremely poor conductor2 b mo/ wat] has en\gh m9]als dissolv$ 9 x to make x conduct electricity fairly well4 ,9 y\r li/ y _h bett] put wat] & wet ?+s 9 ! column ) ! good conductors4 ,,application #ej4 ,robb]s _h cut ! telegraph l9e betwe5 two railroad /ations 7,fig4 #abb74 ,! brok5 ends ( ! wire fell to ! gr\nd1 a numb] ( feet ap>t4 ,a f>m] caught sight ( ! m5 spe$+ away 9 an automobile & he saw ! cut wires on ! gr\nd4 ,he guess$ t !y _h "s evil purpose & decid$ to repair ! damage4 ,he c\ld n br+ ! two ends ( ! wire toge!r4 ,he ran to 8 b>n & f\nd ! foll[+ ?+s !re3 ,a ball ( cord1 a pickax1 a cr[b>1 "s h>ness1 a wood5 wagon tongue1 a :ip1 a piece ( iron wire ar\nd a bale ( hay 7! wire 0 n long en\gh to /ret* ! :ole di/ance betwe5 ! two ends ( ! telegraph wire1 ev5 if y ?9k he might h us$ x to pat* ! gap71 a b>rel ) f\r iron hoops1 & a rope4 ,:i* ( ^! ?+s c\ld he h made use ( 9 connect+ ! brok5 ends ( ! telegraph wire8 ,illu/ration3 ,,fig4 #abb4 ,:i* %\ld he *oose to connect ! brok5 wires8 ,,application #ea4 ,a man 0 ab\t to put 9 a new socket = an electric lamp 9 8 home4 ,he did n want to turn (f ! curr5t = ! :ole h\se1 z x 0 night & !re 0 no gas to furni% light :ile he work$4 ,i've he>d t if y keep y\r h&s wet :ile y "w1 ! film ( wat] on !m w keep y f gett+ a %ock1 8 wife said4 ,don't y wet y\r h&s1 ,fa!r1 said 8 #ab-ye>-old boy2 keep !m dry1 & h&le ! wires ) y\r pli]s1 s t y won't h to t\* x4 ,i advise y to put on y\r canvas gloves :ile y "w2 !n y c't get a %ock1 add$ ano!r memb] ( ! family4 ,t's a good idea1 said ! wife1 b wet ! gloves1 !n y w h ! d\ble protection ( ! wat] & ! clo?4 ,! man laugh$ & w5t to "w on ! socket4 ,he did n get a %ock4 ,:i* advice1 if any1 d y ?9k he foll[$8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #caa4 ,a r$ po/age /amp looks gre5i% gray 9 ! gre5 light ( a m]cury-vapor lamp4 #cab4 ,cracks are left betwe5 sections ( ! roadb$ 9 cem5t auto highways4 #cac4 ,electricity goes up a m\nta9 ?r\gh a wire4 #cad4 ,x is impossible to /& sidewise aga9/ a wall on "o foot1 :5 t foot t\*es ! wall4 #cae4 ,a *>g$ /orage batt]y w run an electric automobile4 #caf4 ,an empty h\se is noisi] to walk 9 & talk 9 ?an is a furni%$ "o4 #cag4 ,lightn+ rods are made ( metal4 #cah4 ,x is h>d] to hold a fry+ pan by ! end ( ! h&le ?an by "p ( ! h&le close to ! pan4 #cai4 ,diamonds fla% _m colors4 #cbj4 ,9 swimm+1 if y h hold ( a fa/5$ rope & try to pull x t[>d y1 y g t[>d x4 ,,section #ce4 ,complete circuits4 ,:y does a doorbell r+ :5 y pu% a button8 ,:y is x t :5 y t\* "o electric wire y feel no %ock1 :ile if y t\* two wires y sometimes get a %ock8 ,:5 a wire is brok5 9 an electric light1 :y does x n light8 ,suppose y h "s wat] 9 an op5 circul> tr\gh l ! "o %[n 9 ,figure #abc4 ,!n suppose y h a paddle & keep pu%+ ! wat] to y\r "r f "o po9t4 ,! wat] y pu% pu%es ! wat] next to x1 t pu%es ! wat] next to x1 & s on all ar\nd ! tr\gh until ! wat] j beh9d y\r paddle pu%es 9 t[>d ! paddle2 ! wat] goes ar\nd & ar\nd ! tr\gh 9 a complete circuit4 ,!re nev] is too mu* wat] 9 "o place2 y nev] run out ( wat]4 ,b !n suppose a p>tition is put across ! tr\gh some:]e along ! circuit4 ,:5 ! wat] rea*es t1 x _c pass2 x has no place to fl[ to1 & ! curr5t ( wat] /ops4 ,,! ,,electric ,,circuit4 ,! fl[ ( electricity 9 an electric circuit may be comp>$ to ! fl[ ( ! wat] 9 ! tank we h be5 imag9+4 ,! long loop ( wire ext5d+ out f ! dynamo to y\r h\se & back aga9 corresponds to ! tank4 ,! electricity corresponds to ! wat]4 ,y\r dynamo pu%es ! electricity ar\nd & ar\nd ! circuit1 z ! paddle pu%es ! wat]4 ,b let "s "o break ! circuit by putt+ a p>tition betwe5 two p>ts ( x1 & ! electricity imm$iately /ops fl[+4 ,"o ( ! mo/ effective p>titions we c put into an electric circuit is a gap ( air4 ,x is v difficult = any electricity to fl[ ?r\gh ! air2 s if we simply cut ! wire 9 two1 electricity c no long] fl[ f "o "p to ! o!r1 & ! curr5t is brok54 ,illu/ration3 ,,fig4 #abc4 ,electricity fl[s ar\nd a complet$ circuit some:at z wat] might be made to fl[ ar\nd ?is tr\gh4 ,,break+ ,,& ,,mak+ ,,! ,,circuit4 ,! mo/ conv5i5t way to put an air p>tition into an electric circuit & s to break x1 or to close ! circuit aga9 s x w be complete1 is to use a swit*4 ,,exp]im5t #fg4 ,9 ! laboratory1 exam9e ! ?ree diff]5t k9ds ( swit*es :]e ! electricity fl[s into ! lamp & resi/ance wire & !n out aga94 ,trace ! pa? ! electricity mu/ take f ! wire com+ into ! build+ d[n to ! fir/ swit* t x meets2 !n f "o end ( ! wire ?r\gh ! brass or copp] to :i* ! wire is screw$1 ?r\gh ! swit* & on out into ! end ( ! next piece ( wire4 ,turn ! fir/ swit* (f & see h[ a p>tition ( air is made betwe5 ! place :]e ! electricity comes 9 & ! place :]e x w\ld get out if x c\ld4 ,turn ! swit* on & notice h[ ?is gives ! electricity a complete pa? ?r\gh to ! next piece ( wire4 ,9 ?is way foll[ ! circuit on ?r\gh all ! swit*es to ! electric lamp4 ,if y exam9e ! socket into :i* ! lamp screws & exam9e ! lamp itself1 y w see t electricity :i* goes to ! out] "p ( ! socket passes into ! rim ( ! lamp2 f "h x goes into "o end ( ! filam5t4 ,x passes ?r\gh ! filam5t to ! o!r end1 :i* is connect$ to ! little brass disk at ! end ( ! lamp4 ,f ?is y c see t x goes into ! c5t] po9t ( ! socket1 & !n on into ! second wire t connects to ! socket4 ,trace ! curr5t on back ?r\gh ?is o!r wire until y see :]e ?is wire leads t[>d ! dynamo4 ,y %\ld und]/& t ! electric lamp1 ! swit*es1 ! fuses1 all ?+s along ! circuit1 are simply p>ts ( ! long loop f ! dynamo1 z %[n 9 ,figure #abd4 ,,connect+ ,,9 ,,p>allel4 ,! tr\ble ) ,figure #abd is t x is a little too simple4 ,f look+ at x y might ?9k t ! loop ent]$ only "o build+4 ,& x might seem t turn+ (f "o swit* w\ld %ut (f ! electricity all along ! l9e4 ,x w\ld1 too1 if ! circuit 7 arrang$ exactly z %[n above4 ,to avoid ?is1 & = o!r reasons1 ! ma9 loop f ! dynamo has bran*es s t ! electricity c g ?r\gh any or all ( !m at ! same "t & s t %utt+ (f "o bran* w n affect ! o!rs4 ,electricians call ?is connect+ 9 p>allel2 !re are _m p>allel circuits f "o p[] h\se4 ,illu/ration3 ,,fig4 #abd4 ,diagram ( ! complete circuit ?r\gh ! laboratory swit*es4 ,figure #abe illu/rates ! pr9ciple j expla9$4 ,z !re diagramm$1 ! electricity passes out f ! dynamo along ! l[] wire & goes d[n ! left-h& wire ( circuit ,a ?r\gh "o ( ! electric lamps t is turn$ on1 & !n x goes back ?r\gh ! "r-h& wire ( ! ,a circuit to ! upp] wire ( ! ma9 circuit & !n on back to ! dynamo4 ,b only a "p ( ! electricity goes ?r\gh ! ,a circuit2 "p goes on to ! ,b circuit1 & !re x passes p>tly ?r\gh ! electric iron4 ,!n x goes back ?r\gh ! o!r wire to ! dynamo4 ,no electricity c get ?r\gh ! electric lamp on ! ,b circuit1 because ! swit* to ! lamp is op54 ,! swit* on ! ,c circuit is op52 s no electricity c pass ?r\gh x4 ,! purpose ( ! diagram is to %[ t electricity f ! dynamo may g ?r\gh sev]al bran* circuits & !n get back to ! dynamo1 & t %utt+ (f ! electricity f "o bran* circuit does n %ut x (f f ! o!rs4 ,& ! purpose ( ?is section is to make x cle> t electricity c fl[ only ?r\gh a complete circuit2 x mu/ h an unbrok5 pa? f ! dynamo back to ! dynamo aga9 or f "o pole ( ! batt]y back to ! o!r pole4 ,if ! electricity does n h a complete circuit1 x w n fl[4 ,,application #eb4 ,a small boy disconnect$ ! doorbell batt]ies f ! wires t ran to !m1 & :5 he want$ to put ! wires back1 he c\ld n rememb] h[ !y _h be5 connect$4 ,he tri$ fa/5+ bo? wires to ! c>bon "p ( ! batt]y1 connect+ "o wire to ! c>bon & "o to ! z9c1 & connect+ bo? to ! z9c4 ,!n he decid$ t "o wire 0 all t _h to be connect$ anyway1 t ! second 0 simply to make x /rong]4 ,:i* ( ! ways he tri$1 if any1 w\ld h be5 "r8 ,illu/ration3 ,,fig4 #abe4 ,p>allel circuits4 ,illu/ration3 ,,fig4 #abf4 ,h[ %\ld he connect !m8 ,,application #ec4 ,doro?y 0 mov+4 ,:5 !y took out our telephone1 %e said to h] *um1 ,hel51 ! electrician j cut ! wires "r (f4 ,he mu/ h turn$ (f ! electricity fir/1 ,hel5 answ]$1 or else x w\ld all h run out ( ! cut ends ( ! wire & gone to wa/e4 ,:y1 x c\ldn't1 ,doro?y said4 ,electricity won't fl[ (f into ! air4 ,( c\rse x c if !re is no?+ to hold x 91 ,hel5 argu$4 ,:i* 0 "r8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cba4 ,x is v easy to get *ill$ :5 "o is p]spir+4 #cbb4 ,ice cream becomes liquid if y leave x 9 y\r di% too long4 #cbc4 ,y %\ld face =w>d :5 alight+ f a /reet c>4 #cbd4 ,!re are always at lea/ two electric wires go+ into a build+ t is wir$4 #cbe4 ,wool5 sweat]s keep y w>m4 #cbf4 ,/eel rails are n rivet$ to railroad ties b ! spikes are driv5 close to ea* rail s t ! heads hook ov] ! edge & hold ! rail d[n )\t absolutely prev5t+ its movem5t =w>d & backw>d4 ,:y %\ld rails be laid 9 ?is way8 #cbg4 ,! e>? keeps :irl+ ar\nd ! sun )\t fall+ into x1 al?\gh ! pull f ! sun is v great4 #cbh4 ,electricity is br\ght d[n f p[] h\ses 9 ! m\nta9s by means ( cables4 #cbi4 ,:ite clo!s are cool] ?an black :5 ! p]son we>+ !m is out 9 ! sun4 #ccj4 ,all ! /reet c>s along "o l9e are /opp$ :5 a trolley wire breaks4 ,,section #cf4 ,gr\nd$ circuits4 ,:y c a bird sit on a live wire )\t gett+ a %ock1 :ile a man w\ld get a %ock if he rea*$ up & took hold ( ! same wire8 ,we h j be5 lay+ emphasis on ! fact t = electricity to fl[ out ( a dynamo or batt]y1 x mu/ h a complete circuit back to ! batt]y or dynamo4 ,yet only "o wire is ne$$ 9 ord] to telegraph betwe5 two /ations4 ,likewise1 a s+le wire c\ld be made to c>ry into a build+ ! curr5t = electric lights4 ,?is is because ! gr\nd c c>ry electricity4 ,if y make all connections f a batt]y or dynamo j z = any complete circuit1 b use ! e>? = "o wire1 ! electricity w fl[ p]fectly well 7,fig4 #abg74 ,to connect an electric wire ) ! e>?1 ! wire mu/ g d[n deep into ! gr\nd & be well pack$ ) e>?2 b s9ce wat] pipes g d[n deep & ! e>? is already pack$ ar\nd !m1 ! mo/ conv5i5t way to gr\nd a circuit is to connect ! wire t %\ld g into ! gr\nd ) ! wat] pipe4 ,! next exp]im5t1 ! gr\nd+ ( a circuit1 %\ld be done by ! class ) ! help ( ! tea*]4 ,illu/ration3 ,,fig4 #abg4 ,! gr\nd c be us$ 9 place ( a wire to complete ! circuit4 ,,exp]im5t #fh4 ,caution3 ,keep ! swit*es turn$ (f ?r\gh\t ?is exp]im5t4#f ,footnote #f3 ,all ?r\gh ?is *apt] x is assum$ t ! electrical app>atus describ$ 9 ! app5dix is be+ us$4 ,9 ?is app>atus all ! swit*es are on "o wire1 ! o!r wire be+ alive ev5 :5 ! swit*es are turn$ (f4 7a7 ,put a piece ( fuse wire across ! fuse gap4 ,screw ! plug ) nails 9 x into ! lamp socket4 ,connect ! b>e end ( a piece ( insulat$ wire to ! wat] faucet & t\* ! o!r end to "o nail ( ! plug4 ,if no?+ happ5s1 t\* x to ! o!r nail in/ead4 ,! electricity has gone d[n into ! gr\nd ?r\gh ! wat] pipe1 in/ead ( into ! o!r wire4 ,! gr\nd c>ries ! electricity back to ! dynamo j z a wire w\ld4 7b7 ,put a new piece ( fuse wire across ! gap4 ,keep swit*es turn$ (f4 ,t\* ! brass disk at ! bottom ( an electric lamp to ! nail :i* work$1 & t\* ! wire f ! faucet to ! o!r brass "p ( ! lamp 7,fig4 #abi74 ,:at happ5s8 ,caution3 ,"u no circum/ances all[ ! swit* to be turn$ on :ile y are do+ any "p ( ?is exp]im5t4 ,"u no circum/ances t\* ! wire f ! faucet to ! b9d+ po/s ( ! fuse gap4 ,d only z direct$4 ,expla9 :at w\ld happ5 if y disobey$ ^! rules4 ,illu/ration3 ,,fig4 #abh4 ,gr\nd+ ! circuit4 ,! faucet & wat] pipe lead ! electricity to ! gr\nd4 ,,:y ,a ,,bird ,,is ,,n ,,electrocut$ ,,:5 ,,x ,,sits ,,on ,a ,,live ,,wire4 ,if a man accid5tally t\*es a live wire t c>ries a /rong curr5t ( electricity he is electrocut$2 yet birds p]* on su* a wire 9 p]fect safety4 ,if a man %\ld leap into ! air & grasp a live wire1 hang+ f x )\t t\*+ ! gr\nd1 he w\ld be no m hurt by x ?an a bird is4 ,a p]son :o is electrocut$ by t\*+ su* a wire mu/ at ! same "t be /&+ on ! gr\nd or on some?+ connect$ ) x4 ,! gr\nd completes ! electric circuit :i* passes ?r\gh ! body4 ,an electric circuit c always be complet$ ?r\gh ! gr\nd1 & :5 ?is is done1 x is call$ gr\nd+ a circuit4 ,illu/ration3 ,,fig4 #abi4 ,h[ ! lamp & wire are held to gr\nd ! circuit4 ,,application #ed4 ,expla9 :y only "o wire is ne$$ to telegraph betwe5 two /ations2 :y y %\ld n turn an electric light on or (f :ile /&+ 9 a tub ( wat]4 ,,application #ee4 ,9 a h\se 9 ! c\ntry1 ! electric wires pass$ ?r\gh a d\ble wall4 ,!y 7 sep>at$ f ea* o!r & well cov]$ ) insulation1 b !y 7 n )9 an iron pipe1 z is n[ requir$ 9 _m cities4 ,! curr5t 0 alt]nat+4 ,"o night :5 ! lights 7 out a rat 9 ! wall gnaw$ ?r\gh ! insulation ( ! wire & also gnaw$ cle> ?r\gh "o ( ! wires4 ,did he get a %ock8 ,! next morn+1 ! woman ( ! h\se want$ to use ! electric iron 9 ! kit*5 & x w\ld n "w4 ,! kit*5 _h 9 x a gas /ove1 a s9k ) runn+ wat]1 a table1 a c\ple ( *airs1 & ! usual kit*5 ut5sils4 ,!re 0 also a piece ( wire ab\t long en\gh to rea* across ! kit*54 ,! electrician c\ld n come out = sev]al h\rs1 & ! woman want$ v mu* to d h] iron+4 ,figure #acj is a diagram ( ! wires & ! kit*54 ,%[ :at ! woman might h done 9 ord] to use h] iron until ! electrician arriv$4 ,illu/ration3 ,,fig4 #acj4 ,h[ c ! electric iron be us$ aft] "o wire has be5 cut8 ,,application #ef4 ,a man want$ to *ange ! location ( ! wir+ 9 8 cem5t-floor$ g>age4 ,:ile he 0 work+1 w\ld x h be5 be/ = him to /& on ! b>e cem5t floor1 on a wire mat1 on an old automobile tire1 on a wet rug1 or on "s skid *a9s t 7 !re8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cca4 ,an ungreas$ :eel squeaks4 #ccb4 ,lightn+ rods ext5d into ! e>?4 #ccc4 ,a banjo play] moves 8 f+]s t[>d ! drum end ( ! banjo :5 he plays high notes4 #ccd4 ,:5 ! filam5t breaks1 an electric lamp w no long] gl[4 #cce4 ,an inv]t$ image is =m$ by ! l5s ( a cam]a4 #ccf4 ,a bl[n-out fuse may be replac$ tempor>ily ) a hairp9 or ) a copp] c5t4 #ccg4 ,sp>ks fly :5 a horse's %oe hits a /one4 #cch4 ,a room requires less artificial light if ! wall pap] is light ?an if x is d>k4 #cci4 ,phonographs usually h horns1 ei!r inside or outside4 #cdj4 ,an electric c> ne$s only "o wire to make x g4 ,,section #cg4 ,resi/ance4 ,:at makes an electric heat] hot8 ,:y does lightn+ kill p :5 x /rikes !m8 ,:at makes an electric light gl[8 ,we h talk$ ab\t mak+ electricity "w :5 x fl[s 9 a /eady /ream1 & ev]ybody kn[s t x makes lights gl[1 makes toa/]s & electric /oves hot1 & heats electric irons4 ,b did x ev] /rike y z rem>kable t ! same electricity t fl[s h>mlessly ?r\gh ! wires 9 y\r h\se )\t heat+ !m1 sudd5ly makes ! wire 9 y\r toa/] or ! filam5t 9 y\r inc&esc5t lamp gl[+ hot8 ,! insulation is n :at keeps ! wire cool1 z y c see by ! next exp]im5t4 ,,exp]im5t #fi4 ,betwe5 two ( ! laboratory swit*es y w f9d "o piece ( wire :i* has no insulation4 ,turn on ! electricity & make ! lamp gl[2 see t y are /&+ on dry wood & are n t\*+ any pipes or any?+ connect$ to ! gr\nd4 ,feel ! b>e piece ( wire ) y\r f+]s4 ,:y does ?is n give y a %ock8 ,:at w\ld happ5 if y t\*$ y\r o!r h& to ! gas pipe or wat] pipe8 ,d n try x6 ,b :at w\ld happ5 if y did8 ,! reason t ! filam5t ( ! electric lamp gets :ite hot :ile ! copp] wire /ays cool is ?is3 ,all sub/ances t conduct electricity resi/ ! fl[ some:at2 !re is some?+ l friction betwe5 ! wire & ! electricity pass+ ?r\gh x4 ,! small] ar\nd a wire is1 ! great] resi/ance x (f]s to ! pass+ ( an electric curr5t4 ,! filam5t ( an electric lamp is v f9e & !re=e (f]s consid]able resi/ance4 ,h[ev]1 if ! filam5t 7 made ( copp]1 ev5 z f9e z x is1 x w\ld take a mu* great] fl[ ( electricity to make x :ite hot1 & x w\ld be v exp5sive to use4 ,s filam5ts are n made ( copp] b ( sub/ances :i* d n conduct electricity ne>ly z well & :i* !re=e h mu* high] resi/ance4 ,c>bon 0 once us$1 b n[ a metal call$ tung/5 is us$ = mo/ inc&esc5t lamps4 ,bo? c>bon & tung/5 resi/ an electric curr5t s mu* t !y are easily heat$ :ite hot by x4 ,on ! o!r h&1 !y let s little curr5t ?r\gh t :at does pass fl[s ?r\gh ! l>g] copp] wires v easily & does n heat !m noticeably4 ,illu/ration3 ,,fig4 #aca4 ,feel+ "o live wire does n give h] a %ock1 b :at w\ld happ5 if %e t\*$ ! gas pipe ) h] o!r h&8 ,,exp]im5t #gj4 ,turn on ! swit* t lets ! electricity fl[ ?r\gh ! long resi/ance wire t passes ar\nd ! porcela9 po/s4 ,wat* ! wire4 ,! resi/ance wire y are us+ is an alloy1 a mixture ( metals t w resi/ electricity mu* m ?an ord9>y metals w4 ,?is is ! same k9d ( wire t is us$ 9 electric irons & toa/]s & heat]s4 ,x has s great a resi/ance to ! electricity t x is heat$ r$ hot1 or almo/ :ite hot1 by ! electricity pass+ ?r\gh x4 ,,application #eg4 ,a p[] company want$ to s5d l>ge quantities ( electricity d[n f a m\nta94 ,%\ld ! company h obta9$ resi/ance wire or copp] wire to c>ry x8 ,%\ld ! wire h be5 l>ge or f9e8 ,,application #eh4 ,a firm 0 mak+ electric toa/]s4 ,9 ! exp]im5tal laboratory !y tri$ v>i\s weights ( resi/ance wire = ! toa/]s4 ,!y tri$ a v f9e wire1 ,no4 #cj2 a m$ium weight wire1 ,no4 #bd2 & a heavy wire1 ,no4 #ah4 ,"o ( ^! wires did n get hot en\gh1 & x took s mu* electricity t x w\ld h be5 too exp5sive to run2 ano!r got s hot t x soon burn$ out4 ,"o work$ satisfactorily4 ,:i* ( ! ?ree sizes burn$ out8 ,:i* 0 satisfactory8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cda4 ,if y atta* "o end ( a wire to a wat] faucet & connect ! o!r end to an electric lamp 9 place ( "o ( ! regul> light+ wires1 ! lamp w light4 #cdb4 ,! ne$le ( a sew+ ma*9e goes up & d[n _m times to ea* /roke ( ! treadle4 #cdc4 ,trolley wires are b>e4 #cdd4 ,if y _h rubb]s on y\r feet1 y c\ld take hold ( "o live wire ) p]fect safety1 provid$ y t\*$ no?+ else4 #cde4 ,if y 7 on ! moon1 y w\ld look up at ! e>?4 #cdf4 ,toy balloons bur/ :5 !y g high up :]e ! air is ?94 #cdg4 ,y h to put on ! brakes to /op a c> quickly4 #cdh4 ,telephone wires are /rung on glass support]s4 #cdi4 ,if y p\r boil+ wat] into a dr9k+ glass1 frequ5tly ! glass w crack4 #cej4 ,an asbe/os mat t5ds to keep food f burn+4 ,illu/ration3 ,,fig4 #acb4 ,p5cils ready = mak+ an arc light4 ,,section #ch4 ,! electric arc4 ,h[ c electricity set a h\se on fire8 ,,?is ,,is ,,"o ,,( ,,! ,,mo/ ,,important ,,sections ,,9 ,,! ,,book4 ,d y "k t y c make an arc light ) two ord9>y p5cils8 ,! next exp]im5t1 :i* %\ld be done by ! class ) ! help ( ! tea*]1 %[s h[ to d x4 ,,exp]im5t #ga4 ,%>p5 two p5cils4 ,ab\t halfway betwe5 ! po9t & ! o!r end ( ea* p5cil cut a not* all ! way ar\nd & d[n to ! lead1 or burn a not* d[n by means ( ! gl[+ resi/ance wire4 ,:at y call ! lead ( ! p5cil is really graphite1 a =m ( c>bon4 ,! leads ( y\r two p5cils are almo/ exactly l ! c>bons us$ 9 arc lights1 except1 ( c\rse1 t !y are mu* small]4 ,turn (f ! electricity bo? at ! snap swit* & at ! knife swit*4 ,fa/5 ! b>e end ( a #b-;foot piece ( f9e insulat$ wire 7ab\t ,no4 #bd7 ar\nd ! c5t] ( ! lead 9 ea* p5cil s t y get a good contact1 z %[n 9 ,figure #acb4 ,fa/5 ! o!r b>e end ( ea* wire to ei!r side ( ! op5 knife swit* s t :5 ?is swit* is op5 ! electricity w h to pass d[n "o wire to ! lead ( "o p5cil1 f t to ! lead ( ! o!r p5cil1 & f t back ?r\gh ! second wire to ! o!r side ( ! knife swit* & on ar\nd ! circuit1 z %[n 9 ,figure #acc4 ,keep ! two p5cils ap>t & (f ! desk1 :ile "s "o turns on ! snap swit* & ! flu% swit* t lets ! electricity ?r\gh ! resi/ance wire4 ,n[ br+ ! p5cil po9ts toge!r = an in/ant1 imm$iately draw+ !m ap>t ab\t half an in*4 ,y %\ld get a brilliant :ite arc light4 ,caution3 ,d n look at ?is brilliant arc = m ?an a fraction ( a second unless y look ?r\gh a piece ( smok$ or color$ glass4 ,bl[ out ! flame :5 ! wood cat*es fire4 ,aft] y h done ?is two or ?ree times1 ! inside ( ! wood bel[ ! not*es w be burn$ out s completely t y c pull x (f ) y\r f+]s1 leav+ ! lead b>e all ! way up to ! wires4 ,let ! class /& well back & wat* ! tea*] d ! next "p ( ! exp]im5t4 ,connect two heavy insulat$ copp] wires1 ab\t ,no4 #ab1 to ! sides ( ! knife swit* j z y connect$ ! f9e wires4 ,b ?is "t br+ ! ends ( ! copp] wires !mselves toge!r = an in/ant1 !n draw !m ap>t4 ,hold ! ends ( ! wires ov] ! z9c ( ! table :ile y d ?is1 z melt$ copp] w drop f !m4 ,illu/ration3 ,,fig4 #acc4 ,! p5cil po9ts are t\*$ toge!r & imm$iately drawn ap>t4 ,illu/ration3 ,,fig4 #acd4 ,a brilliant arc light is ! result4 ,,:at ,,happ5s ,,:5 ,,an ,,arc ,,is ,,=m$4 ,:at happ5s :5 y =m an electric arc is ?is3 ,z y draw ! two ends ( ! p5cils ap>t1 only a speck ( ! lead 9 ea* t\*es ! o!r4 ,! electricity pass+ = an in/ant ?r\gh ! la/ speck at ! end ( ! p5cil makes x s hot t x turns to vapor4 ,! vapor w let electricity g ?r\gh x1 & makes a bridge f "o p5cil po9t to ! o!r4 ,b ! vapor gets v hot1 because x has a r high resi/ance4 ,?is heat vaporizes m c>bon & makes m vapor = ! electricity to pass ?r\gh1 & s on4 ,! electricity pass+ ?r\gh ! c>bon vapor makes x :ite hot1 & t is :at causes ! brilliant gl[4 ,regul> arc lights are made exactly l ?is exp]im5tal "o1 except t ! c>bons us$ are mu* bigg] & are made to /& ! heat bett] ?an ! small c>bons 9 y\r p5cil4 ,c>bon is "o ( ^? sub/ances t turn directly f a solid to a gas )\t fir/ melt+4 ,t is "o reason :y x is us$ = arc lights4 ,b copp] melts :5 x becomes v hot1 z y saw :5 y made an arc light ) ! copp] wires4 ,s copp] _c be us$ = practical arc lights4 ,,fires ,,caus$ ,,by ,,arcs4 ,!re is "o extremely important po9t ab\t ?is exp]im5t ) arcs3 mo/ fires t result f defective wir+ are caus$ by ! =m+ ( arcs4 ,y see1 if two wires t\* ea* o!r :ile ! curr5t is pass+ & !n move ap>t a little1 an arc is =m$4 ,& y h se5 h[ int5sely hot su* an arc is4 ,two wires rubb+ aga9/ ea* o!r1 or a wire n screw$ tightly to its connection1 c arc4 ,a wire brok51 b ) its ends close en\gh toge!r to t\* & !n g ap>t1 c cause an arc4 ,& an arc is v dang]\s 9 a h\se if !re is any?+ burnable ne> x4 ,wires %\ld nev] be j twi/$ toge!r & !n b\nd ) tape to =m a jo9t4 ,twi/$ wires sometimes break & sometimes come loose2 !n an arc =ms1 & ! h\se cat*es fire4 ,good wir+ always means sold]+ e jo9t & screw+ ! ends ( ! wires tightly into ! swit*es or sockets to :i* !y lead4 ,illu/ration3 ,,fig4 #ace4 ,an arc lamp4 ,! c>bons are mu* l>g] ?an ! c>bons 9 ! p5cils1 & ! arc gives an int5se light4 ,,keep+ ,,arcs ,,f ,,=m+4 ,well-wir$ h\ses h ! wires br\ght 9 ?r\gh iron pipes1 call$ conduits1 & ! conduits are always gr\nd$2 s if an arc %\ld =m any:]e along ! l9e1 ! h\se w\ld be protect$ by an iron conduit & if "o ( ! loose ends ( wire came 9 contact ) ! conduit1 ! curr5t w\ld ru% to ! gr\nd ?r\gh x1 bl[+ out a fuse4 ,! next section tells ab\t ! purpose ( fuses4 ,! directions t usually come ) electric irons1 toa/]s1 & /oves say t ! connection %\ld be brok5 by pull+ out ! plug r ?an by turn+ (f ! swit*4 ,?is is because ! swit* 9 ! electric-light socket sometimes loses its spr+ & in/ead ( snapp+ all ! way ar\nd & quickly leav+ a big gap1 x moves only a little way ar\nd & an arc is =m$ 9 ! socket2 if y he> a sizzl+ s\nd 9 a socket1 y may be pretty sure t an arc has be5 =m$4 ,b :5 y pull ! plug entirely out ( ! iron or /ove1 ! gap is too big = an arc to =m & y are p]fectly safe4 ,fire commissions usually condemn ext5sion lights1 because if ! insulation we>s out on a lamp cord s t ! two wires c come 9 contact1 a dang]\s arc may easily =m4 ,& ! insulation might sudd5ly be scrap$ (f by some?+ heavy mov+ across ! cord4 ,?is c happ5 :e!r ! light at ! end ( ! cord is turn$ on or (f4 ,s x is be/ if y h an ext5sion light always to turn x (f at ! socket f :i* ! cord leads1 n at ! lamp itself4 ,_m p d n d ?is1 & g = ye>s )\t hav+ a fire4 ,b s might y live = ye>s ) a /ick ( dynamite 9 y\r bureau draw] & nev] h an explosion4 ,/ill1 x is n wise to keep dynamite 9 y\r bureau4 ,arc lights !mselves1 ( c\rse1 are no m dang]\s ?an is a fire 9 a kit*5 /ove4 ,= an arc light is plac$ 9 su* a way t no?+ c well come ne> x to cat* fire4 ,! dang] f ! electric arc is l ! dang] f gasol9e spill$ & mat*es dropp$ :]e y are n expect+ !m1 s t y are n protect$ aga9/ !m4 ,=tunately ord9>y batt]ies h n en\gh voltage to cause dang]\s arcs4 ,s y d n h to be z c>eful 9 wir+ = electric bells & telegraph in/rum5ts4 ,x requires ! high voltage ( a city p[] l9e to make a dang]\s electric arc4 ,s _m fires are caus$ by electric arcs =m+ 9 build+s1 t y _h bett] g back to ! beg9n+ ( ?is section & read x all ?r\gh aga9 c>efully4 ,x may save y\r home & ev5 y\r life4 ,aft] y h r]ead ?is section1 te/ y\r und]/&+ ( x by answ]+ ! foll[+ que/ions3 #a4 ,h[ c y make an electric arc8 #b4 ,:y %\ld wires n be twi/$ toge!r to make electric connections8 #c4 ,:y %\ld wires be br\ght into h\ses & ?r\gh walls 9 iron conduits8 #d4 ,:y %\ld y pull out ! plug ( an electric iron1 p]colator1 toa/]1 heat]1 or /ove8 #e4 ,:y d fire commissions condemn ext5sion lights8 #f4 ,if y use an ext5sion light1 :]e %\ld x be turn$ (f8 #g4 ,if y he> a sizzl+ & sputt]+ 9 y\r electric-light socket1 :at does x mean8 ,:at %\ld y d8 #h4 ,is !re any dang] 9 defective sockets ) swit*es t d n snap (f completely8 ,:at is ! dang]8 #i4 ,9 ,application #ee1 page #bbh1 if ! rat _h gnaw$ ! wire 9 two :ile ! electric iron 0 be+ us$1 w\ld any?+ h happ5$ to ! rat8 ,w\ld !re h be5 any dang] to ! h\se8 #aj4 ,:]e a wire is screw$ into an electric-light socket1 :at h>m1 if any1 might result f n screw+ x 9 tightly8 #aa4 ,h[ c a wire be safely splic$8 #ab4 ,:y is an electric arc 9 a circuit dang]\s8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cea4 ,:ite objects look blue :5 se5 ?r\gh a blue glass4 #ceb4 ,:5 y pull ! plug out ( an electric iron1 ! iron cools4 #cec4 ,p :o d n he> well sometimes use speak+ trumpets4 #ced4 ,! s\nd+ bo>d ( a piano is r\ghly triangul>2 ! longe/ /r+s are ! extreme left1 & ^? to ! "r get %ort] & %ort]4 #cee4 ,birds c sit on live wires )\t gett+ a %ock4 #cef4 ,deaf p c sometimes id5tify musical selections by hold+ _! h&s on ! piano4 #ceg4 ,an electric toa/] gets hot :5 a curr5t passes ?r\gh x4 #ceh4 ,! cord ( an electric iron sometimes cat*es fire :ile ! iron is 9 use1 especially if ! cord is old4 #cei4 ,if a live wire t\*es ! e>? or any?+ connect$ ) x1 ! curr5t ru%es into ! e>?4 #cfj4 ,:5 y /ub y\r toe1 y h to run =w>d to keep f fall+4 ,,section #ci4 ,%ort circuits & fuses4 ,:y does a fuse bl[ out8 ,sometimes dur+ ! ev5+ :5 ! lights are all on 9 y\r home1 "s "o t9k]s ) a "p ( ! electric circuit or turns on an electric heat] or iron1 & sudd5ly all ! lights 9 t "p ( ! h\se g out4 ,a fuse has bl[n out4 ,if y h no extra fuses on h&1 x may be necess>y to wait till ! next day to replace ! "o t is bl[n out4 ,x is always a good idea to keep a c\ple ( extra fuses2 !y co/ only #aj c5ts ea*4 ,& if y d n happ5 to "k h[ fuses "w or h[ to replace !m :5 !y bl[ out1 x w co/ a doll> or s to get an electrician to put 9 a new fuse4 ,! next ?ree exp]im5ts w help y to und]/& fuses4 ,illu/ration3 ,,fig4 #acf4 ,a1 ! fuse gap & ,b1 ! nail plug4 ,,exp]im5t #gb4 ,on ! l[] wire lead+ to ! electric lamp 9 ! laboratory y w f9d a gap1 a place :]e ! wire ends 9 a piece ( a knife swit*1 & !n beg9s aga9 ab\t an in* away 9 ano!r piece ( ! swit*1 z %[n 9 ,figure #acf4 ,!re mu/ be "s k9d ( wire or metal t w conduct electricity across ?is gap4 ,b ! gap is !re to prev5t z mu* electricity f fl[+ ?r\gh z might fl[ ?r\gh copp] wire4 ,s nev] put copp] wire across ?is gap4 ,if y d1 y w h to pay = ! o!r fuses :i* may bl[ out4 ,always keep a piece ( fuse wire /ret*$ across ! gap4 ,fuse wire is a s(t leadlike wire1 :i* melts z soon z too mu* electricity passes ?r\gh x4 ,unscrew ! lamp1 & into ! socket :]e x 01 screw ! plug ) ! two nails /ick+ out ( x4 ,turn ! electricity on4 ,does any?+ happ58 ,turn ! electricity (f4 ,n[ t\* ! heads ( ! two nails toge!r1 or connect !m ) a piece ( any metal1 & turn on ! electricity4 ,:at happ5s8 ,exam9e ! pieces ( ! fuse wire t are left4 ,x 0 s easy = ! electricity to pass ?r\gh ! nails & wire1 t x gu%$ ?r\gh at a trem5d\s rate4 ,?is melt$ ! fuse wire1 or blew out ! fuse4 ,if ! fuse across ! gap by ! socket _h n be5 ! m easily burn$ out1 "o or p]haps bo? ( ! m exp5sive fuses up above1 :]e ! wire comes 91 w\ld h bl[n out4 ,^! co/ ab\t #aj c5ts ea* to replace1 :ile ! fuse wire y burn$ out co/s only a fraction ( a c5t4 ,if !re 7 no fuses 9 ! laboratory wir+s & y _h %ort circuit$ ! electricity 7giv5 x an easy en\gh pa?71 x w\ld h bl[n out ! mu* m exp5sive fuses :]e ! electricity ent]s ! build+4 ,if !re 7 no big fuses :]e ! electricity ent]s ! build+1 ! ru% ( electricity w\ld make all ! copp] wires ?r\gh :i* x fl[$ inside ! build+ s hot t !y w\ld melt & set fire to ! build+4 ,z long z y keep a piece ( fuse wire across ! gap1 !re is no dang] f %ort circuits4 ,,:y ,,fuse ,,wire ,,melts4 ,= two reasons1 ! fuse wire melts :5 ord9>y wire w\ld n4 ,fir/1 x has en\gh resi/ance to electricity s t if _m amp]es 7mu* curr5t7 fl[ ?r\gh1 x gets heat$4 ,x has n ne>ly z mu* resi/ance1 h[ev]1 z ! filam5t 9 an electric lamp or ev5 z has ! long resi/ance wire4 ,x does n become :ite hot z !y d4 ,second1 x has a l[ melt+ po9t4 ,x melts imm$iately if y hold a mat* to x2 try ?is & see4 ,consequ5tly1 long be=e ! fuse wire becomes r$ hot1 x melts 9 two4 ,x has en\gh resi/ance to make x hot z soon z too _m amp]es fl[ ?r\gh2 & x has su* a l[ melt+ po9t t z soon z x gets hot x melts 9 two1 or bl[s out4 ,?is breaks ! circuit1 ( c\rse1 s t no m electricity c fl[4 ,9 ?is way ! fuse protects h\ses f cat*+ fire ?r\gh %ort circuits4 ,illu/ration3 ,,fig4 #acg4 ,:at w happ5 :5 ! p9 is ?ru/ ?r\gh ! cords & ! electricity turn$ on8 ,un=tunately1 h[ev]1 ! fuse is almo/ no protection aga9/ an electric arc4 ,! copp] vapor ?r\gh :i* ! electricity passes 9 an arc has en\gh resi/ance to keep ! amp]age 7curr5t7 l[2 s ! arc may n bl[ out ! fuse at all4 ,b if x 7 n = fuses1 !re w\ld be ab\t z mu* dang] ( h\ses be+ set on fire by %ort circuits z by arcs4 ,p]haps !re w\ld be m dang]1 because %ort circuits are ! m common4 ,,exp]im5t #gc4 ,put a new piece ( fuse wire across ! fuse gap4 ,leave ! nail plug screw$ 9 ! socket4 ,use a piece ( flexible lamp cord--! k9d t is made ( two /r&s ( wire twi/$ toge!r 7see ,fig4 #acg74 ,fa/5 "o b>$ end ( ea* wire ar\nd ea* nail ( ! nail plug4 ,see t ! o!r ends ( ! lamp cord are n t\*+ ea* o!r4 ,turn on ! electricity4 ,does any?+ happ58 ,turn (f ! electricity4 ,n[ put a p9 /raight ?r\gh ! middle ( ! two wires4 ,turn on ! electricity aga94 ,:at happ5s8 ,!re is n mu* resi/ance 9 ! p91 & s x all[s ! electricity to ru% ?r\gh x4 ,p sometimes cause fuses to bl[ out by p9n+ pictures to electric lamp wires or by p9n+ ! wires up out ( ! way4 ,a ,,%ort ,,circuit ,,an ,,easy ,,circuit4 ,y always get a %ort circuit :5 y give electricity an easy way to get f "o wire to ! o!r4 ,b y get no curr5t unless y give x "s way to pass f "o wire to ! o!r1 ?us complet+ ! circuit4 ,!re=e y %\ld always complete ! circuit ?r\gh some?+ :i* resi/s ! fl[ ( electricity1 l an electric lamp1 a heat]1 or an iron4 ,rememb] ?is & y w h ! key to an und]/&+ ( ! practical use ( electricity4 ,! t]m %ort circuit is a little confus+1 9 t electricity may h to g a long] way to be %ort circuit$ ?an to pass ?r\gh "s resi/ance1 su* z a lamp4 ,really a %ort circuit %\ld be call$ an easy circuit or some?+ l t1 to indicate t x is ! pa? ( lea/ resi/ance4 ,:]ev] ! electricity has a *ance to complete its circuit )\t go+ ?r\gh any consid]able resi/ance1 no matt] h[ f> x goes1 we h a %ort circuit4 ,& s9ce ev]y?+ resi/s electricity a little1 a l>ge en\gh fl[ ( electricity w\ld ev5 heat a copp] wire r$ hot2 t is :y a %ort circuit w\ld be dang]\s if y _h no fuses4 ,,application #ei4 ,to te/ y\r k ( %ort circuits & fuses1 trace ! curr5t c>efully f ! upp] wire z x ent]s ! laboratory1 ?r\gh ! plug fuse4 ,%[ :]e x comes f to ent] ! plug fuse1 exactly h[ x goes ?r\gh ! fuse1 :]e x comes out1 & :]e x goes f !re4 ,trace x on ?r\gh ! c>tridge fuse 9 ! same way1 ?r\gh all ! swit*es into ! lamp socket1 ?r\gh ! lamp1 out ( ! lamp socket to ! fuse gap1 across ?is to ! o!r wire1 & on out ( ! room4 ,x goes on f !re ?r\gh m fuses & back to ! dynamo f :i* ! o!r wire comes4 ,te/ y\rself fur!r ) ! foll[+ que/ions3 #a4 ,:]e 9 ?is circuit is ! resi/ance suppos$ to be8 #b4 ,:at happ5s :5 y put a good conductor 9 place ( ?is resi/ance if ! electricity c get f "o wire to ! o!r )\t pass+ ?r\gh ?is resi/ance8 #c4 ,:y d we use fuses8 #d4 ,:at is a %ort circuit8 #e4 ,:at makes an electric toa/] get hot8 #f4 ,:y %\ld y n /ick p9s ?r\gh electric cords8 ,,exp]im5t #gd4 ,take ! fuse wire out ( ! fuse gap & put a s+le /r& ( z9c %av+ 9 its place4 ,in/ead ( ! nail plug1 screw ! lamp into ! socket4 ,d n turn on ! swit* t lets ! electricity fl[ ?r\gh ! resi/ance wire1 b turn on ! electricity s t ! lamp w gl[4 ,does ! z9c %av+ "w satisfactorily z a fuse wire8 ,n[ turn ! electricity on ?r\gh ! resi/ance wire4 ,:at happ5s8 ,:5 are ! great] numb] ( amp]es ( electricity fl[+ ?r\gh ! z9c %av+8 7,,note4 ,amp]es means ! am\nt ( curr5t fl[+47 ,c ! z9c %av+ /& z _m amp]es z ! fuse wire y ord9>ily use8 ,:i* lets m electricity pass ?r\gh x1 ! lamp or ! resi/ance wire8 ,:y d electric irons & toa/]s (t5 bl[ out fuses8 ,if ?is happ5s at y\r home1 exam9e ! fuse & see h[ _m amp]es 7h[ mu* curr5t7 x w all[ to fl[ ?r\gh x4 ,x w say #f;,a if x all[s #f amp]es to pass ?r\gh x2 #be;,a if x all[s #be amp]es to pass ?r\gh x1 etc4 ,! fuse wire across ! fuse gap all[s ab\t #h amp]es to pass ?r\gh be=e x melts4 ,! z9c %av+ all[s only ab\t #b4 ,read ! m>ks on ! c>tridge & plug fuses4 ,h[ _m amp]es w !y /&8 ,,application #fj4 ,a family _h j secur$ an electric heat]4 ,! fir/ night x 0 us$1 ! fuse blew out4 ,! boy said3 ,let's put a piece ( copp] wire across ! fuse socket2 !n !re c't be any m tr\ble4 ,! fa!r said t !y _h bett] get a new fuse to replace ! old "o4 ,! old fuse 0 m>k$ #aj;,a4 ,0 ! boy or 0 ! fa!r "r8 ,if ! fa!r 0 "r1 %\ld !y h got a fuse m>k$ #f;,a1 "o m>k$ #aj;,a1 or "o m>k$ #ae;,a8 ,,application #fa4 ,! family 7 putt+ up an ext5sion light4 ,!y want$ ! cord held firmly up out ( ! way4 ,"o sugge/$ t !y drive a nail ?r\gh bo? p>ts ( ! cord & into ! wall4 ,ano!r ?\ght x w\ld be bett] to put a loop ( /r+ ar\nd ! cord & fa/5 ! loop to ! wall4 ,a ?ird sugge/$ ! use ( a d\ble-po9t$ c>pet tack t w\ld g across ! wires1 b n ?r\gh !m1 & if driv5 tightly into ! wall w\ld hold ! wire m firmly ?an w\ld ! loop4 ,:i* way 0 be/8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cfa4 ,if ! insulation we>s (f bo? wires ( a lamp cord1 ! fuse w bl[ out4 #cfb4 ,/reet c>s are heat$ by electricity4 #cfc4 ,! h&les ( pancake turn]s are (t5 made ( wood4 #cfd4 ,glue soaks into ! pores ( pieces ( wood & gradually h>d5s4 #cfe4 ,! glue !n holds ! pieces tightly toge!r4 #cff4 ,y ne$ a fuse ( high] amp]age1 z a #aj-;amp]e fuse1 in/ead ( a #f-;amp]e "o1 :]e y use electricity = an iron1 & "o ( /ill high] amp]age = an electric /ove4 #cfg4 ,y %\ld be c>eful ab\t turn+ on electric lights or do+ any?+ ) electric wires :5 y are on a cem5t1 iron1 or e>!n floor1 or if y are /&+ 9 wat]4 #cfh4 ,! keys & buttons ) :i* y turn on electric lights are usually made ( a rubb] composition4 #cfi4 ,defective wir+1 because ( :i* b>e wires may t\*1 has caus$ _m fires4 #cgj4 ,a p]son we>+ glasses c sometimes see 9 !m ! image ( a p]son beh9d him4 ,,section #dj4 ,electromagnets4 ,h[ is a telegram s5t8 ,:at c>ries y\r voice :5 y telephone8 ,s f> we h talk$ ab\t electricity only mak+ heat & light by be+ =c$ ?r\gh some?+ t resi/s x4 ,b ev]ybody kn[s t electricity c be made to d ano!r k9d ( "w4 ,x c be made to move ?+s1--to run /reet c>s1 to click telegraph in/rum5ts1 to vibrate ! ?9 metal disk 9 a telephone receiv]1 & s on4 ,! foll[+ exp]im5ts w %[ y h[ electricity moves ?+s3 ,illu/ration3 ,,fig4 #ach4 ,! magnetiz$ bolt picks up ! iron fil+s4 ,,exp]im5t #ge4 ,b>e an in* ( ea* end ( a piece ( insulat$ wire ab\t #aj feet long4 ,fa/5 "o end to ! z9c ( y\r batt]y or to "o wire f ! /orage batt]y2 wrap ! wire ar\nd & ar\nd an iron ma*9e bolt1 leav+ ! bolt a foot or s f ! batt]y1 until y h only ab\t a foot ( wire left4 ,hold y\r bolt ov] "s iron fil+s4 ,is x a magnet8 ,n[ t\* ! free end ( y\r wire to ! c>bon ( y\r batt]y or to ! o!r wire f ! /orage batt]y1 & hold ! bolt ov] ! iron fil+s4 ,is x a magnet n[8 ,y h complet$ ! circuit by t\*+ ! free end ( ! wire to ! free pole ( y\r batt]y2 s ! electricity fl[s ?r\gh ! wire1 ar\nd ! bolt1 & back to ! batt]y4 ,disconnect "o end ( ! wire f ! batt]y4 ,y h n[ brok5 ! circuit1 & ! electricity c no long] fl[ ar\nd ! bolt to magnetize x4 ,see if ! bolt w pick up ! iron fil+s any m2 x may keep a little ( its magnetism ev5 :5 no electricity is fl[+1 b ! magnetism w be noticeably less4 ,:5 y disconnect ! wire s t ! electricity c no long] fl[ ?r\gh a complete circuit f its s\rce back to its s\rce aga91 y are said to break ! circuit4 ,illu/ration3 ,,fig4 #aci4 ,s5d+ a message ) a cig>-box telegraph4 ,,exp]im5t #gf4 ,exam9e ! cig>-box telegraph 7see ,app5dix ,b7 & notice t x is made on ! same pr9ciple z 0 ! magnetiz$ bolt 9 ,exp]im5t #ge4 ,complete ! circuit ?r\gh ! electromagnet 7! bolt w\nd ) wire7 by connect+ ! two ends ( ! wire t is wrapp$ ar\nd ! bolt1 ) wires f ! two poles ( ! batt]y4 ,by mak+ & break+ ! circuit 7connect+ & disconnect+ "o ( ! wires7 y %\ld be able to make ! l[] bolt jump up & d[n & give ! *>act]i/ic click ( ! telegraph in/rum5t4 ,9 ?is exp]im5t x does n matt] h[ long ! wires are if ! batt]ies are /rong en\gh4 ,( c\rse x makes no diff]5ce :]e y break ! circuit4 ,s y c\ld h ! batt]ies 9 ! laboratory & ! cig> box a hundr$ miles away1 ) ! wire go+ f ! batt]ies to ! bolt & back aga94 ,!n if y made & broke ! circuit at ! laboratory1 ! in/rum5t w\ld click a hundr$ miles away4 ,if y want to1 y may take ! cig>-box telegraph out into ! y>d1 leav+ ! batt]ies 9 ! laboratory1 :ile y try to telegraph ?is %ort di/ance4 ,exam9e a regul> telegraph in/rum5t4 ,trace ! wire f "o b9d+ po/1 ar\nd ! coil & ?r\gh ! key1 back to ! o!r b9d+ po/1 & notice h[ pu%+ d[n ! key completes ! circuit & h[ rais+ x up breaks ! circuit4 ,illu/ration3 ,,fig4 #adj4 ,connect+ up a real telegraph in/rum5t4 ,,exp]im5t #gg4 ,connect two regul> telegraph in/rum5ts1 leav+ "o at ea* end ( ! long laboratory table4 ,make ! connections z foll[s3 ,take a wire long en\gh to g f "o in/rum5t to ! o!r4 ,fa/5 ! b>e ends ( ?is wire into ! "r-h& b9d+ po/ ( ! in/rum5t at y\r left1 & into ! left-h& b9d+ po/ ( ! in/rum5t at y\r "r2 t is1 connect ! b9d+ po/s t are ne>e/ toge!r1 z 9 ,figure #ada4 ,n[ connect "o wire f ! laboratory batt]y to ! free po/ ( ! "r-h& in/rum5t4 ,connect ! o!r wire f ! laboratory batt]y to ! gr\nd ?r\gh a faucet1 radiator1 or gas pipe1 mak+ ! connection firm & be+ sure t !re is a good1 cle> contact betwe5 ! b>e end ( ! wire & ! metal to :i* ! wire is atta*$4 ,make ano!r gr\nd connection ne> ! left-h& in/rum5t2 t is1 take a wire long en\gh to rea* f "s pipe or radiator to ! left-h& telegraph in/rum5t1 b9d "o b>e end ( ?is wire firmly to a clean "p ( ! pipe & br+ ! o!r end t[>d ! in/rum5t4 ,be=e atta*+ ?is o!r end to ! free b9d+ po/ ( ! left-h& in/rum5t1 be sure to op5 ! swit* beside ! telegraph key by pu%+ x to y\r "r4 ,close ! swit* on ! o!r in/rum5t4 ,n[ atta* ! free gr\nd wire to ! free b9d+ po/ ( y\r telegraph in/rum5t1 & press ! key4 ,does ! o!r in/rum5t click8 ,if n1 disconnect ! gr\nd wire & exam9e all connections4 ,also press ! s\nd] ( ea* in/rum5t d[n & see if x spr+s back readily4 ,x may be t "s screw is too tight1 or too loose1 or t a spr+ has come (f2 t9k] a:ile & see if y _c make ! in/rum5t "w4 ,if y are unable to d s1 ask = help4 ,figure #ada is a diagram ( all ! connections4 ,:5 y want to telegraph1 op5 ! swit* ( ! in/rum5t y want to s5d f & close ! swit* ( ! in/rum5t :i* is to receive ! message4 ,hold+ ! key d[n a little :ile1 !n lett+ x up1 makes a da%1 :ile lett+ x spr+ up in/antly1 makes a dot4 ,practice mak+ dots & da%es4 ,telegraph ! ^w cat1 us+ ! alphabet %[n on ! next page4 ,telegraph y\r own "n2 y\r address4 ,illu/ration3 ,,fig4 #ada4 ,diagram %[+ h[ to connect up two telegraph in/rum5ts4 ,! circles on ! tables repres5t ! b9d+ po/s ( ! in/rum5ts4 ,illu/ration3 ,,fig4 #adb4 ,telegraph+ across ! room4 ,"h is ! ,morse telegraph code 9 dots & da%es3 ,,lett]s ,a ,b ,c ,d ,e ,f ,g - - - - -- ,h ,i ,j ,k ,l ,m ,n -- -- -- - - - ,o ,p ,q ,r ,s ,t ,u - - - ,v ,w ,x ,y ,z - -- - ,,num]als #a #b #c #d #e -- - - - --- #f #g #h #i #j -- - -- ---- ,by us+ ! ,morse code1 telegraph & cable messages are s5t all ov] ! _w 9 a few seconds4 ,! ability to s5d messages 9 ?is way arose f ! simple discov]y t :5 an electric curr5t passes ar\nd a piece ( iron1 x turns ! iron into a magnet4 ,,h[ ,a ,,telephone ,,works4 ,a telephone is mu* l a delicate & complicat$ telegraph 9 :i* ! vibrations />t$ by y\r voice press ! key1 & 9 :i* ! s\nd] c vibrate swiftly 9 response to ! electric curr5ts pass+ ?r\gh ! wire4 ,! key 9 ! telephone is a ?9 metal disk t vibrates easily1 back ( ! rubb] m\?piece4 ,ea* "t an air vibration f y\r voice presses aga9/ x1 x increases ! curr5t fl[+ 9 ! circuit4 ,& ea* "t ! curr5t 9 ! circuit is increas$1 ! disk 9 ! receiv] is pull$ d[n1 j z ! s\nd] ( a telegraph is pull$ d[n4 ,s e vibration ( ! disk back ( ! m\?piece causes a vibration ( ! disk 9 ! receiv] ( ! o!r telephone2 ?is makes ! air ov] x vibrate j z y\r voice made ! m\?piece vibrate1 & y get ! same s\nd4 ,to make a diff]5ce betwe5 slight vibrations & l>g] ones 9 telephones1 !re are "s c>bon granules betwe5 ! m\?piece disk & a disk beh9d x2 & !re are v>i\s o!r complications1 su* z ! bell-r++ app>atus & ! connections 9 ! c5tral (fice4 ,b ! pr9ciple ( ! telephone is almo/ exactly ! same z ! pr9ciple ( ! telegraph4 ,bo? dep5d entirely on ! fact t an electric curr5t pass+ ar\nd a piece ( iron magnetizes ! iron4 ,,exp]im5t #gh4 ,by means ( y\r batt]y1 make an electric bell r+4 ,exam9e ! bell & trace ! curr5t ?r\gh x4 ,notice h[ ! curr5t passes ar\nd two iron b>s & magnetizes !m1 z x did 9 ! telegraph in/rum5t4 ,notice t ! circuit is complet$ ?r\gh a little metal atta*m5t on ! base ( ! clapp]1 & t :5 ! clapp] is pull$ t[>d ! electromagnet ! circuit is brok54 ,! iron b>s are !n no long] magnetiz$4 ,notice t a spr+ pulls ! clapp] back into place z soon z ! iron /ops attract+ x4 ,?is completes ! circuit aga9 & ! clapp] is pull$ d[n4 ,t breaks ! circuit & ! clapp] spr+s back4 ,see h[ ?is con/ant mak+ & break+ ( ! circuit causes ! bell clapp] to fly back & =?4 ,illu/ration3 ,,fig4 #adc4 ,! bell is rung by electromagnets4 ,! electric bell1 l ! telephone & telegraph1 works on ! simple pr9ciple t electricity fl[+ ?r\gh a wire t is wrapp$ ar\nd & ar\nd a piece ( iron w turn t piece ( iron into a magnet z long z ! electricity fl[s4 ,,! ,,electric ,,motor4 ,! motor ( a /reet c> is a /ill m complicat$ c>ry+ out ( ! same pr9ciple4 ,9 ! next exp]im5t y w see ! work+ ( a motor4 ,,exp]im5t #gi4 ,connect ! wires f ! laboratory batt]y to ! two b9d+ po/s ( ! toy motor1 & make ! motor run4 ,exam9e ! motor & see t x is made ( sev]al electromagnets :i* keep attract+ ea* o!r ar\nd & ar\nd4 ,motors1 & !re=e all ?+s t are mov$ by electricity1 includ+ trolley c>s & electric railways1 subm>9es :ile subm]g$1 electric automobiles1 electric sew+ ma*9es1 electric vacuum clean]s1 & electric play]-pianos1 are mov$ by magnetiz+ a piece ( iron & lett+ ?is pull on ano!r piece ( iron4 ,& ! iron is magnetiz$ by lett+ a curr5t ( electricity fl[ ar\nd & ar\nd x4 ,illu/ration3 ,,fig4 #add4 ,a toy electric motor t goes4 ,! mak+ ( v>i\s k9ds ( electromagnets & putt+ curr5ts ( electricity to "w is becom+ "o ( ! great indu/ries ( mank9d4 ,wat]falls are be+ hit*$ up to dynamos ev]y:]e1 & ! wat] p[] t once turn$ ! mill :eels n[ turns millions ( coils ( wire betwe5 ! poles ( p[]ful magnets4 ,! curr5t g5]at$ 9 ?is way is us$ = all k9ds ( "w--n only = furni%+ light to cities1 & cook+ meals1 heat+ homes1 & iron+ clo!s1 b = runn+ p[]ful motors 9 factories1 = driv+ int]urban tra9s swiftly across ! c\ntry1 = c>ry+ p back & =? to "w 9 city /reet c>s1 = lift+ great pieces ( iron & /eel 9 ! y>ds :]e huge electromagnets are us$1--= c\ntless pieces ( "w 9 all p>ts ( ! globe4 ,yet ! use ( electricity is /ill only 9 its beg9n+4 ,trem5d\s am\nts ( wat] p[] are /ill runn+ to wa/e2 !re is almo/ no limit to ! am\nt ( electricity we %all be able to g5]ate z we use ! _w's wat] p[] to turn our dynamos4 ,illu/ration3 ,,fig4 #ade4 ,an electric motor ( comm]cial size4 ,,application #fb4 ,expla9 h[ press+ a telegraph key c make ano!r in/rum5t click hundr$s ( miles away1 & h[ y c he> ov] ! telephone4 ,is x vibrations ( s\nd or ( electricity t g ?r\gh ! telephone wire1 or does y\r voice travel ov] x1 or does ! wire itself vibrate8 ,expla9 h[ electricity c make a c> g4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cga4 ,:5 a fuse bl[s out1 y c get no light4 #cgb4 ,if y lay y\r e> on a desk1 y he> ! s\nds 9 ! room cle>ly4 #cgc4 ,if y t\* a live wire ) wet h&s1 y get a mu* worse %ock ?an if y t\* x ) dry h&s4 #cgd4 ,a p>k music /& is back$ by a s\nd+ bo>d4 #cge4 ,! clapp] ( an electric bell is pull$ aga9/ ! bell :5 y pu% ! button4 #cgf4 ,a hot iron tire put on a wagon :eel fits v tightly :5 x cools4 #cgg4 ,c&y w cool m rapidly 9 a t9 plate ?an 9 a *9a plate4 #cgh4 ,:5 a trolley wire breaks & falls to ! gr\nd x melts & burns at ! po9t at :i* x t\*es ! gr\nd4 #cgi4 ,by all[+ ! electricity f ! trolley wire to fl[ d[n ?r\gh an und]gr\nd coil ( wire1 a motorman c op5 a swit* 9 ! track4 #chj4 ,! b>e ends ( ! two wires lead+ to y\r electric lamp %\ld nev] be all[$ to t\* ea* o!r4 ,,*apt] ,,n9e ,,m+l+ ,,( ,,molecules ,,section #da4 ,solutions & emulsions4 ,h[ does soap make y\r h&s clean8 ,:y w gasol9e take a grease spot out ( y\r clo!s8 ,if we 7 to g back to our conv5i5t imag9>y swit*bo>d to turn (f ano!r law1 we %\ld f9d ne> ! heat swit*es1 & n f> f ! *emi/ry ones1 a swit* label$ ,,solution4 ,suppose we turn$ x (f3 ,! fi%es 9 ! sea are among ! fir/ creatures to be surpris$ by our action4 ,= in/antly all ! salt 9 ! ocean drops to ! bottom l s mu* s&1 & mo/ salt-wat] fi%es soon p]i% 9 ! fre% wat]4 ,if "s "o is ab\t to dr9k a cup ( tea & has sweet5$ x j to 8 ta/e1 y c imag9e 8 amazem5t :51 br++ x to 8 lips1 he f9ds himself dr9k+ ta/eless1 :ite1 milky wat]4 ,d[n 9 ! bottom ( ! cup is a s$im5t ( sug>1 l s mu* f9e gravel1 ) a br[ni% du/ ( tea cov]+ x4 ,to see :e!r or n ! tr\ble is ) ! sug> itself1 he may take "s sug> out ( ! b[l & ta/e x1--x is j l :ite s&4 ,wond]+ :at has happ5$1 & :e!r he or ! sug> is at fault1 he rea*es = ! v9eg> cruet4 ,! v9eg> is no long] cle>1 b is a colorless liquid ) t9y specks ( br[n float+ ab\t 9 x4 ,ta/+ x1 he ?9ks x mu/ be du/y wat]4 ,salt1 pepp]1 mu/>d1 onions1 or any?+ he eats1 is absolutely ta/eless1 al?\gh "s ( ! ?+s smell z /rong z ev]4 ,to tell ! tru?1 ,i d\bt if ! man has a *ance to d all ( ?is exp]im5t+4 ,= ! salt 9 8 blood turns to solid h>d gra9s1 & ! dissolv$ food 9 ! blood turns to du/like p>ticles4 ,8 blood fl[s ?r\gh him1 a muddy /ream ( /]ile wat]4 ,! cells ( 8 body get no food1 & ev5 be=e !y miss ! food1 mo/ ( ! cells %rivel to drops ( muddy wat]4 ,! :ole man collapses4 ,plants are z badly (f4 ,! life-giv+ sap turns to wat] ) specks ( ! "o-"t n\ri%m5t float+ uselessly ?r\gh x4 ,mo/ plant cells1 l ! cells 9 ! man1 turn to wat]1 ) fib]s & du/ flecks mak+ x cl\dy4 ,)9 a few seconds !re is n a liv+ ?+ left 9 ! _w1 & ! saltless waves da% up on a b>r5 %ore4 ,probably we _h bett] let ! ,,solution swit* alone1 aft] all4 ,in/ead1 "h are a c\ple ( exp]im5ts t w help to make cle> :at happ5s :5 any?+ dissolves to make a solution4 ,,exp]im5t #hj4 ,fill a te/ tube "o f\r? full ( cold wat]4 ,sl[ly /ir 9 salt until no m w dissolve4 ,add half a teaspoonful m ( salt ?an w dissolve4 ,dry ! outside ( ! te/ tube & heat ! salty wat] ov] ! ,buns5 burn]4 ,w hot wat] dissolve ?+s m readily or less readily ?an cold8 ,:y d y wa% di%es 9 hot wat]8 ,,exp]im5t #ha4 ,fill a te/ tube "o f\r? full ( any k9d ( oil1 & "o f\r? full ( wat]4 ,hold y\r ?umb ov] ! top ( ! te/ tube & %ake x h>d = a m9ute or two4 ,n[ look at x4 ,p\r x out1 & %ake "s prep>$ cleans] into ! te/ tube1 add+ a little m wat]4 ,%ake ! te/ tube ?or\ghly & r9se4 ,put x away clean4 ,:5 y %ake ! oil ) ! wat]1 ! oil breaks up into t9y droplets4 ,^! droplets are s small t !y reflect ! light t /rikes !m & s look :ite1 or pale yell[4 ,?is milky mixture is call$ an emulsion4 ,milk is an emulsion2 !re are t9y droplets ( butt] fat & o!r sub/ances scatt]$ all ?r\gh ! milk4 ,! butt] fat is n dissolv$ 9 ! re/ ( ! milk1 & ! oil is n dissolv$ 9 ! wat]4 ,b ! droplets may be s small t an emulsion acts almo/ exactly l a solution4 ,illu/ration3 ,,fig4 #adf4 ,w heat+ ! wat] make m salt dissolve8 ,b :5 y %ake or /ir salt or sug> 9 wat]1 ! p>ticles divide up into small] & small] pieces1 until probably ea* piece is j a s+le molecule ( ! salt or sug>4 ,& ^! molecules get into ! spaces betwe5 ! wat] molecules & b\nce ar\nd among !m4 ,!y !re=e act l ! wat] & let ! light ?r\gh4 ,?is is a solution4 ,! salt or sug> is dissolv$ 9 ! wat]4 ,any liquid mixture :i* rema9s cle> is a solution1 no matt] :at ! color4 ,mo/ r$ ink1 mo/ blue+1 cle> c(fee1 tea1 & ocean wat] are solutions4 ,if a liquid is cle>1 no matt] :at ! color1 y c be sure t :atev] ?+s may be 9 x are dissolv$4 ,illu/ration3 ,,fig4 #adg4 ,w ! volume be d\bl$ :5 ! alcohol & wat] are p\r$ toge!r8 ,,exp]im5t #hb4 ,p\r alcohol into a te/ tube 7squ>e-bottom$ te/ tubes are be/ = ?is exp]im5t71 /&+ ! tube up beside a rul]4 ,:5 ! alcohol is j #a in* high 9 ! tube1 /op p\r+4 ,put exactly ! same am\nt ( wat] 9 ano!r te/ tube ( ! same size4 ,:5 y p\r !m toge!r1 h[ _m in*es high d y ?9k ! mixture w be8 ,p\r ! wat] into ! alcohol1 %ake ! mixture a little1 & measure to see h[ high x comes 9 ! te/ tube4 ,did y notice ! w>m? :5 y %ook ! tube8 ,if y use d5atur$ alcohol1 y are likely to h an emulsion z a result ( ! mix+4 ,! alcohol "p ( ! d5atur$ alcohol dissolves 9 ! wat] well en\gh1 b ! d5atur+ sub/ance 9 ! alcohol w n dissolve 9 wat]2 s x =ms t9y droplets t make ! mixture ( alcohol & wat] cl\dy4 ,! purpose ( ?is exp]im5t is to %[ t ! molecules ( wat] get into ! spaces betwe5 ! molecules ( alcohol4 ,x is z if y 7 to add a pail ( pebbles to a pail ( apples4 ,! pebbles w\ld fill 9 betwe5 ! apples1 & ! mixture w\ld n ne>ly fill two pails4 ,! mo/ important diff]5ce betwe5 a solution & an emulsion is t ! p>ticles 9 an emulsion are v mu* l>g] ?an ^? 9 a solution2 b = practical purposes t (t5 does n make mu* diff]5ce4 ,y dissolve a grease spot f y\r clo!s ) gasol9e2 y make an emulsion :5 y take x (f ) soap & wat]2 b by ei!r me?od y remove ! spot4 ,y dissolve "p ( ! c(fee or tea 9 boil+ wat]2 y make an emulsion ) cocoa2 b 9 bo? cases ! flavor is di/ribut$ ?r\gh ! liquid4 ,milk is an emulsion1 v9eg> is a solution2 b 9 bo?1 ! p>ticles are s ?or\ghly mix$ ) ! wat] t ! flavor is ! same ?r\gh\t4 ,!re=e 9 work+ out inf]5ces t are expla9$ 9 t]ms ( solutions & emulsions1 x is n especially important = y to decide :e!r y h a solution or an emulsion if y "k t x is "o or ! o!r4 ,,h[ ,,preci\s ,,/ones ,,are ,,=m$4 ,color$ glass is made by dissolv+ color+ matt] 9 ! glass :ile x is molt54 ,rubies1 sapphires1 em]alds1 topazes1 & ame?y/s 7 color$ 9 ! same way1 b by nature4 ,:5 ! "p ( ! e>? :]e !y are f\nd 0 hot en\gh to melt /one1 ! liquid ruby or sapphire or em]ald1 or :atev] ! /one 0 to be1 happ5$ to be ne> "s color+ matt] t dissolv$ 9 x & gave x color4 ,sev]al ( ^! /ones are made ( exactly ! same k9d ( mat]ial1 b diff]5t k9ds ( color+ matt] dissolv$ 9 !m :5 !y 7 melt$4 ,_m articles are mu* us$ *iefly because !y are good emulsifi]s or good solv5ts 7dissolve ?+s well74 ,soap is a fir/-rate emulsifi]2 wat] is ! be/ solv5t 9 ! _w2 b x w n dissolve oil & gummy ?+s suffici5tly to be ( use :5 we want !m dissolv$4 ,turp5t9e1 alcohol1 & gasol9e f9d "o ( _! *ief uses z solv5ts = gums & oils4 ,almo/ all clean+ is simply a process ( dissolv+ or emulsify+ ! dirt y want to get rid (1 & wa%+ x away ) ! liquid4 ,d n =get t heat helps to dissolve mo/ ?+s4 ,,application #fc4 ,expla9 :y clo!s are wa%$ 9 hot suds2 :y sug> disappe>s 9 hot c(fee or tea2 :y x does n disappe> z quickly 9 cold lemonade2 :y y _c see ?r\gh milk z y c ?r\gh wat]4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cha4 ,a k9d ( lamp bracket is made ) a rubb] cup4 ,:5 y press ?is cup aga9/ ! wall or aga9/ a piece ( furniture & exhau/ ! air f ! cup1 ! cup /icks fa/ to ! wall & supports ! lamp bracket4 #chb4 ,y c take a vasel9e /a9 out ) k]os5e4 #chc4 ,if ! two poles ( an electric batt]y are connect$ ) a copp] wire1 ! batt]y soon becomes dis*>g$4 #chd4 ,electric bells h iron b>s w\nd ar\nd & ar\nd ) insulat$ copp] wire4 #che4 ,piano keys may be clean$ ) alcohol4 #chf4 ,l9em5 work+ ) live wires we> heavy rubb] gloves4 #chg4 ,crayon w n write on ! smoo?1 glaz$ p>ts ( a blackbo>d4 #chh4 ,v>ni% & %ellac may be ?9n$ ) alcohol4 #chi4 ,filt]+ w take mud out ( wat]1 b x w n remove salt4 #cij4 ,expla9 :y only "o wire is ne$$ to telegraph betwe5 two /ations4 ,,section #db4 ,cry/als4 ,h[ is rock c&y made8 ,:y is !re sug> ar\nd ! m\? ( a syrup jug8 ,h[ are jewels =m$ 9 ! e>?8 ,y c le>n h[ cry/als are =m$--& _m gems & rock c&y & ! sug> on a syrup jug are all cry/als--by mak+ "s4 ,try ?is exp]im5t3 ,,exp]im5t #hc4 ,fill a te/ tube "o f\r? full ( p[d]$ alum2 cov] ! alum ) boil+ wat]2 hold ! tube ov] a flame s t ! mixture w boil g5tly2 & sl[ly add boil+-hot wat] until all ( ! alum is dissolv$4 ,d n add any m wat] ?an y h to1 & keep /irr+ ! alum ) a glass rod :ile y are add+ ! wat]4 ,p\r half ( ! solution into ano!r te/ tube = ! next exp]im5t4 ,hang a /r+ 9 ! fir/ te/ tube s t x t\*es ! bottom ( ! tube4 ,set x aside to cool1 uncov]$4 ,! next day exam9e ! /r+ & ! bottom ( ! tube4 ,,exp]im5t #hd4 ,:ile ! solution ( alum 9 ! second te/ tube 7,exp]im5t #hc7 is /ill hot1 hold ! tube 9 a pan ( cold wat] & %ake or /ir x until x cools4 ,:5 :ite specks appe> 9 ! cle> solution1 p\r (f z mu* ( ! cle> "p ( ! liquid z y c2 !n p\r a little ( ! re/ on a glass slide1 & exam9e ! specks "u a microscope4 ,illu/ration3 ,,fig4 #adh4 ,alum cry/als4 ,9 bo? ( ! above exp]im5ts1 ! hot wat] 0 able to dissolve m ( ! alum ?an ! cold wat] c\ld possibly hold4 ,s :5 ! wat] cool$ x c\ld no long] hold ! alum 9 solution4 ,!re=e "p ( ! alum turn$ to solid p>ticles4 ,:5 ! /r+ 0 9 ! cool+ liquid1 x attract$ ! p>ticles ( alum z !y cry/alliz$ out ( ! solution4 ,! =ce ( adhesion drew ! ne>-by molecules to ! /r+1 !n ^! drew ! next1 & ^! drew m1 & s on until ! cry/als 7 =m$4 ,b :5 y kept /irr+ ! liquid :ile x cool$1 ! cry/als nev] _h "t to gr[ l>ge be=e !y 7 jo/l$ ar\nd to "s o!r "p ( ! liquid or 7 brok5 by y\r /irr+ rod4 ,!re=e !y 7 small in/ead ( l>ge4 ,/irr+ or %ak+ a solution w always make cry/als =m m quickly1 b x w also make !m small]4 ,,h[ ,,rock ,,c&y ,,is ,,made4 ,rock c&y is made by hang+ a /r+ 9 a /rong sug> solution or syrup & lett+ ! wat] evaporate sl[ly until !re is n en\gh wat] to hold all ! sug> 9 solution4 ,!n ! sug> cry/als ga!r sl[ly ar\nd ! /r+1 =m+ ! l>ge1 cle> pieces ( rock c&y4 ,! sug> ar\nd ! m\? ( a syrup jug is =m$ 9 ! same way4 ,y always get cry/allization :5 y make a liquid too cool to hold ! solid ?+ 9 solution1 or :5 y evaporate s mu* ( ! liquid t !re is n en\gh left to keep ! solid ?+ dissolv$4 ,:5 y make fudge1 ! sug> =ms small cry/als z ! liquid cools4 ,:5 a boat has be5 on ! ocean1 salt cry/als =m on ! sails :5 ! spray t has wet !m evaporates4 ,b cry/als may =m also 9 ! air4 ,!re is always "s moi/ure 9 ! air1 & :5 x becomes v cold1 "s ( ?is moi/ure =ms cry/als ( ice4 ,if !y =m up 9 ! cl\ds1 !y fall z sn[4 ,if !y =m ar\nd blades ( grass or on ! sidewalk1 z ! alum cry/als =m$ on ! /r+1 we h fro/4 ,/ill ano!r place t cry/als occur is 9 ! e>?4 ,:5 ! rocks 9 ! e>? 7 hot en\gh to be melt$ & !n began to cool1 c]ta9 sub/ances 9 ! rocks cry/alliz$4 ,"s ( ^! cry/als t are especially h>d & cle> con/itute preci\s & semi-preci\s /ones4 ,,application #fd4 ,expla9 :y y beat fudge z x cools2 :y ! pap] ar\nd butt] becomes encru/$ ) salt if x is expos$ to ! air = "s "t4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #cia4 ,dynamos h copp] bru%es to lead ! curr5t f ! coils ( wire to ! l9e wires4 #cib4 ,a megaphone makes ! voice c>ry f>!r ?an usual4 #cic4 ,copp] wire is us$ to conduct electricity1 al?\gh iron wire co/s mu* less4 #cid4 ,a flute gives notes t diff] 9 pit* accord+ to ! /ops t are op5$4 #cie4 ,!re are usually solid pieces ( sug> ar\nd ! m\? ( a syrup j>4 #cif4 ,y c beat eggs quickly ) a ,dov] egg beat]4 #cig4 ,:5 ocean wat] /&s 9 %all[ op5 tanks = "s "t1 salt beg9s to =m be=e ! wat] has all evaporat$4 #cih4 ,9 a c(fee p]colator ! boil+ wat] goes up ?r\gh a tube4 ,z ?is wat] drips back ?r\gh ! gr\nd c(fee beans1 x becomes br[n & flavor$1 & ! c(fee is made4 #cii4 ,k]os5e w clean (f ! rim ( soap & grease t =ms 9 ba?tubs4 #djj4 ,beat+ cake fro/+ or c&y causes x to sug>4 ,,section #dc4 ,diffusion4 ,h[ does food get into ! blood8 ,:y c y s quickly smell gas t is escap+ at ! opposite side ( a room8 ,on our imag9>y swit*bo>d ! ,,diffusion swit* w\ld n be safe to tamp] )4 ,x w\ld be ne> ! ,,solution swit*1 & almo/ z dang]\s4 ,= if y 7 to make diffusion cease 9 ! _w1 ! dissolv$ food & oxyg5 9 y\r blood w\ld d no good2 x c\ld n get out ( ! blood vessels or into ! cells ( y\r body4 ,y might brea! all y lik$1 b brea?+ w\ld n help y2 ! air c\ld n get ?r\gh ! walls ( y\r lungs into ! blood4 ,plants w\ld beg9 to )] & droop1 al?\gh !y w\ld n die q z quickly z animals & fi%es & p4 ,b no sap c\ld ent] _! roots & none c\ld pass f cell to cell4 ,! plants w\ld be z little able to brea! ?r\gh _! leaves z we ?r\gh our lungs4 ,if gas escap$ 9 ! room :]e y 71 y c\ld n smell x ev5 if y /ay$ alive long en\gh to try2 ! gas w\ld rise to ! top ( ! room & /ay !re4 ,all gases & all liquids w\ld /ay z !y 71 & nei!r w\ld ev] =m mixtures4 ,x w\ld n make s mu* diff]5ce 9 ! dead p>ts ( ! _w if diffusion ceas$2 ! rocks1 m\nta9s1 e>?1 & sea w\ld n be *ang$ at all at fir/4 ,to be sure1 ! riv]s :]e !y fl[$ into ! oceans w\ld make big spaces ( saltless wat]2 & :5 wat] evaporat$ f ! ocean ! vapor w\ld pu% aside ! air & /ay 9 a lay] ov] ! ocean1 in/ead ( mix+ ) ! air & ris+ to great heights4 ,b ! real disa/] w\ld be to liv+ ?+s4 ,all ( !m w\ld be smo!r$ & />v$ to dea? z soon z diffusion ceas$4 ,"h is an exp]im5t t %[s h[ gases diffuse3 ,,exp]im5t #he4 ,take two te/ tubes ) m\?s ( ! same size s t y c fit !m snugly aga9/ ea* o!r :5 y want to4 ,fill "o to ! brim ) wat] & hold y\r ?umb or a piece ( c>dbo>d ov] its m\? :ile y place x upside d[n 9 a pan ( wat]4 ,take ! free end ( a rubb] tube t is atta*$ to a gas pipe & put x into ! te/ tube a %ort di/ance1 s t ! gas w g up into ! tube1 z %[n 9 ,figure #adi4 ,n[ turn on ! gas g5tly4 ,:5 all ! wat] has be5 =c$ out ( ! tube & ! gas bubbles beg9 to come up on ! outside1 turn (f ! gas4 ,put a piece ( c>dbo>d1 ab\t an in* or s squ>e1 ov] ! m\? ( ! tube s t no air c get into x1 & take ! tube out ( ! wat]1 keep+ ! m\? d[n & cov]$4 ,br+ ! empty te/ tube1 :i* ( c\rse is full ( air1 m\? up "u ! te/ tube full ( gas1 mak+ ! m\?s ( ! two tubes meet ) ! c>dbo>d betwe5 !m1 z %[n 9 ,figure #aej4 ,n[ h "s "o pull ! c>dbo>d g5tly f betwe5 ! two te/ tubes1 s t ! m\?s ( ! tubes w be press$ aga9/ ea* o!r & s t practically no gas w escape4 ,hold !m quietly ?is way1 ! tube ( gas upp]mo/1 = n less ?an "o full m9ute by ! clock4 ,a m9ute & a half is n too mu* "t4 ,n[ h "s "o light a mat* = y1 or else g to a light$ ,buns5 burn]4 ,take ! te/ tubes ap>t g5tly & hold ! l[] "o1 :i* 0 full ( air1 ) its m\? to ! flame4 ,:at has ! gas 9 ! upp] tube done8 ,n[ hold ! flame to ! upp] te/ tube1 :i* 0 full ( gas4 ,:at happ5s8 ,has all ! gas gone out ( x8 ,illu/ration3 ,,fig4 #adi4 ,fill+ a te/ tube ) gas4 ,illu/ration3 ,,fig4 #aej4 ,! l[] te/ tube is full ( air2 ! upp]1 ( gas4 ,:at w happ5 :5 ! c>dbo>d is )drawn8 ,z y well "k1 gas is mu* light] ?an air2 y c make a balloon rise by fill+ x ) gas4 ,yet "p ( ! gas w5t d[n into ! l[] tube4 ,! explanation is t ! molecules ( gas & ^? ( air 7 fly+ ar\nd at su* a rate t _m ( ! gas molecules w5t %oot+ d[n among ! air molecules1 & _m ( ! molecules ( air w5t %oot+ up among ^? ( gas1 s t ! gas & ! air became mix$4 ,,diffusion ,,9 ,,liquids4 ,diffusion takes place 9 liquids1 z y "k4 ,= :5 y put sug> 9 c(fee or tea & d n /ir x1 al?\gh ! upp] "p ( ! tea or c(fee is n sweet5$1 ! "p ne>] ! sug> is v sweet4 ,if y %\ld let ! c(fee or tea1 ) ! sug> 9 ! bottom1 /& = a few mon?s1 x w\ld get sweet all ?r\gh4 ,diffusion is sl[] 9 liquids ?an 9 gases1 because ! molecules are s v mu* clos] toge!r4 ,,osmosis4 ,"o ( ! mo/ /rik+ & important facts ab\t diffusion is t x c take place "r ?r\gh a membrane4 ,try ?is exp]im5t3 ,,exp]im5t #hf4 ,) a rubb] b& fa/5 a piece ( p>*m5t pap]1 made into a little bag1 to ! end ( a piece ( glass tub+ ab\t #aj in*es long4 ,or make a small hole 9 "o end ( a raw egg & empty ! %ell2 !n1 to get ! h>d "p (f ! %ell1 soak x ov]night 9 /rong v9eg> or hydro*loric acid dilut$ ab\t #a to #d4 ,?is w leave a membran\s bag t c be us$ 9 place ( ! p>*m5t bag4 ,fill a tumbl] half full ( wat] color$ ) r$ ink1 & add en\gh corn/>* to make ! wat] milky4 ,p\r into ! tube en\gh ( a /rong sug> solution to fill ! membran\s bag at its base & to rise half an in* 9 ! tube4 ,put ! membran\s bag d[n into ! p9k1 milky wat]1 support+ ! tube by pass+ x ?r\gh a squ>e c>dbo>d & clamp+ x ) a spr+ clo!sp9 z %[n 9 ,figure #aea4 ,e few m9utes look to see :at is happ5+4 ,does any ( ! r$ ink pass ?r\gh ! membrane8 ,does any ( ! corn/>* pass ?r\gh8 ,?is is an example ( diffusion ?r\gh a membrane4 ,! process is call$ osmosis1 & ! pressure t =ces ! liquid up ! tube is call$ osmotic pressure4 ,x is by ?is sort ( diffusion t *icks :i* are be+ incubat$ get air1 & t gr[+ plants get food4 ,x is 9 ?is way t ! cells ( our body secure food & oxyg5 & get rid ( _! wa/es4 ,!re are no little holes 9 our blood vessels to let ! air get into !m f our lungs4 ,! air simply diffuses ?r\gh ! ?9 walls ( ! blood vessels4 ,!re are no holes f ! inte/9al tract into ! blood vessels4 ,yet ! dissolv$ food diffuses "r ?r\gh ! inte/9al wall & ?r\gh ! walls ( ! blood vessels4 ,& lat] on1 :5 x rea*es ! body cells t ne$ n\ri%m5t1 ! dissolv$ food diffuses out ?r\gh ! walls ( ! blood vessels aga9 & ?r\gh ! cell walls into ! cells4 ,wa/e is tak5 out ( ! cells into ! blood & passes f ! blood into ! lungs & kidneys by ?is same process ( diffusion4 ,s y c readily see :y ev]y?+ w\ld die if diffusion /opp$4 ,illu/ration3 ,,fig4 #aea4 ,p\r+ ! syrup into ! osmosis tube4 ,,application #fe4 ,expla9 h[ ! roots ( a plant c take 9 wat] & food :5 !re are no holes f ! outside ( ! root to ! inside2 h[ bees c smell fl[]s = a consid]able di/ance4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dja4 ,a %ell 9 ! bottom ( a teakettle ga!rs mo/ ( ! scale ar\nd x & s keeps ! scale f cak+ at ! bottom ( ! kettle4 #djb4 ,!re is oxyg5 dissolv$ 9 wat]4 ,:5 ! wat] comes 9 contact ) ! f9e blood vessels 9 a fi%'s gills1 "s ( ?is oxyg5 passes ?r\gh ! walls ( ! blood vessels into ! blood4 ,expla9 h[ x does s4 #djc4 ,asphalt becomes s(t 9 summ]4 #djd4 ,:5 ! trolley comes (f ! wire ! c> soon /ops4 #dje4 ,y _c see />s 9 ! daytime on e>?1 yet y c\ld see !m 9 ! daytime on ! airless moon4 #djf4 ,al?\gh ! c>bon dioxid y brea! out is heavi] ?an ! re/ ( ! air1 "p ( x goes up & mixes ) ! air above4 #djg4 ,on a cold day wood does n feel z cold z iron4 #djh4 ,to make mayonnaise dress+1 ! oil1 egg1 & v9eg> are ?or\ghly beat5 toge!r4 #dji4 ,a solution ( iod9 becomes /rong] if x is all[$ to /& op5 to ! air4 #daj4 ,a drop ( milk 9 a glass ( wat] cl\ds all ! wat] slightly4 ,,section #dd4 ,cl\ds1 ra91 & dew3 ,humidity4 ,:y is x t y c see y\r brea? on a cold day8 ,:]e d ra9 & sn[ come f8 ,:at makes ! cl\ds8 ,!re is wat] vapor 9 ! air all ar\nd u--invisible wat] vapor1 its molecules m+l+ ) ^? ( ! air--wat] t has evaporat$ f ! oceans & lakes & all wet places4 ,?is wat] vapor *anges into droplets ( wat] :5 x gets cool en\gh4 ,& ^? droplets ( wat] make up our cl\ds & fogs2 !y jo9 toge!r to =m our ra9 & sn[ high 9 ! air1 or ga!r z dew or fro/ on ! grass at night4 ,if ! wat] vapor %\ld sudd5ly lose its p[] ( *ang+ into droplets ( wat] :5 x cool$1--well1 let u pret5d x has lo/ ?is p[] b t any am\nt ( wat] c evaporate1 & see :at happ5s3 ,:at f9e wea!r x is6 ,!re is n a cl\d 9 ! sky4 ,z ev5+ closes 91 ! />s come out ) int5se brightness4 ,! :ole sky is gleam+ ) />s--m ?an we h ev] se5 at night be=e4 ,! next morn+ we f9d no dew or fro/ on ! grass4 ,all ! gre5 ?+s look dry4 ,z ! day goes on1 !y beg9 to wilt & )]4 ,we all wi% ! day 7 n q s f9e--a little ra9 w\ld help ?+s wond]fully4 ,n a cl\d appe>s1 h[ev]1 & we wat] z mu* ( our g>d5s z we c4 ,!y dr9k ! wat] gre$ily1 & t night1 aga9 no dew or fog1 & n ! fa9te/ cl\d or mi/ to dim ! />s4 ,& ! new day once m br+s ! blaz+ sun fur!r to p>* ! l& & plants4 ,day aft] day & night aft] night ! dr\ght gets worse4 ,! riv]s s9k l[2 brooks run dry2 ! edges ( ! lakes become m>%es4 ,! m>%es dry out to h>d5$ mud4 ,! dry leaves ( ! trees ru/le & crumble4 ,all ! animals & wood creatures ga!r ar\nd ! muddy pools t once 7 lakes or riv]s4 ,p beg9 sav+ wat] & buy+ x & sell+ x z ! mo/ preci\s ( articles4 ,z ! mon?s g by1 w9t] freezes ! few pools t rema94 ,no sn[ falls4 ,liv+ creatures die by ! t5s ( ?\s&s4 ,b ! w9t] is less cold ?an usual1 because !re is n[ s mu* wat] vapor 9 ! air t x acts l a great blanket hold+ 9 ! e>?'s heat4 ,) spr+ no %[]s come4 ,! dead trees s5d =? no buds4 ,no birds h]ald ! com+ ( w>m wea!r4 ,! cont95ts ( ! _w h become va/1 un9habitable des]ts4 ,p h all mov$ to ! %ores ( ! ocean1 :]e _! *emi/s are extract+ salt f ! wat] 9 ord] to give !m some?+ to dr9k4 ,by us+ ?is saltless wat] !y c irrigate ! l& ne> ! oceans & gr[ "s food to live on4 ,ea* cont95t is encircl$ by a /rip ( irrigat$ l& & d5sely populat$ cities close to ! wat]'s edge4 ,x is _m ye>s be=e ! oceans disappe>4 ,b 9 "t !y too are trans=m$ into wat] vapor1 & no m life z we "k x is possible 9 ! _w4 ,! e>? has become a great rocky & s&y ball1 :irl+ ?r\gh space1 lifeless & utt]ly dry4 ,t :i* prev5ts ?is f really happ5+ is v simple3 ,9 ! _w z x is1 wat] vapor cond5ses & *anges to drops ( wat] :5ev] x gets cool en\gh4 ,,h[ ,,wat] ,,vapor ,,gets ,,into ,,! ,,air4 ,! wat] vapor gets into ! air by evaporation4 ,:5 we say t wat] evaporates1 we mean t x *anges into wat] vapor4 ,z y already "k1 x is heat t makes wat] evaporate2 t is :y y hang wet clo!s 9 ! sun or by ! fire to dry3 y want to *ange ! wat] 9 !m to wat] vapor4 ,! sun does n suck up ! wat] f ! ocean1 z "s p say2 b x w>ms ! wat] & turns "p ( x to vapor4 ,:at happ5s d[n among ! molecules :5 wat] evaporates is ?is3 ,! heat makes ! molecules dance ar\nd fa/] & fa/]2 !n ! ones ) ! swifte/ motion ne> ! top %oot (f into ! air4 ,! molecules t h %ot (f into ! air make up ! wat] vapor4 ,! wat] vapor is entirely invisible4 ,no matt] h[ mu* ( x !re is1 y _c see x4 ,! wea!r is j z cle> :5 !re is a great deal ( wat] vapor 9 ! air z :5 !re is v little1 z long z none ( ! vapor cond5ses4 ,,h[ ,,cl\ds ,,are ,,=m$4 ,b :5 wat] vapor cond5ses1 x =ms into extremely small drops ( real wat]4 ,ea* ( ^! drops is s small t x is usually impossible to see "o2 !y are s t9y t y c\ld lay ab\t #cjjj ( !m side by side 9 "o in*6 ,yet1 small z !y are1 :5 !re are _m ( !m !y become di/9ctly visible4 ,we see !m float+ ar\nd u sometimes & call !m fog or mi/4 ,& :5 !re are millions ( !m float+ 9 ! air high above u1 we call !m a cl\d4 ,! reason cl\ds =m s high 9 ! air is ?is3 ,:5 air or any gas exp&s1 x cools4 ,d y rememb] ,exp]im5t #ca1 :]e y let ! gas f a tank exp& into a wet te/ tube & x became s cold t ! wat] on ! te/ tube froze8 ,well1 x is mu* ! same way ) ris+ air4 ,:5 air rises1 !re is less air above x to keep x compress$2 s x exp&s & cools4 ,!n ! wat] vapor 9 x cond5ses into droplets ( wat]1 & ^! =m a cl\d4 ,ea* droplet =ms a ga!r+ place = m cond5s+ wat] vapor1 & !re=e gr[s4 ,:5 ! droplets ( wat] 9 a cl\d are v close toge!r1 "s may be jo/l$ aga9/ "o ano!r by ! w9d4 ,& :5 !y t\* ea* o!r1 !y /ick toge!r1 =m+ a l>g] drop4 ,:5 a drop gr[s l>ge en\gh x beg9s to fall ?r\gh ! cl\d1 ga!r+ up ! small droplets z x goes4 ,by ! "t x gets out ( ! cl\d x has gr[n to a full-siz$ ra9drop1 & falls to e>?4 ,! complete /ory ( ra91 !n1 is ?is3 ,,h[ ,,ra9 ,,is ,,caus$4 ,! surface ( ! oceans & lakes is w>m$ by ! sun4 ,! wat] evaporates1 turn+ to invisible wat] vapor4 ,?is wat] vapor m+les ) ! air4 ,aft] a :ile ! air is caught 9 a ris+ curr5t & swept up high1 c>ry+ ! wat] vapor ) x4 ,z ! air rises1 !re is less air above x to press d[n on x2 s x exp&s4 ,:5 air exp&s x cools1 & ! wat] vapor :i* is m+l$ ) x likewise cools4 ,:5 ! wat] vapor gets cool en\gh x cond5ses1 *ang+ to myriads ( extremely small drops ( wat]4 ,^! make a cl\d4 ,a w9d comes along2 t is1 ! air 9 :i* ! cl\d is float+ moves4 ,! w9d c>ries ! cl\d along ) x4 ,m ris+ air1 full ( evaporat$ wat] f ! ocean1 jo9s ! cl\d & cools1 & ! wat] =ms into m t9y droplets4 ,! droplets get s close toge!r t !y %ut out ! sun's light f ! e>?1 & p say t ! sky is d>k5+4 ,mean:ile "s ( ! droplets beg9 to t\* ea* o!r & to /ick toge!r4 ,little by little ! drops gr[ bigg] by jo9+ toge!r4 ,pretty soon !y get s big & heavy t !y c no long] float high 9 ! air1 & !y fall to ! gr\nd z ra94 ,"p ( ! ra9 soaks into ! gr\nd4 ,"s ( x gradually seeps d[n ?r\gh ! gr\nd to an und]gr\nd /ream4 ,?is has its outlet 9 a spr+ or well1 or 9 an op5 lake or ! ocean4 ,b ! ra9 does n all soak 94 ,aft] ! /orm1 "s ( ! wat] aga9 evaporates f ! top ( ! gr\nd & mixes ) ! w>m air1 & x goes ?r\gh ! same r\nd4 ,o!r ra9drops jo9 on ! gr\nd to =m rivulets t trickle along until !y meet & jo9 o!r rivulets2 & all g on toge!r z a brook4 ,! brook jo9s o!rs until ! brooks =m a riv]2 & ! riv] fl[s into a lake or into ! ocean4 ,!n aga9 ! sun w>ms ! surface ( ! ocean or lake2 ! wat] evaporates & mixes ) ! air1 :i* rises1 exp&s1 & cools2 ! droplets =m & make cl\ds2 ! droplets jo91 =m+ big drops1 & !y fall once m z ra94 ,! ra9 soaks into ! gr\nd or runs (f 9 rivulets1 & soon] or lat] x is once m evaporat$4 ,& s ! cycle is repeat$ aga9 & aga94 ,& all ?is is acc\nt$ = by ! simple fact t :5 wat] evaporates its vapor m+les ) ! air2 & :5 ?is vapor is suffici5tly cool$ x cond5ses & =ms droplets ( wat]4 ,,! ,,b>omet]4 ,9 pr$ict+ ! wea!r a great deal ( use is made ( an in/rum5t call$ ! b>omet]4 ,! b>omet] %[s h[ h>d ! air ar\nd x is press+4 ,if ! air is press+ h>d1 ! m]cury 9 ! b>omet] rises4 ,if ! air is n press+ h>d ! m]cury s9ks4 ,j be=e a /orm1 ! air usually does n press s h>d on ?+s z at o!r times2 s usually1 j be=e a /orm1 ! m]cury 9 ! b>omet] is l[] ?an 9 cle> wea!r4 ,y w und]/& ! b>omet] bett] aft] y make "o4 ,"h are ! directions = mak+ a b>omet]3 ,,exp]im5t #hg4 ,to be done by ! class ) ! aid ( ! tea*]4 ,use a piece ( glass tub+ n less ?an #cb in*es long1 seal$ at "o end4 ,fill ?is tube to ! brim ) m]cury 7quicksilv]71 by p\r+ ! m]cury into x ?r\gh a pap] funnel4 ,h ! seal$ end ( ! tube 9 a cup1 to cat* any m]cury t spills4#g ,:5 ! tube is full1 p\r m]cury into ! cup until !re is at lea/ half an in* ( x at ! bottom4 ,n[ put y\r =ef+] v tightly ov] ! op5 end ( ! tube1 take hold ( ! seal$ end ) y\r o!r h&1 & turn ! tube ov]4 ,l[] ! op5 end1 ) y\r f+] ov] x1 into ! cup4 ,:5 ! m]cury 9 ! cup completely cov]s y\r f+] & ! end ( ! tube1 remove y\r f+] c>efully s t no air c get up into ! tube ( m]cury4 ,let ! op5 end ( ! tube re/ g5tly on ! bottom ( ! cup1 & hold ! tube upright ) y\r h& or by clamp+ x to a r+ /&4 ,hold a y>d/ick or met] /ick beside ! tube1 rememb]+ to keep ! tube /raight up & d[n4 ,measure accurately ! height ( ! m]cury column f ! surface ( ! m]cury 9 ! cup4 ,!n g to ! regul> b>omet] hang+ on ! wall1 & read x4 ,footnote #g3 ,if m]cury spills on ! floor or table dur+ ?is exp]im5t1 ga!r x all into a piece ( pap] by bru%+ ev5 ! t9y droplets toge!r ) a s(t bru%2 squeeze x ?r\gh a t[el into a cup to clean x4 ,x is exp5sive2 s try n to lose any ( x4 ,! reason y\r b>omet] may n read exactly ! same z ! exp5sive laboratory in/rum5t is t a little air & wat] vapor /ick to ! inside ( ! tube & rise into ! vacuum above ! m]cury2 also1 ! tube may n be q /raight up & d[n4 ,o!rwise ! read+s w\ld be ! same4 ,illu/ration3 ,,fig4 #aeb4 ,fill+ ! b>omet] tube ) m]cury4 ,( c\rse y und]/& :at holds ! m]cury up 9 ! tube4 ,if y c\ld put ! cup ( m]cury into a vacuum1 ! m]cury 9 ! tube w\ld s9k d[n into ! cup4 ,b ! pressure ( ! air on ! surface ( ! m]cury 9 ! cup keeps ! m]cury f fl[+ out ( ! tube & s leav+ a vacuum 9 !re4 ,if ! air pu%es d[n h>d on ! m]cury 9 ! cup1 ! m]cury w /& high 9 ! tube4 ,?is is call$ high pressure4 ,if ! air does n press h>d on ! m]cury 9 ! cup1 ! m]cury /&s l[ 9 ! tube4 ,?is is call$ l[ pressure4 ,illu/ration3 ,,fig4 #aec4 ,inv]t+ ! fill$ tube 9 ! cup ( m]cury4 ,,h[ ,,wea!r ,,is ,,=eca/4 ,wea!r =eca/]s make a great deal ( use ( ! b>omet]1 = /orms are usually accompani$ by l[ pressure1 & cle> wea!r ne>ly always goes ) high pressure4 ,! reason /orms are usually accompani$ by l[ pressure is ?is3 ,a /orm is almo/ always due to ! ris+ ( air1 = ! ris+ air exp&s & cools1 & if !re is mu* wat] vapor 9 x1 ?is cond5ses :5 x cools & =ms cl\ds & ra94 ,n[ air rises only :5 !re is comp>atively little pressure f above4 ,!re=e1 be=e & dur+ a /orm !re is n s mu* pressure on ! m]cury ( ! b>omet] & ! b>omet] is l[4 ,cle> wea!r1 on ! o!r h&1 is (t5 ! result ( air be+ compress$1 = compress+ air w>ms x4 ,:5 air is be+ w>m$1 ! wat] vapor 9 x w n cond5se2 s ! air rema9s cle>4 ,b :5 ! air is be+ compress$1 x presses h>d on ! m]cury ( ! b>omet]2 ! pressure is high1 & ! m]cury 9 ! b>omet] rises high4 ,!re=e :5 ! m]cury 9 ! b>omet] is ris+1 ! wea!r is usually cle>4 ,illu/ration3 ,,fig4 #aed4 ,f9d+ ! pressure ( ! air by measur+ ! height ( ! m]cury 9 ! tube4 ,^! two /atem5ts are true only 9 a v g5]al way1 h[ev]4 ,if wea!r =eca/]s _h only _! own b>omet]s to g by1 !y w\ld n be ( mu* value2 = "o ?+1 !y c\ld n tell u t a /orm 0 com+ mu* be=e x rea*$ u4 ,b !re are wea!r /ations all ov] ! civiliz$ _w1 & !y keep 9 t\* ) ea* o!r by telegraph4 ,x is kn[n t /orms travel f we/ to ea/ 9 our "p ( ! _w4 ,if "o wea!r man reports a /orm at 8 /ation1 & tells h[ 8 b>omet] /&s1 ! wea!r m5 to ! ea/ ( him "k t ! /orm is com+ _! way4 ,f sev]al su* reports ! wea!r m5 to ! ea/ c tell h[ fa/ ! /orm is travel+ & exactly :i* way x is go+4 ,!n !y c tell :5 x w rea* _! /ation & c make ! correct pr$iction4 ,illu/ration3 ,,fig4 #aee4 ,! k9d ( m]cury b>omet] t y buy4 ,wea!r m5 d n h to wait = an actual /orm to be report$4 ,if ! reports f ! we/ %[ t ! air is ris+ z x swirls along--t is1 if ! b>omet] read+s 9 ! we/ are l[--!y "k t ?is l[-pressure air is approa*+ !m4 ,& !y "k t l[ pressure usually means air t is ris+ & cool+ & !re=e likely to drop its moi/ure4 ,9 ! same way1 if ! b>omet]s to ! we/ %[ high pressure1 ! ea/]n wea!r m5 "k t ! air t is bl[+ t[>d !m is be+ compress$ & w>m$1 & is !re=e n at all likely to drop its moi/ure2 s !y pr$ict fair wea!r4 ,! wea!r man is n ev] c]ta9 ( 8 =eca/s1 h[ev]4 ,sometimes ! air w beg9 to rise j be=e x gets to him4 ,!n !re may be a %[] ( ra9 :5 he has pr$ict$ fair wea!r4 ,or sometimes ! air t has be5 ris+ to ! we/1 & :i* has made him pr$ict bad wea!r1 may /op ris+2 ! /orm may be ov] be=e x rea*es 8 /ation4 ,!n 8 pr$iction ( bad wea!r is wrong4 ,or sometimes ! /orm unexpect$ly *anges its pa?4 ,!re are _m ways 9 :i* a wea!r prophecy may g wrong2 & !n we blame ! wea!r man4 ,we are likely to rememb] ! times t 8 prophecy is mi/ak5 & to =get ! _m1 _m times :5 x is "r4 ,illu/ration3 ,,fig4 #aef4 ,an an]oid b>omet] is m conv5i5t ?an "o made ) m]cury4 ,! walls are =c$ 9 or spr+ back out accord+ to ! pressure ( ! air4 ,?is movem5t ( ! walls =ces ! h& ar\nd4 ,,h[ ,,sn[ ,,is ,,=m$4 ,! diff]5ce betwe5 ! ways 9 :i* sn[ & ra9 are =m$ is v slight4 ,9 bo? cases wat] evaporates & its vapor m+les ) ! w>m air4 ,! w>m air rises & exp&s4 ,x cools z x exp&s1 & :5 x gets cool en\gh ! wat] vapor beg9s to cond5se4 ,b if ! air z x exp&s becomes v cold1 s cold t ! droplets ( wat] freeze z !y =m & ga!r toge!r to make delicate cry/als ( ice1 sn[ is =m$4 ,! ice cry/als f\nd 9 sn[ are always six-sid$ or six-po9t$1 because1 probably1 ! wat] or ice molecules pull f six directions & !re=e ga!r ea* o!r toge!r along ! six l9es ( ?is pull4 ,at any rate1 ! t9y cry/als ( froz5 wat] are =m$ & come float+ d[n to ! gr\nd2 & we call !m sn[flakes4 ,aft] ! sn[ melts x goes ?r\gh ! same cycle z ! ra91 mo/ ( x f9ally gett+ back to ! ocean ?r\gh riv]s1 & !re1 9 "t1 be+ evaporat$ once m4 ,illu/ration3 ,,fig4 #aeg4 ,diff]5t =ms ( sn[flakes4 ,ea* sn[flake is a collection ( small ice cry/als4 ,hail is ra9 t happ5s to be caught 9 a p[]ful curr5t ( ris+ air z x =ms1 & is c>ri$ up s high t x freezes 9 ! cold1 exp&+ air into little balls ( ice1 or hail /ones1 :i* fall to ! gr\nd be=e !y h "t to melt4 ,,:y ,,"o ,,side ,,( ,a ,,m\nta9 ,,range ,,usually ,,has ,,ra9fall4 ,:5 air t is mov+ along rea*es a m\nta9 range1 x ei!r w\ld h to /op1 or rise & g ov] ! m\nta94 ,! pressure ( ! air beh9d x1 mov+ 9 ! same direction1 keeps x f /opp+1 & s x has to g up ! slopes & ov] ! range4 ,b z x goes up1 !re is less air above x to pu% d[n on x2 s x exp&s4 ,?is makes x cool1 & ! wat] vapor 9 x beg9s to cond5se & =m sn[ or ra94 ,!re=e ! side ( m\nta9 ranges aga9/ :i* ! w9d usually bl[s1 almo/ always has pl5ty ( ra9fall4 ,x is diff]5t on ! f>!r side ( ! m\nta9 range4 ,= "h ! air is s9k+4 ,z x s9ks x is be+ compress$4 ,& z x is compress$ x is heat$4 ,if y hold y\r f+] ov] ! m\? ( a bicycle pump & compress ! air 9 ! pump by pu%+ d[n on ! h&le1 y w f9d t ! pump is decid$ly w>m$4 ,:5 ! air1 s9k+ d[n on ! f>!r side ( ! m\nta9 range1 is heat$1 ! wat] vapor 9 x is n at all likely to cond5se4 ,!re=e ra9 seldom falls on ! side ( ! m\nta9s :i* is turn$ away f ! prevail+ w9ds4 ,,h[ ,,dew ,,& ,,fro/ ,,are ,,=m$4 ,! heat ( ! e>? radiates out into ! air & on out into space4 ,at night1 :5 ! e>? loses its heat ?is way & does n receive heat f ! sun1 x becomes cool]4 ,:5 ! air1 c>ry+ its wat] vapor1 t\*es ! cool leaves & fl[]s1 ! wat] vapor is cond5s$ by ! coolness & =ms drops ( dew ^u !m4 ,or1 if ! night is cold]1 ! droplets freeze z !y =m1 & 9 ! morn+ we see ! grass & %rubs all cov]$ ) fro/4 ,,! ,,cause ,,( ,,fogs4 ,:5 w>m air is cool$ :ile x is d[n ar\nd u1 ! wat] vapor 9 x cond5ses into myriads ( droplets t float 9 ! air & make x foggy4 ,! air may be cool$ by bl[+ 9 f ! w>m lake or ocean 9 ! e>ly morn+1 = at night ! l& cools m rapidly ?an ! wat] does4 ,?is acc\nts = ! e>ly morn+ fogs 9 _m cities t are on ! coa/s4 ,likewise :5 ! w9d has be5 bl[+ ov] a w>m ocean curr5t1 ! surface ( ! w>m wat] evaporates & fills ! air ) wat] vapor4 ,!n :5 ?is air passes ov] a cold curr5t1 ! cold curr5t cools ! air s mu* t ! moi/ure 9 x cond5ses & =ms fog4 ,t is :y !re are fog banks1 dang]\s to navigation1 9 p>ts ( ! ocean1 p>ticul>ly (f ,labrador4 ,,:y ,,y ,,c ,,see ,,y\r ,,brea? ,,on ,,cold ,,days4 ,y really make a little fog :5 y brea! on a cold morn+4 ,! air 9 y\r lungs is w>m4 ,! moi/ure 9 ! lungs evaporates into ?is w>m air1 & y brea! x out4 ,if ! outside air is cold1 y\r brea? is cool$2 s "s ( ! wat] vapor 9 x cond5ses into v small droplets1 & y see y\r brea?4 ,"h are two exp]im5ts 9 cond5s+ wat] vapor by cool+ ! air ) :i* x is mix$4 ,bo? "w be/ if ! wea!r is w>m or ! air damp4 ,,exp]im5t #hh4 ,put ! bell j> on ! plate ( ! air pump & beg9 to pump ! air out ( x4 ,wat* ! air 9 ! j>4 ,if ! day is w>m or damp1 a slight mi/ w =m4 ,z "p ( ! air is pump$ out1 ! re/ exp&s & cools1 z w>m air does :5 x rises & is no long] press$ on s h>d by ! air above x4 ,& z 9 ! case ( ! ris+ w>m air1 ! wat] vapor cond5ses :5 x cools1 & =ms ! mi/ t y see4 ,?is mi/1 l all cl\ds & fog1 consi/s ( ?\s&s ( extremely small droplets4 ,,exp]im5t #hi4 ,hold a sauc] ( ice j bel[ y\r m\?4 ,op5 y\r m\? wide & brea! g5tly ov] ! ice4 ,c y see y\r brea?8 ,n[ put ! ice into half a glass ( wat] & cov] ! glass4 ,be sure ! outside ( ! glass is ?or\ghly dry4 ,set x aside & look at x aga9 9 a few m9utes4 ,:at caus$ ! mi/ :5 y brea!d across ! ice8 ,:]e did ! wat] on ! outside ( ! glass ( ice wat] come f8 ,:at made x cond5se8 ,illu/ration3 ,,fig4 #aeh4 ,if y bl[ g5tly ov] ice1 y c see y\r brea?4 ,,application #ff4 ,expla9 :y cl\ds are =m$ high 9 ! atmosph]e2 :y we h dew at night in/ead ( 9 ! daytime2 :y clo!s dry m quickly 9 a breeze ?an 9 /ill air2 :y clo!s dry m quickly on a sunny day ?an on a foggy "o4 ,illu/ration3 ,,fig4 #aei4 ,! glass does n leak2 ! moi/ure on x comes f ! air4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #daa4 ,a gas-fill$ electric lamp gets hott] ?an a vacuum lamp4 #dab4 ,y c remove a /amp f an envelope by soak+ x 9 wat]4 #dac4 ,we see our brea? on cold days & n on w>m days4 #dad4 ,! electric arc is exce$+ly hot4 #dae4 ,rock c&y is made by hang+ a /r+ 9 a /rong syrup left op5 to ! air4 #daf4 ,di%es 9 :i* c&y has be5 made %\ld be put to soak4 #dag4 ,moi/ure ga!rs on eyeglasses :5 ! we>] comes f a cold room into a w>m "o4 #dah4 ,spr9kl+ ! /reet on a hot day makes ! air cool4 #dai4 ,y _c see ?+s 9 a d>k room4 #dbj4 ,:]e air is ris+ !re is likely to be ra94 ,,section #de4 ,s(t5+ due to oil or wat]4 ,:y does fog dead5 a t5nis racket8 ,h[ does cold cream keep y\r face f becom+ *app$8 ,let u n[ imag9e t animal & plant sub/ances h sudd5ly lo/ _! ability to be s(t5$ by oil or wat]4 ,all liv+ ?+s soon feel v uncom=table4 ,y\r face & h&s /+ & crack2 ! sk9 all ov] y\r body becomes h>% & dry2 y\r m\? feels p>*$4 ,! %oes y are we>+ feel z if !y _h be5 dri$ ov] a radiator aft] be+ v wet1 only !y are /ill h>d] & m uncom=table4 ,a man driv+ a horse feels ! l9es /iff5+ 9 8 h&s2 & ! h>ness soon becomes s dry & brittle t x cracks & p]haps breaks if ! horse /ops sudd5ly4 ,! leaves on ! trees beg9 to rattle & break into pieces z ! w9d bl[s aga9/ !m4 ,al?\gh !y keep _! gre5ness1 !y act l ! drie/ leaves ( autumn4 ,i d\bt :e!r y or any "o c /ay alive long en\gh to notice su* effects4 ,= ! muscles ( y\r body1 includ+ ^? t make y brea! & make y\r he>t beat1 probably become s h>% & /iff t !y entirely fail to "w1 & y drop dead among ?\s&s ( o!r /iff1 h>%-sk9n$ animals & p4 ,s x is well t 9 ! real _w oil & wat] s(t5 practically all plant & animal tissues4 ,( c\rse1 9 liv+ plants & animals ! oil & wat] come l>gely f )9 !mselves4 ,y\r sk9 is kept moi/ & slightly oily all ! "t by little gl&s )9 x1 "s ( :i*1 call$ sweat gl&s1 secrete p]spiration & o!rs ( :i* secrete oil4 ,b sometimes ! oil is wa%$ (f ! surface ( y\r h&s1 z :5 y wa% an article 9 gasol9e or /rong soap4 ,!n y feel t y\r sk9 is dry & h>%4 ,& :5 y want to s(t5 x aga9 y rub into x oily sub/ances1 l cold cream or vasel9e4 ,9 ! same way if h>ness or %oes get wet & !n are dri$ out1 !y c be made prop]ly flexible by oil+4 ,y c\ld wet !m1 ( c\rse1 & ?is w\ld s(t5 !m z long z !y /ay$ wet4 ,b wat] evaporates r quickly2 s :5 y want a ?+ to /ay s(t1 y usually apply "s k9d ( oil or grease4 ,j z diffusion & ! =m+ ( solutions are increas$ by heat1 ?is s(t5+ by oil & wat] works bett] if ! oil or wat] is w>m4 ,t is :y y soak y\r h&s 9 w>m wat] be=e manicur+ y\r nails4 ,,application #fg4 ,expla9 :y wom5 damp5 clo!s be=e iron+ !m2 :y crack]s are put up 9 wat]pro( c>tons2 :y an oil %oe poli% is bett] ?an "o conta9+ wat]4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dba4 ,y c %ort5 y\r f+] nails by fil+ !m4 #dbb4 ,y c d x m quickly aft] wa%+ !m ?an be=e4 #dbc4 ,aft] a fla%light picture is tak51 ! smoke soon rea*es all p>ts ( ! room4 #dbd4 ,a jewel] we>s a convex l5s on 8 eye :5 he works ) small objects4 #dbe4 ,%oemak]s soak ! lea!r be=e half-sol+ %oes4 #dbf4 ,lightn+ (t5 sets fire to h\ses or trees t x /rikes4 #dbg4 ,! directions on _m bottles ( m$ic9e & ( prep>ations = h\sehold use say1 ,%ake well be=e us+4 #dbh4 ,if y set a cold tumbl] inside ( "o t has j be5 wa%$ 9 hot wat]1 ! out] "o w crack 9 a few m9utes4 #dbi4 ,a dry clo? hung out at night becomes wet1 :ile a wet clo? hung out on a cle> day dries4 #dcj4 ,putt+ cold cream or tall[ ar\nd ! roots ( y\r f+] nails w help to prev5t hangnails4 ,,*apt] ,,t5 ,,*emical ,,*ange ,,& ,,en]gy ,,section #df4 ,:at ?+s are made (3 ,elem5ts4 ,:at is wat] made (8 ,:at is iron made (8 ,is ev]y?+ made out ( du/8 ,"o ( ! mo/ natural que/ions 9 ! _w is1 ,:at is ?is made (8 ,if we are talk+ ab\t a piece ( bread1 ! answ] is1 ( c\rse1 fl\r1 wat]1 milk1 %ort5+1 sug>1 salt1 & yea/4 ,b :at is ea* ( ^! made (8 ,fl\r is made ( :eat1 & ! :eat is made ( mat]ials t ! plant gets f ! e>?1 wat]1 & air4 ,!n :at are ! e>?1 wat]1 & air made (8 ,a *emi/ is a p]son :o c answ] ^! que/ions & :o c tell :at almo/ ev]y?+ is made (4 ,& a /range ?+ t *emi/s h f\nd out is ?is3 ,ev]y?+ 9 ! _w is made out ( "o or m ( ab\t eighty-five simple sub/ances call$ elem5ts4 ,,:at ,,an ,,elem5t ,,is4 ,an elem5t is a sub/ance t is n made ( any?+ else b itself4 ,gold is "o ( ! eighty-five elem5ts2 !re are no o!r sub/ances kn[n to man t y c put toge!r to make gold4 ,x is made ( gold & t is all4 ,!re is a !ory t maybe all ! elem5ts are made ( electrons 9 diff]5t arrangem5ts1 or ( electrons & "o o!r ?+2 b we d n "k t1 x is only a !ory4 ,c>bon is ano!r elem5t2 pure *>coal is c>bon4 ,! "p ( ! air t we use :5 we brea! or :5 we burn ?+s is call$ oxyg54 ,oxyg5 is an elem5t2 x is n made ( any?+ b itself4 ,!re is ano!r gas :i* is (t5 us$ to fill balloons t are to g v high2 x is ! lighte/ 9 ! _w & is call$ hydrog54 ,hydrog5 is an elem5t4 ,= a long "t p ?\ght t wat] 0 an elem5t4 ,wat] c]ta9ly looks & seems z if x 7 made only ( itself4 ,yet dur+ ! ?\s&s ( ye>s t p believ$ wat] 0 an elem5t1 !y 7 daily putt+ two elem5ts toge!r & mak+ wat] out ( !m4 ,:5 y put a kettle1 or any?+ cold1 ov] a fire1 t9y drops ( wat] always =m on x4 ,^! are n drops ( wat] t 7 dissolv$ 9 ! air1 & t cond5se on ! sides ( ! cold kettle2 if !y 71 !y w\ld ga!r on ! kettle bett] 9 ! op5 air ?an ov] ! hot fire4 ,really !re is "s ( t v light gas1 hydrog51 9 ! wood or coal or gas t y use1 & ?is hydrog5 jo9s ! oxyg5 9 ! air to make wat] :5ev] we burn ord9>y fuel4 ,b ! be/ way to prove t wat] is made ( two gases is to take ! wat] ap>t & get ! gases f x4 ,"h are ! directions = do+ ?is3 ,,exp]im5t #ij4 ,a regul> b\ght electrolysis app>atus may be us$1 or y c make a simple "o z foll[s3 ,use a tumbl] & two te/ tubes4 ,if ! te/ tubes are r small 7#c_/h'' ,x #c''7 !y w fill m quickly4 ,dissolve a little lye 7ab\t #a_/h teaspoonful7 9 half a p9t ( wat] to make ! wat] conduct electricity easily1 or y may use sulfuric acid 9 place ( lye4 ,p\r half ( ?is solution into ! tumbl]4 ,p\r z mu* m z possible into ! te/ tubes1 fill+ bo? tubes brim full4 ,cov] ! m\? ( ea* te/ tube ) a small squ>e ( dry pap] or c>dbo>d1 & turn x upside d[n1 l[]+ x into ! tumbl]4 ,! electrodes are two #c_/d'' pieces ( plat9um wire 7#cj71 :i* are sold]$ to two pieces ( insulat$ copp] wire1 ea* ab\t #b feet long4#h ,! o!r ends ( ! copp] wire are b>e4 ,fa/5 ! b>e end ( "o copp] wire to "o nail ( ! nail plug if y h direct curr5t 7d4 c47 9 ! laboratory1 & fa/5 ! b>e end ( ! o!r wire to ! o!r nail2 !n turn on ! electricity4 ,if y d n h direct curr5t 9 ! laboratory1 atta* ! copp] wires to ! two poles ( a batt]y in/ead4 ,footnote #h3 ,if ! copp] wire is drawn ?r\gh a piece ( #a_/d-;in* s(t glass tub+ s t only ! plat9um wire projects f ! end ( ! tube1 & ! tube is !n seal$ ar\nd ! plat9um by hold+ x 9 a ,buns5 burn] a few m9utes1 y\r electrodes w be m p]man5t & m satisfactory4 ,! pieces ( glass tub+ %\ld be ab\t #f in*es long 7see ,fig4 #afj74 ,b5d ! plat9um electrodes up s t !y w /ick up into ! te/ tubes f bel[4 ,bubbles %\ld imm$iately beg9 to ga!r on ! plat9um wire & to rise 9 ! te/ tubes4 ,z ! te/ tubes fill ) gas1 ! wat] is =c$ out2 s y c tell h[ mu* gas has collect$ at any "t by see+ h[ mu* wat] is left 9 ea* tube4 ,"o tube %\ld fill ) gas twice z fa/ z ! o!r4 ,! gas 9 ?is tube is hydrog52 !re is twice z mu* hydrog5 z !re is oxyg5 9 wat]4 ,! tube t fills m sl[ly conta9s oxyg54 ,:5 ! fa/]-fill+ tube is full ( hydrog5--t is1 :5 all ( ! wat] has be5 =c$ out ( x--take ! electrode out & let x hang loose 9 ! glass4 ,put a piece ( c>dbo>d ab\t #a in* squ>e ov] ! m\? ( ! te/ tube2 take ! te/ tube out ( ! wat] & turn x "r side up1 keep+ x cov]$ ) ! c>dbo>d4 ,light a mat*1 remove ! c>dbo>d cov]1 & hold ! mat* ov] ! op5 te/ tube4 ,does ! hydrog5 9 x burn8 ,:5 ! tube conta9+ ! oxyg5 is full1 take x out1 cov]$1 j z y did ! hydrog5 te/ tube4 ,b 9 ?is case make ! end ( a /ick ( *>coal gl[1 remove ! c>dbo>d f ! tube1 & !n plunge ! gl[+ *>coal into ! te/ tube full ( oxyg54 ,illu/ration3 ,,fig4 #afj4 ,! electrodes are made ( loops ( plat9um wire seal$ 9 glass tubes4 ,only oxyg5 w make *>coal bur/ into flame l ?is4 ,:5 p f\nd t !y c\ld take wat] ap>t 9 ?is way & turn x into hydrog5 & oxyg51 & :5 !y f\nd t :5ev] !y comb9$ hydrog5 ) oxyg5 !y got wat]1 !y knew1 ( c\rse1 t wat] 0 n an elem5t4 ,maybe "s day !y w f9d t "s ( ! eighty-five or s sub/ances t we n[ consid] elem5ts c really be divid$ into two or m elem5ts2 b s f> ! elem5ts we "k %[ no signs ( be+ made ( any?+ except !mselves4 ,! la/ section ( ?is book w expla9 some?+ ab\t ! way ! *emi/ goes to "w to f9d out :at elem5ts are hidd5 9 comp\nds4 ,illu/ration3 ,,fig4 #afa4 ,wat] c be sep>at$ into two gases by a curr5t ( electricity4 ,,! ,,quick ,,way ,,*emi/s ,,write ,,ab\t ,,elem5ts4 ,s9ce ev]y?+ 9 ! _w is made ( a comb9ation or a mixture ( elem5ts1 *emi/s h f\nd x v conv5i5t to make abbreviations = ! names ( ! elem5ts s t !y c quickly write :at a ?+ is made (4 ,!y indicate hydrog5 by ! lett] ,h4 ,o always means oxyg5 to ! *emi/2 ,c means c>bon2 & ,cl means *lor9e1 ! poison gas s mu* us$ 9 ! ,_w ,w>4 ,! abbreviation /&s = ! ,lat9 "n ( ! elem5t in/ead ( = ! ,engli% "n1 b !y are (t5 almo/ alike4 ,! ,lat9 "n = ! metal sodium1 h[ev]1 is natrum1 & *emi/s always write ,na :5 !y mean sodium2 ?is is =tunate1 because ,s already /&s = ! elem5t sulfur4 ,fe means iron 7,lat91 f]rum74 ,b ,i /&s = ! elem5t iod9e4 7,! iod9e y use :5 y get scrat*$ is ! elem5t iod9e dissolv$ 9 alcohol47 ,x is n necess>y = y to rememb] ! *emical symbols unless y mean to become a *emi/ or unless y read a good deal ab\t *emi/ry4 ,b almo/ e "o kn[s at lea/ t ,h means hydrog51 ,o means oxyg51 & ,c means c>bon4 ,:5 a *emi/ wants to %[ t wat] is made ( hydrog5 two p>ts & oxyg5 "o "p1 he writes x v quickly l ?is3 ,h#b,o 7pron\nc$ ,h two ,o74 ,h#b,o means to a *emi/ j z mu* z w-a-t-e-r means to y2 & x means ev5 m1 because x tells t wat] is made ( two p>ts hydrog5 & "o "p oxyg54 ,if a *emi/ want$ to write1 ,y c take wat] ap>t & x w give y two p>ts ( hydrog5 & also "o "p ( oxyg51 ?is is :at he w\ld put d[n3 ,h#b,o - #b;,h,o4 ,if he want$ to %[ t y c\ld comb9e two p>ts ( hydrog5 & "o "p ( oxyg5 to =m wat]1 he w\ld write x quickly l ?is3 #b;,h,o - ,h#b,o4 ,^! are call$ *emical equations4 ,y d n ne$ to rememb] !m2 !y are put "h m]ely s t y w "k :at !y look l4 ,"s ( !m are mu* long] & m complicat$1 l ?is3 ,,hc#b;,h#c,o#b,na,h,c,o#c - ,h#b,o,,co#b,na,c#b;,h#c,o#b4 ,?is is ! *emi/'s way ( say+1 ,v9eg> is made ( "o "p ( hydrog5 gas t w come (f easily & t gives x its s\r ta/e1 two p>ts ( c>bon1 ?ree p>ts ( hydrog5 t does n come (f s easily1 & two p>ts ( oxyg54 ,:5 y put ?is ) bak+ soda1 :i* is made ( "o "p ( ! metal sodium1 "o "p ( hydrog51 "o "p ( c>bon1 & ?ree p>ts ( oxyg51 y get wat] & c>bon dioxid gas & a k9d ( salt call$ sodium acetate4 ,or1 m briefly1 ,if y put bak+ soda ) v9eg>1 y get wat]1 a gas call$ c>bon dioxid1 & a salt4 ,y c see h[ mu* %ort] ! *emi/'s way ( writ+ x is4 ,,"s ,,elem5ts ,,y ,,already ,,"k4 ,"h is a li/ ( "s elem5ts t y are already pretty well acqua9t$ )4 ,! abbreviation is put aft] ! "n = ea*4 ,?is li/ is only = ref]5ce & ne$ n be le>n$4 ,alum9um 7,al7 ,c>bon 7,c7 ,*>coal1 diamonds1 graphite 7! lead 9 a p5cil is graphite71 h>d coal1 & soot are all made ( c>bon4 ,*lor9e 7,cl7 ,a poison gas t 0 us$ 9 ! w>4 ,copp] 7,cu7 ,gold 7,au7 ,hydrog5 7,h7 ,! lighte/ gas 9 ! _w2 y got x f wat] 9 ! la/ exp]im5t & w get x f an acid 9 ! next4 ,iod9e 7,i7 ,x is a solid2 :at y use is iod9e dissolv$ 9 alcohol4 ,iron 7,fe7 ,lead 7,pb7 ,m]cury 7,hg7 ,?is is ano!r "n = quicksilv]4 ,nickel 7,ni7 ,nitrog5 7,n7 ,ab\t f\r fif?s ( ! air is pure nitrog54 ,oxyg5 7,o7 ,?is is ! "p ( ! air we use 9 brea?+4 ,y got "s out ( wat]1 & y w h x to deal ) 9 ano!r exp]im5t4 ,phosphorus 7,p7 ,phosphorus makes mat*es gl[ 9 ! d>k1 & x makes !m /rike easily4 ,plat9um 7,pt7 ,radium 7,ra7 ,silv] 7,ag7 ,sodium 7,na7 ,y are n acqua9t$ ) sodium by itself1 b :5 x is comb9$ ) ! poison gas1 *lor9e1 x makes ord9>y table salt4 ,sulfur 7,s7 ,t9 7,sn7 ,z9c 7,zn7 ,= ! re/ ( ! elem5ts y c ref] to any textbook on *emi/ry4 ,,h[ ,,elem5ts ,,hide ,,9 ,,comp\nds4 ,"o /range ?+ ab\t an elem5t is t x c hide s completely1 by comb9+ ) ano!r elem5t1 t y w\ld nev] "k x 0 pres5t unless y took ! comb9ation ap>t4 ,take ! black elem5t c>bon1 = in/ance4 ,sug> is made entirely ( c>bon & wat]4 ,y c tell ?is by mak+ sug> v hot4 ,:5 x is hot en\gh1 x turns black2 ! wat] "p is driv5 (f & ! c>bon is left beh9d4 ,yet to look at dry1 :ite sug>1 or to ta/e its sweetness1 "o w\ld nev] suspect t x 0 made ( pure black1 ta/eless c>bon & colorless1 ta/eless wat]4 ,mix+ c>bon & wat] w\ld nev] give y sug>4 ,b comb9+ !m 9 ! "r proportions into a *emical comp\nd does produce sug>4 ,n only is c>bon conceal$ 9 sug>1 b x is pres5t 9 all plant & animal matt]4 ,t is :y burn+ almo/ any k9d ( food makes x black4 ,y drive (f mo/ ( ! o!r elem5ts & sep>ate ! food into its p>ts by gett+ x too hot2 ! wat] evaporates & s does ! nitrog52 :at is left is ma9ly black c>bon4 ,,mak+ ,,hydrog5 ,,come ,,out ,,( ,,hid+4 ,! light gas1 hydrog51 conceals itself z p]fectly z c>bon does by comb9+ ) o!r elem5ts4 ,x is hid+ 9 ev]y?+ t is s\r & 9 _m ?+s t are n s\r4 ,& y c get x out ( s\r ?+s ) metals4 ,9 "s cases x is h>d] to sep>ate ?an 9 o!rs2 & "s metals sep>ate x bett] ?an o!rs d4 ,b "o s\r comp\nd t y c easily get ! hydrog5 out ( is hydro*loric acid 7,h,cl71 :i* is hydrog5 comb9$ ) ! poison gas1 *lor9e4 ,"o ( ! be/ metals to get ! hydrog5 out ) is z9c4 ,"h are ! directions = do+ x & incid5tally = mak+ a toy balloon3 ,,exp]im5t #ia4 ,d ?is exp]im5t on ! side ( ! laboratory f>!/ f any flames or fire4 ,d n let any flame come ne> ! flask 9 :i* y are mak+ hydrog54 ,9 ! bottom ( a flask put two or ?ree wads ( z9c %av+s1 ea* ab\t ! size ( y\r ?umb4 ,fit a "o-hole rubb] /opp] to ! flask4 ,take ! /opp] out & put a piece ( glass tub+ ab\t #e in*es long ?r\gh ! hole ( ! /opp]1 lett+ half an in* or s /ick d[n into ! flask :5 ! /opp] is 9 place 7,fig4 #afb74 ,) a rubb] b& fa/5 ! m\? ( a rubb] balloon ov] ! end ( ! glass tube t w be upp]mo/4 ,fill ! balloon by bl[+ ?r\gh ! glass tube to see if all connections are tight1 & to see h[ f> x may be exp&$ )\t dang] ( break+4 ,y c tell :5 ! balloon has ab\t all x w hold1 by press+ g5tly ) y\r f+]s4 ,if ! rubb] feels tight1 d n bl[ any m4 ,let ! air out ( ! balloon aga94 ,n[ get "s hydro*loric acid 7,h,cl7 dilut$ ) ?ree p>ts ( wat]4 ,f9d ! bottle m>k$ ,h,cl1 dilute #a-c1 9 :i* ! acid is already dilut$4 ,be=e y op5 ! bottle1 get "s solution ( soda1 & keep x ne> y2 if 9 ?is exp]im5t or any o!r y spatt] acid on y\r h&s or face or clo!s1 wa% x (f imm$iately ) soda solution4 ,rememb] ?is4 ,ammonia w d z well z ! soda solution to wa% (f ! acid1 b be c>eful n to get x into y\r eyes4 ,p\r ! hydro*loric acid 7,h,cl7 on ! z9c %av+s 9 ! bottom ( ! flask1 until ! acid /&s ab\t an in* deep4 ,!n quickly put ! rubb] /opp] ) its atta*m5ts into ! flask1 s t ! gas t bubbles up w bl[ up ! balloon4 ,if ! bubbles d n =m rapidly1 ask ! tea*] to p\r a little /rong hydro*loric acid into ! flask2 b ?is w probably n be necess>y4 ,let ! balloon keep fill+ until x is z l>ge z y blew x4 ,b if ! bubbles /op com+ be=e x gets z l>ge z t1 close ! neck ( ! balloon by p9*+ x tightly1 & take ! /opp] out4 ,let "s "o add m z9c %av+s & m acid to ! flask2 put ! /opp] back 91 & /op p9*+ ! neck ( ! balloon4 ,9 ?is & all o!r exp]im5ts :5 y use /rong acids1 p\r ! us$ acids into ! crock]y j> t is provid$ = su* wa/es4 ,d n p\r !m into ! s9k1 z acids ru9 s9k dra9pipes4 ,:5 ! balloon is full1 close ! neck by slipp+ ! rubb] b& up f ! "p ( ! neck t is ov] ! glass tube on to ! upp] "p ( ! neck4 ,pull ! balloon (f ! glass tube & p9* ! neck firmly %ut4 ,take ! /opp] out & r9se ! flask sev]al times ) runn+ wat]4 ,any z9c t is left %\ld be r9s$ ?or\ghly1 dri$1 & set aside s t x may be us$ aga94 ,n[ tie "o end ( a long ?read firmly ar\nd ! m\? ( ! balloon & let ! balloon g4 ,does x rise8 ,if x does n1 ! reason is t y did n get x full en\gh4 ,9 t case make m hydrog5 & fill x full]1 z expla9$ above4 ,illu/ration3 ,,fig4 #afb4 ,fill+ a balloon ) hydrog54 ,illu/ration3 ,,fig4 #afc4 ,add+ m acid )\t los+ ! gas4 ,"h is ano!r exp]im5t ) hydrog53 ,,exp]im5t #ib4 ,put a wad ( z9c %av+s1 ab\t ! size ( ! end ( y\r little f+]1 into ! bottom ( a te/ tube4 ,cov] x ) hydro*loric acid 7,h,cl7 dilut$ "o to ?ree1 z 9 ! prec$+ exp]im5t4 ,aft] ! bubbles h be5 ris+ = a c\ple ( m9utes1 take ! te/ tube to ! side ( ! laboratory :]e ! burn]s are1 & hold a light$ mat* at its m\?4 ,w hydrog5 burn8 ,rememb] t ! hydrog5 :i* ! z9c is driv+ out ( ! acid is exactly ! same z ! hydrog5 y drove out ( wat] ) an electric curr5t4 ,!re is a metal call$ sodium 7,na7 & ano!r call$ potassium 7,k7 :i* are z s(t z /iff putty & z %9y z silv]2 if y put a t9y piece ( sodium 7,na7 or potassium 7,k7 on wat]1 x w drive ! hydrog5 out ( ! wat] j z z9c drove x out ( ! acid4 ,! action is s swift & viol5t & releases s mu* heat t ! hydrog5 :i* is set free cat*es fire4 ,?is makes x look z if ! metal 7 burn+ z x sputt]s ar\nd on top ( ! wat]4 ,!re is s mu* sputt]+ t ! exp]im5t is dang]\s2 p h be5 bl9d$ by ! hot alkal9e wat] spatt]+ into _! eyes4 ,s y _c try ?is until sometime :5 y take a regul> c\rse 9 *emi/ry4 ,illu/ration3 ,,fig4 #afd4 ,try+ to see if hydrog5 w burn4 ,,gett+ ,,oxyg51 ,a ,,gas1 ,,f ,,two ,,solids4 ,oxyg5 7,o7 c hide j z successfully z hydrog54 ,practically all elem5ts c d ! same by comb9+ ) o!rs4 ,"h is an exp]im5t 9 :i* y c get ! gas1 oxyg51 out ( a c\ple ( solids4 ,if y w5t to ! moon or "s o!r place :]e !re is no air1 y c\ld c>ry oxyg5 v conv5i5tly lock$ up 9 ^! solid sub/ances4 ,oxyg51 y rememb]1 is ! "p ( ! air t keeps u alive :5 we brea! x4 ,,exp]im5t #ic4 ,9 a te/ tube mix ab\t "o half teaspoonful ea* ( :ite potassium *lorate cry/als & black gra9s ( manganese dioxid4 ,put a piece ( glass tub+ ?r\gh a cork s t ! tub+ w /ick d[n a little way into ! te/ tube4 ,d n put ! glass tub+ ?r\gh ! cork :ile ! cork is 9 ! te/ tube3 ins]t ! glass tub+ fir/1 !n put ! cork into ! te/ tube4 ,put "o end ( a #b-;foot piece ( rubb] tub+ ov] ! glass tube & put ! o!r end into a pan ( wat]4 ,fill a flask or bottle to ! brim ) wat]1 lett+ x ov]fl[ a little2 hold a piece ( c>dbo>d firmly ov] ! m\? ( ! bottle2 turn ! bottle upside d[n quickly1 putt+ ! m\? ( x "u wat] 9 ! pan2 take ! c>dbo>d away4 ,! wat] %\ld all /ay 9 ! bottle4 ,n[ %ove ! rubb] tube into ! neck ( ! bottle until x /icks up an in* or two4 ,dur+ ?is exp]im5t1 be c>eful n to let ! neck ( ! bottle or flask p9* ! rubb] tub+2 small pieces ( wood or glass tub+ laid beside ! rubb] tub+ :]e x goes "u ! run ( ! neck w prev5t ?is4 ,hold1 ! te/ tube1 tightly cork$1 ov] ! flame ( a burn]1 keep+ ! tube at a slant & mov+ x slightly back & =? s t all ! mat]ial 9 x w be ?or\ghly heat$4 ,if y /op heat+ ! te/ tube ev5 = a c\ple ( seconds1 take ! cork out2 if y d n remove ! cork1 ! cool+ gas 9 ! te/ tube w %r9k & all[ ! wat] f ! pan to be =c$ ?r\gh ! rubb] tube into ! te/ tube1 break+ x into pieces4 ,:5 en\gh gas has bubbl$ up into ! bottle to =ce all ! wat] out1 & :5 bubbles beg9 to come up outside ! bottle1 uncork ! te/ tube & lay x aside :]e x w n burn any?+2 !n slide ! c>dbo>d "u ! m\? ( ! bottle & turn x "r side up2 leave ! c>dbo>d on ! bottle4 ,light a piece ( *>coal1 or let a spl9t] ( wood burn a few m9utes & !n bl[ x out s t a gl[+ coal w be left on ! end ( x4 ,lift ! c>dbo>d (f ! bottle & plunge ! gl[+ /ick into x = a c\ple ( seconds4 ,cov] ! bottle aft] tak+ out ! /ick1 & repeat1 us+ a light$ mat* or a burn+ piece ( wood in/ead ( ! gl[+ /ick4 ,if y dip a piece ( iron picture wire 9 sulfur & light x1 & !n plunge x into ! bottle1 y w see iron burn4 ,illu/ration3 ,,fig4 #afe4 ,fill+ a bottle ) oxyg54 ,illu/ration3 ,,fig4 #aff4 ,! iron really burns 9 ! j> ( oxyg54 ,bo? manganese dioxid & potassium *lorate h a great deal ( oxyg5 b\nd up 9 !m4 ,:5 !y jo9 toge!r1 z !y d :5 y heat !m1 !y _c hold s mu* oxyg51 & x escapes z a gas4 ,9 ! exp]im5t1 ! escap+ oxyg5 pass$ ?r\gh ! tube1 fill$ ! bottle1 & =c$ ! wat] out4 ,,:at ,,burn+ ,,is4 ,:5 any?+ burns1 x is simply jo9+ oxyg54 ,:5 a ?+ burns 9 air1 x _c jo9 ! oxyg5 ( ! air v fa/1 = e qu>t ( oxyg5 9 ! air is dilut$ ) a gallon ( a gas call$ nitrog54 ,nitrog5 w n burn & x w n help any?+ else to burn4 ,b :5 y h pure oxyg51 z 9 ! bottle1 ! p>ticles ( wood or *>coal or picture wire c jo9 x easily2 s !re is a v bright blaze4 ,al?\gh free oxyg5 helps ?+s to burn s brilliantly1 a mat* appli$ to ! solids f :i* y got x w\ld g out4 ,& :ile hydrog5 burns v easily1 y _c burn wat] al?\gh x is two-?irds hydrog54 ,wat] is ,h#b,o1 y rememb]4 ,,:at ,,comp\nds ,,are4 ,:5 elem5ts are comb9$ ) o!r elem5ts1 ! new sub/ances t are =m$ are call$ comp\nds4 ,wat] 7,h#b,o7 is a comp\nd1 because x is made ( hydrog5 & oxyg5 comb9$4 ,:5 elem5ts unite to =m comp\nds1 !y lose _! orig9al qualities4 ,! oxyg5 9 wat] w n let ?+s burn 9 x2 ! hydrog5 9 wat] w n burn4 ,salt 7,na,cl7 is a comp\nd4 ,x is made ( ! s(t metal sodium 7,na71 :i* :5 plac$ on wat] sputt]s & drives hydrog5 out ( ! wat]1 & ! poison gas *lor9e 7,cl71 comb9$ ) ea* o!r4 ,& salt is nei!r dang]\s to put 9 wat] l sodium1 nor is x a gre5i% poison gas l *lor9e4 ,,mixtures4 ,b sometimes elem5ts c be mix$ )\t _! comb9+ to =m comp\nds1 9 su* a way t !y keep mo/ ( _! orig9al prop]ties4 ,air is a mixture4 ,x is made ( oxyg5 7,o7 & nitrog5 7,n74 ,if !y 7 comb9$1 in/ead ( mix$1 !y might =m laugh+ gas1--! gas d5ti/s use 9 putt+ p to sleep :5 !y pull tee?4 ,s x is well = u t air is only a mixture ( oxyg5 & nitrog51 & n a comp\nd4 ,y f\nd t ?+s burn$ brilliantly 9 oxyg54 ,well1 ?+s burn 9 air too1 because a fif? ( ! air is oxyg5 & ! oxyg5 ( ! air has all its orig9al prop]ties left4 ,?+s d n burn z brightly 9 air z !y d 9 pure oxyg5 = ! same reason t a teaspoonful ( sug> mix$ ) #d teaspoonfuls ( boil$ rice does n ta/e z sweet z pure sug>4 ,! sug> itself is z sweet1 b x is n z conc5trat$4 ,likewise ! oxyg5 9 ! air is z able to help ?+s burn z pure oxyg5 is2 b x is dilut$ ) f\r times its own volume ( nitrog54 ,a solution is a mixture1 too2 = al?\gh sub/ances disappe> :5 !y dissolve1 !y keep _! own prop]ties4 ,sug> is sweet :e!r x is dissolv$ or n4 ,salt dissolv$ 9 wat] makes br9e2 b ! wat] w act 9 ! way t x did be=e4 ,x w /ill help to make iron ru/2 & salt w be salty1 :e!r or n x is dissolv$ 9 wat]4 ,t is :y solutions are only mixtures & are n *emical comp\nds4 ,,ev]y?+ ,,9 ,,! ,,_w ,,is ,,made ,,( ,,atoms4 ,ev]y?+ 9 ! _w is ei!r an elem5t or a comp\nd or a mixture4 ,mo/ plant & animal matt] is made ( v complicat$ comp\nds1 or mixtures ( comp\nds4 ,all pure metals are elem5ts2 b metals1 :5 !y are melt$1 c be dissolv$ 9 ea* o!r to =m alloys1 :i* really are mixtures4 ,mo/ ( ! s-call$ gold & silv] & nickel articles are really made ( alloys2 t is1 ! gold1 silv]1 or nickel has "s o!r elem5ts dissolv$ 9 x to make x h>d]1 or to imp>t "s o!r quality4 ,bronze & brass are always alloys2 /eel is g5]ally an alloy made *iefly ( iron b ) o!r elem5ts su* z tung/51 ( :i* electric lamp filam5ts are made1 dissolv$ 9 x to make x h>d]4 ,an alloy is a special k9d ( solution n q l an ord9>y solution4 ,y rememb] t 9 ! op5+ *apt]s we (t5 spoke ( molecules1 ! t9y p>ticles ( matt] t are always mov+ rapidly back & =?4 ,well1 if y 7 to exam9e a molecule ( wat] ) ! microscope :i* we imag9$ c\ld %[ u molecules1 y w\ld f9d t ! molecule ( wat] 0 made ( ?ree /ill small] p>ticles1 call$ atoms4 ,two ( ^! w\ld be atoms ( hydrog5 & w\ld probably be especially small2 ! ?ird w\ld be l>g] & w\ld be an oxyg5 atom4 ,9 ! same way if y look$ at a molecule ( salt "u ?is imag9>y microscope1 y w\ld probably f9d x made ( two atoms1 "o ( sodium 7,na7 & "o ( *lor9e 7,cl71 held fa/ toge!r 9 "s way :i* we d n entirely und]/&4 ,! smalle/ p>ticle ( an elem5t is call$ an atom4 ,! smalle/ p>ticle ( a comp\nd is call$ a molecule4 ,molecules are usually made ( two or m atoms jo9$ toge!r4 ,,application #fh4 ,9 ! foll[+ li/ tell :i* ?+s are elem5ts1 :i* are comp\nds1 & :i* are mixtures1 rememb]+ t bo? solutions & alloys are mixtures3 ,air1 wat]1 salt1 gold1 hydrog51 milk1 oxyg51 radium1 nitrog51 sulfur1 bak+ soda1 sodium1 diamonds1 sweet5$ c(fee1 phosphorus1 hydro*loric acid1 brass4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dca4 ,al?\gh 9 mo/ electric lamps !re is a vacuum betwe5 ! gl[+ filam5ts & ! glass1 ! glass nev]!less becomes w>m4 #dcb4 ,clo!s left out on ! l9e ov]night usually become damp4 #dcc4 ,y c sep>ate wat] into hydrog5 & oxyg51 yet y _c sep>ate ! hydrog5 or ! oxyg5 into any o!r sub/ances4 #dcd4 ,wet pap] te>s easily4 #dce4 ,w9d[s are soil$ on ! outside mu* m quickly 9 ra9y wea!r ?an 9 cle> wea!r4 #dcf4 ,if y /ir iron & s& toge!r1 ! iron w ru/ z if alone4 #dcg4 ,ru/ is made ( iron & oxyg51 yet y _c sep>ate ! iron f ! oxyg5 ) a magnet4 #dch4 ,a read+ glass helps y to read f9e pr9t4 #dci4 ,/ret*+ ! /r+ ( a musical in/rum5t m tightly makes ! note high]4 #ddj4 ,mayonnaise dress+1 al?\gh x conta9s mu* oil1 c readily be wa%$ (f a plate ) cold wat]4 ,,section #dg4 ,burn+3 ,oxidation4 ,:at makes smoke8 ,:at makes fire burn8 ,:y does air keep u alive8 ,:y does an apple turn br[n aft] y peel x8 ,if oxyg5 %\ld sudd5ly lose its p[] ( comb9+ ) o!r ?+s to =m comp\nds1 e fire 9 ! _w w\ld g out at once4 ,y c\ld g on brea?+ at fir/1 b y\r brea?+ w\ld be useless4 ,y w\ld %iv]1 beg9 to /ruggle1 & dea? w\ld come1 all )9 a m9ute or two4 ,plants & trees w\ld die1 b !y w\ld rema9 /&+ until bl[n d[n by ! w9d4 ,ev5 ! fi% 9 ! wat] w\ld all die 9 a few m9utes1--m quickly ?an !y usually d :5 we take !m out ( ! wat]4 ,9 a v %ort "t ev]y?+ 9 ! _w w\ld be dead4 ,!n suppose t ?is condition la/$ = hundr$s & hundr$s ( ye>s1 ! oxyg5 rema9+ unable to comb9e ) o!r elem5ts4 ,dur+ all t "t no?+ w\ld decay4 ,! trees w\ld /ay z !y fell4 ,! corpses ( p w\ld dry & %rivel1 b !y w\ld lie :]e !y dropp$ z p]fectly pres]v$ z ! be/ ( mummies4 ,! dead fi% w\ld float ab\t 9 ! oceans & lakes4 ,?is is all because life is kept up by burn+4 ,& burn+ is simply ! comb9+ ( diff]5t ?+s ) oxyg54 ,if oxyg5 ceas$ to comb9e ) ! wood or gas or :atev] fuel y use1 t fuel c\ld n burn2 h[ c\ld x :5 burn+ means comb9+ ) oxyg58 ,! heat 9 y\r body & ! en]gy ) :i* y move come entirely f ! burn+ 7oxidation7 ( mat]ials 9 y\r body2 & t is :y y h to brea!2 y ne$ to get m & m oxyg5 into y\r body all ! "t to comb9e ) ! c>bon & hydrog5 9 ! cells ( :i* y\r body is made4 ,plants brea!1 too4 ,!y d n ne$ s mu* oxyg51 s9ce !y d n keep w>m & d n move ar\nd2 b ea* plant cell ne$s oxyg5 to live2 !re is burn+ 7oxidation7 go+ on 9 e liv+ cell4 ,fi%es brea! oxyg5 ?r\gh _! gills1 absorb+ ! oxyg5 t is dissolv$ 9 ! wat]4 ,!y d n take ! wat] ap>t to get "s ( ! comb9$ oxyg5 f x2 !re is always "s free oxyg5 dissolv$ 9 any wat] t is op5 to ! air4 ,x is cle> t fires w\ld all g out & ev]y?+ w\ld die if burn+ 7comb9+ ) oxyg57 /opp$4 ,! reason ?+s w\ld n decay is t decay usually is a sl[ k9d ( oxidation 7burn+74 ,:5 x is n ?is1 x is ! action ( bact]ia4 ,b bact]ia !mselves c\ld n live if !y _h no oxyg52 s !y c\ld n make ?+s decay4 ,n only w\ld ! dead plants & animals rema9 9 good condition1 b ! clo!s p 7 we>+ :5 !y dropp$ dead w\ld /ay unfad$ & bright color$ ?r\gh all ! /orms & sun%9e4 ,& ! iron poles & c> tracks & w9d[ b>s w\ld rema9 unru/$4 ,= blea*+ & ru/+ are sl[ k9ds ( oxidation or burn+ 7comb9+ ) oxyg574 ,"h are two exp]im5ts :i* %[ t y _c make ?+s burn unless y h oxyg5 to comb9e ) !m3 ,,exp]im5t #id4 ,light a c&le n m ?an #d in*es long & /& x on ! plate ( ! air pump4 ,cov] x ) ! bell j> & pump ! air out4 ,:at happ5s to ! flame8 ,,exp]im5t #ie4 ,fa/5 a piece ( c&le #c or #d in*es long to ! bottom ( a pan4 ,p\r wat] into ! pan until x is ab\t an in* deep4 ,light ! c&le4 ,turn an empty milk bottle upside d[n ov] ! c&le4 ,wat* ! flame4 ,leave ! bottle ov] ! c&le until ! bottle cools4 ,wat* ! wat] ar\nd ! bottom ( ! bottle4 ,lift ! bottle p>tly out ( ! wat]1 keep+ ! m\? "u wat]4 ,! bubbles t came out = a few seconds at ! beg9n+ ( ! exp]im5t 7 caus$ by ! air 9 ! bottle be+ heat$ & exp&$ by ! flame4 ,soon1 h[ev]1 ! oxyg5 9 ! air 0 us$ s fa/ t x made up = ?is expansion1 & ! bubbles /opp$ go+ out4 ,:5 practically all ! oxyg5 0 us$1 ! flame w5t out4 ,! c&le is made mo/ly ( a comb9ation ( hydrog5 & c>bon4 ,! hydrog5 comb9es ) "p ( ! oxyg5 9 ! air t is 9 ! bottle to =m a little wat]4 ,! c>bon comb9es ) ! re/ ( ! oxyg5 to make c>bon dioxid1 mu* ( :i* dissolves 9 ! wat] bel[4 ,s !re is practically empty space 9 ! bottle :]e ! oxyg5 01 & ! air outside =ces ! wat] up into ?is space4 ,! re/ ( ! bottle is fill$ ) ! nitrog5 t 0 9 ! air & t has rema9$ un*ang$4 ,ab\t h[ mu* ( ! air 0 oxyg5 is indicat$ by ! space t ! wat] fill$ aft] ! oxyg5 0 comb9$ ) ! c&le4 ,illu/ration3 ,,fig4 #afg4 ,! wat] rises 9 ! bottle aft] ! burn+ c&le uses up ! oxyg54 ,,c>bon ,,& ,,hydrog5 ,,! ,,*ief ,,elem5ts ,,9 ,,fuel4 ,c>bon & hydrog5 make up ! l>g] "p ( almo/ e sub/ance t is us$ = fuel1 includ+ gas1 gasol9e1 wood1 & s(t coal2 alcohol1 crude oil1 k]os5e1 pap]1 peat1 & ! acetyl5e us$ 9 automobile & bicycle lamps4 ,h>d coal1 coke1 & *>coal are1 h[ev]1 *iefly pla9 c>bon4 ,s9ce burn+ is simply ! comb9+ ( ?+s ) oxyg51 x is pla9 t :5 ! c>bon ( fuel jo9s oxyg5 we %all get c>bon dioxid 7,,co#b74 ,:5 ! hydrog5 9 ! fuel jo9s oxyg51 :at mu/ we get8 ,:5 ?+s d n burn up completely1 ! c>bon may be left beh9d z *>coal4 ,t is :at happ5s :5 food burns on ! /ove4 ,b if any?+ burns up entirely1 ! c>bon or *>coal burns too1 pass+ (f z ! invisible gas1 c>bon dioxid1 j z ! hydrog5 burns to =m /eam or wat]4 ,x is because almo/ e fuel =ms wat] :5 x burns1 t we f9d drops ( wat] ga!r+ on ! outside ( a cold kettle or cold flatiron if ei!r is put directly ov] a flame4 ,! hydrog5 9 ! fuel comb9es ) ! oxyg5 ( ! air to =m /eam4 ,z ! /eam /rikes ! cold kettle or iron1 x cond5ses & =ms drops ( wat]4 ,,no?+ ,,ev] ,,de/roy$4 ,"o important result ( ! discov]y t burn+ is only a comb9+ ( oxyg5 ) ! fuel 0 t p began to see t no?+ is ev] de/roy$4 ,!re is exactly z mu* c>bon 9 ! c>bon dioxid t floats (f f a fire z !re 0 9 ! wood t 0 burn$ up2 & !re is exactly z mu* hydrog5 9 ! wat] vapor t floats (f f ! fire z !re 0 9 ! wood4 ,*emi/s h caught all ! c>bon dioxid & ! wat] vapor & weigh$ !m & add$ _! weight to ! weight ( ! a%es2 & !y h f\nd !m to weigh ev5 m ?an ! orig9al piece ( wood1 because ( ! pres5ce ( ! oxyg5 t comb9$ ) !m 9 ! burn+4 ,if ev]y?+ 9 ! _w 7 to burn up1 us+ ! oxyg5 t is already "h1 ! _w w\ld n weigh "o ounce m or less ?an x does n[4 ,all ! elem5ts t 7 "h be=e w\ld /ill be "h2 b !y w\ld be comb9$ 9 diff]5t comp\nds4 ,in/ead ( wood & coal & oxyg5 we %\ld h wat] & c>bon dioxid2 in/ead ( diamonds1 we %\ld h j c>bon dioxid2 & s on ) ev]y?+ t c burn4 ,,:y ,,wat] ,,puts ,,out ,a ,,fire4 ,wat] puts out a fire because x w n let en\gh free oxyg5 get to ! wood1 or :atev] is burn+1 to comb9e ) x4 ,! oxyg5 t is lock$ up 9 a comp\nd1 l wat]1 y rememb]1 has lo/ its ability to comb9e ) o!r ?+s4 ,s& puts out a fire 9 ! same way t wat] does4 ,mo/ fire ext+ui%]s make a foam ( c>bon dioxid 7,,co#b7 :i* cov]s ! burn+ mat]ial & keeps ! free oxyg5 9 ! air f com+ ne> en\gh to comb9e ) x4 ,wat] w n put out burn+ oil1 h[ev]1 z ! oil floats up on top ( ! wat] & /ill comb9es ) ! oxyg5 9 ! air4 ,,:y ,,electric ,,lamps ,,are ,,usually ,,vacuums4 ,electric lamps usually h vacuums inside because ! filam5t gets s hot t x w\ld burn up if !re 7 any oxyg5 to comb9e ) x4 ,b 9 a globe conta9+ no oxyg5 ! filam5t may be made ev] s hot & x _c possibly burn4 ,high-p[] electric lamps are n made ) vacuums b are gas-fill$4 ,! gas t is (t5e/ put into lamps is nitrog51--! same gas t is mix$ ) ! oxyg5 9 air4 ,by tak+ all ! oxyg5 out ( a quantity ( air1 ! lamp manufactur]s c use 9 p]fect safety ! nitrog5 t is left4 ,x w n comb9e ) ! gl[+ filam5t4 ,!re is no oxyg5 to comb9e ) ! filam5t2 s ! lamp does n burn out4 ,,:at ,,flames ,,are4 ,:5 y look at a flame1 x seems z if fire 7 a real ?+ & n m]ely a process ( comb9+ some?+ ) oxyg54 ,! flame is a real ?+4 ,x is made up ( hot gases1 ris+ f ! hot fuel1 & x is usually fill$ ) t9y gl[+ p>ticles ( c>bon4 ,:5 y burn a piece ( wood1 ! heat p>tly sep>ates its elem5ts1 j z heat+ sug> sep>ates ! c>bon f ! wat]4 ,"s ( ! hydrog5 gas 9 ! wood & "s ( ! c>bon too are sep>at$ f ! wood by ! heat4 ,^! are pu%$ up by ! cool] air ar\nd & comb9e ) ! oxyg5 z !y rise4 ,! hydrog5 comb9es m easily ?an ! c>bon2 "p ( ! c>bon may rema9 beh9d z *>coal if y\r wood does n all burn up1 & _m ( ! small] c>bon p>ticles only gl[ 9 ! burn+ hydrog51 in/ead ( burn+4 ,t is :at makes ! flame yell[4 ,if y hold any?+ :ite ov] a yell[ flame1 x w soon be cov]$ ) black soot1 :i* is c>bon4 ,,:at ,,smoke ,,is4 ,smoke consi/s mo/ly ( little specks ( unburn$ c>bon4 ,t is :y x is gray or black4 ,:5 y h black smoke1 y may always be sure t "s ( ! c>bon p>ticles are n comb9+ prop]ly ) oxyg54 ,yell[ flames are usually smoky2 t is1 !y usually are full ( unburn$ bits ( c>bon t float (f above ! flame4 ,b by lett+ en\gh air 9 ) ! flame1 x is possible to make all ! little pieces ( c>bon burn 7comb9e ) ! oxyg5 ( ! air7 be=e !y leave ! heat ( ! burn+ hydrog54 ,t is :y k]os5e lamps d n smoke :5 ! *imney is on4 ,! *imney keeps all ! hot gases toge!r1 & ?is causes a draft ( fre% air to bl[ up ! *imney to pu% ! hot gases on up4 ,! fre% air bl[+ up pa/ ! flame gives pl5ty ( oxyg5 to comb9e ) ! c>bon4 ,! drum "p ( an oil heat] acts 9 ! same way2 :5 ! drum is op51 ! heat] smokes badly2 :5 x is clos$ up1 en\gh air goes pa/ ! flame to burn up all ! c>bon4 ,b if y turn ei!r lamp or heat] too high1 x w smoke anyway2 y _c get en\gh air ?r\gh to comb9e ) all ! c>bon4 ,! hotte/ flames are ! blue flames4 ,t is because 9 a blue flame all ! c>bon is burn+ up along ) ! hydrog5 ( ! fuel--bo? are comb9+ ) ! oxyg5 ( ! air z rapidly z possible4 ,a gas or gasol9e /ove is s arrang$ t air is f$ into ! burn] ) ! gas4 ,y w see ?is 9 ! foll[+ exp]im5t3 ,,exp]im5t #if4 ,light ! ,buns5 burn] 9 ! laboratory4 ,op5 wide ! little valve 9 ! bottom4 ,n[ put y\r f+] & ?umb ov] ! hole 9 ! bottom ( ! burn]4 ,:at happ5s to ! flame8 ,turn ! valve s t x w close ! hole 9 ! same way4 ,n[ hold a :ite sauc] ov] ! flame1 be+ c>eful n to get x hot en\gh to break4 ,:at is ! black /uff on ! bottom ( ! sauc]8 ,exam9e ! gas plate 7small gas /ove7 9 ! laboratory4 ,light x1 & see if y c f9d ! place :]e ! air is f$ 9 ) ! gas4 ,close ?is place & see :at happ5s4 ,op5 x wid] & see :at happ5s4 ,if ! air op5+ is too l>ge1 ! flame bl[s2 !re is too mu* cold air com+ 9 ) ! gas1 & y\r flame is n z hot z x w\ld be if x did n bl[4 ,also1 ! /ove is liable to back-fire 7cat* fire at ! air op5+7 :5 ! air op5+ is too wide4 ,illu/ration3 ,,fig4 #afh4 ,! ,buns5 burn] smokes :5 ! air holes are clos$4 ,,application #fi4 ,an oil lamp tipp$ ov] & ! burn+ oil spread ov] ! floor4 ,ne> by 7 a pail ( wat]1 a pan ( a%es1 a rug1 & a seltz] siphon4 ,:i* ( ^! might h be5 us$ to advantage 9 putt+ out ! fire8 ,,application #gj4 ,my f+] 0 burn$4 ,i want$ ! fle% ar\nd x to heal & new sk9 cells to live & gr[ rapidly ar\nd ! burn4 ,put a rubb] f+] cot on ! f+] & keep all air out1 "o fri5d advis$ me4 ,air causes decay & w !re=e be bad = ! burn4 ,he's wrong2 y %\ld b&age x ) clean clo?2 y want air to rea* ! f+]1 ,i've he>d1 said ano!r fri5d4 ,oh1 no1 y don't2 air makes ?+s burn1 & ! burn w !re=e get worse1 /ill ano!r "o said4 ,:at %\ld ,i h done8 ,,application #ga4 ,two /ud5ts 7 discuss+ h[ coal 0 =m$4 ,! trees mu/ h fall5 into wat] & be5 completely cov]$ by x1 or !y w\ld h decay$1 said "o4 ,wat] makes ?+s decay m quickly2 !re mu/ h be5 a dr\ght & ! trees mu/ h fall5 on dry gr\nd1 said ! second4 ,:i* 0 "r8 ,illu/ration3 ,,fig4 #afi4 ,regulat+ ! air op5+ 9 a gas /ove4 ,,application #gb4 ,a gas /ove _h a yell[ flame4 ,9 front1 by ! h&les1 0 a metal disk ) holes s arrang$ t turn+ x to ! left all[$ air to mix ) ! gas on ! way to ! flame1 & turn+ x to ! "r %ut ! air (f 7see ,fig4 #agj74 ,"o memb] ( ! family said1 ,turn ! disk to ! left & let m air mix ) ! gas4 ,b ano!r object$4 ,x has too mu* air already2 t's :y ! flame is yell[4 ,turn x to ! "r & %ut (f ! air f bel[4 ,y're bo? wrong4 ,:y d y want to *ange x8 said a ?ird memb] ( ! family4 ,! yell[ flame is ! hotte/1 anyway4 ,c't y see t ! yell[ flame gives m light8 ,& don't y "k t light is j a k9d ( radiant heat8 ,( c\rse ! yell[ flame is ! hotte/4 ,leave ! /ove alone4 ,:o 0 "r8 ,illu/ration3 ,,fig4 #agj4 ,! air op5+s 9 ! front ( a gas /ove4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dda4 ,iron tracks are weld$ toge!r ) an electric arc4 #ddb4 ,! cool mirror 9 a ba?room becomes cov]$ ) moi/ure :5 y take a hot ba?4 #ddc4 ,?is prev5ts y f see+ y\rself 9 ! mirror4 #ddd4 ,c>bon dioxid has oxyg5 9 x1 yet a burn+ mat* dropp$ into a bottle ( x w g out4 #dde4 ,a %ip t s9ks to ! bottom ( ! ocean does n decay4 #ddf4 ,:5 wom5 put _! hair 9 curl]s1 !y usually moi/5 ! hair slightly4 #ddg4 ,to dry a pan aft] wa%+ x1 a p]son (t5 sets x on ! hot /ove = a few m9utes4 #ddh4 ,:5 y put a kettle ( cold wat] ov] a gas flame1 drops ( wat] appe> on ! l[] "p ( ! sides ( ! kettle4 #ddi4 ,electric p[] plants are (t5 situat$ :]e runn+ wat] w turn ! dynamo4 ,expla9 ! necessity ( turn+ ! dynamo4 #dej4 ,we make c>bon dioxid by burn+ c>bon1 b y _c put diff]5t ?+s toge!r to make c>bon4 ,,section #dh4 ,*emical *ange caus$ by heat4 ,:y d y h to /rike a mat* to make x burn8 ,h[ does pull+ ! trigg] make a gun g (f8 ,:at makes cook$ foods ta/e diff]5t f raw ones8 ,has x /ruck y z /range t we d n all burn up1 s9ce burn+ is a comb9+ ) oxyg51 & we are walk+ ar\nd 9 oxyg5 all ! "t8 ,! only reason we d n burn up is t x usually requires heat to />t a *emical *ange4 ,y already "k ?is 9 a practical way4 ,y "k t y h to rub ! head ( a mat* & get x hot be=e x w beg9 to burn2 t gunp[d] does n g (f unless y heat x by ! sudd5 bl[ ( ! gun hamm] :i* y release :5 y pull ! trigg]2 t y h to conc5trate ! sun's rays ) a magnify+ glass to make x set a piece ( pap] on fire2 & t to *ange raw food into food t ta/es pleasant y h to heat x4 ,if heat did n />t *emical *ange1 y c\ld nev] cook food1--p>tly because ! fire w\ld n burn1 & p>tly because ! food w\ld n *ange its ta/e ev5 if heat$ by electricity or conc5trat$ sunlight4 ,"h is an exp]im5t to %[ t gas w n burn unless x gets hot en\gh3 ,,exp]im5t #ig4 ,hold a wire scre5 #b or #c in*es above ! m\? ( a ,buns5 burn]4 ,turn on ! gas & light a mat*1 hold+ ! light$ mat* above ! scre54 ,:y1 d y suppose1 does ! gas bel[ ! scre5 n burn8 ,hold a light$ mat* to ! gas bel[ ! scre54 ,does x burn n[8 ,! reason ! scre5 kept ! gas bel[ x f cat*+ fire al?\gh ! gas above x 0 burn+ 0 ?is3 ,! heat f ! flame above 0 conduct$ out to ! sides by ! wire scre5 z soon z x rea*$ ! scre52 s v little heat c\ld get ?r\gh ! scre5 to ! gas bel[4 ,!re=e ! gas bel[ ! scre5 nev] got hot en\gh = ! *emical *ange ( oxidation1 or burn+1 to take place4 ,s ! gas bel[ x did n cat* fire4 ,ano!r simple exp]im5t ) ! ,buns5 burn]1 t %[s ! same ?+ 9 a diff]5t way1 is ?is3 ,illu/ration3 ,,fig4 #aga4 ,:y doesn't ! flame above ! wire gauze set fire to ! gas bel[8 ,,exp]im5t #ih4 ,light ! ,buns5 burn]4 ,op5 ! air valve at ! bottom all ! way4 ,hold ! wood end ( a mat* 7n ! head7 9 ! c5t] ( ! inn] gre5i% cone ( flame1 ab\t half an in* above ! m\? ( ! burn]4 ,does ! "p ( ! mat* 9 ! c5t] ( ! flame cat* fire8 ,does ! "p on ! edge8 ,:at d y suppose is ! reason = ?is8 ,:]e are ! cold gas & air ru%+ 98 ,c !y get hot all at once1 or w !y h to travel out or up a way be=e !y h "t to get hot en\gh to comb9e8 ,illu/ration3 ,fig4 #agb4 ,! "p ( ! mat* 9 ! middle ( ! flame does n burn4 ,,application #gc4 ,expla9 :y boil$ milk has a diff]5t ta/e f fre% milk2 :y bl[+ on a mat* w put x out2 :y food gets black if x is left on ! /ove too long4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dea4 ,:5 y want bread d\gh to rise1 y put x 9 a w>m place4 #deb4 ,ink left long 9 an op5 inkwell becomes ?ick4 #dec4 ,a ball b\nces up :5 y ?r[ x d[n4 #ded4 ,:5 ! w>m ocean air bl[s ov] ! cool l& 9 ! e>ly morn+1 !re is a heavy fog4 #dee4 ,/rik+ a mat* makes x burn4 #def4 ,:5 y h some?+ h>d to cut1 y put x 9 ! "p ( ! scissors ne>e/ ! h&les4 #deg4 ,a magnet held ov] iron fil+s makes !m leap up4 #deh4 ,di%es 9 :i* fl\r ?ick5+ or d\gh has be5 mix$ %\ld be wa%$ out ) cold wat]4 #dei4 ,a wool5 sweat] is liable to /ret* out ( %ape aft] be+ wa%$4 #dfj4 ,:5 a telegraph op]ator presses a key 9 8 set1 a piece ( iron is pull$ d[n 9 ! set ( ano!r op]ator4 ,,section #di4 ,*emical *ange caus$ by light4 ,h[ c a cam]a take a picture8 ,:y does clo? fade 9 ! sun8 ,:at makes freckles8 ,if light c\ld n help *emical *ange1 no?+ w\ld ev] fade :5 hung 9 ! sun2 wall pap] & curta9s w\ld be z bright color$ aft] #bj ye>s z on ! day !y 7 put up1 if !y 7 kept clean2 y w\ld nev] become freckl$1 tann$1 or sunburn$2 all photograph]s & mov+-picture op]ators w\ld h to g out ( bus9ess2 b wor/ ( all1 e gre5 plant w\ld imm$iately /op gr[+ & w\ld soon die4 ,!re=e1 all c[s & horses & o!r plant-eat+ animals w\ld die2 & !n ! fle%-eat+ animals w\ld h no?+ to eat & !y w\ld die2 & !n all p w\ld die4 ,y w be able bett] to und]/& :y all ?is w\ld happ5 aft] y d ! foll[+ exp]im5ts1 ! fir/ ( :i* w %[ t light helps ! *emical *ange call$ blea*+ or fad+4 ,,exp]im5t #ii4 ,r9se two small pieces ( light-color$ clo?4 7,lav5d] is a good color = ?is exp]im5t47 ,lay "o piece 9 ! bright sun to dry2 dry ! o!r 9 a d>k cab9et or closet4 ,! next day comp>e ! two clo?s4 ,:i* has kept its color ! bett]8 ,if ! diff]5ce is n m>k$1 repeat ! exp]im5t = #b or #c days 9 succession1 putt+ ! same clo?1 wet1 9 ! sun ea* "t4 ,blea*+ is usually a v sl[ k9d ( burn+4 ,x is ! dye t is oxidiz$ 7burn$71 n ! clo?4 ,mo/ dyes w comb9e ) ! oxyg5 9 ! air if !y are expos$ to ! sunlight4 ,! dampness quick5s ! action4 ,,:y ,,"s ,,p ,,freckle ,,9 ,,! ,,sun4 ,:5 ! sunlight falls = a long "t on ! sk91 x (t5 causes ! cells 9 ! "u "p ( ! sk9 to produce "s d>k color+ matt]1 or pigm5t4 ,?is d>k pigm5t %[s ?r\gh ! out] lay] ( sk91 & we call ! little spots ( x freckles4 ,"s p are born ) ^! pigm5t spots2 b :5 ! freckles come out f long exposure to ! sunlight1 !y are an example "r 9 our own sk9s ( *emical *ange caus$ by ! action ( light4 ,tan also is due to pigm5t 9 ! sk9 & is caus$ by light4 ,! next exp]im5ts ) _! explanations w %[ y h[ cam]as c take pictures4 ,if y are n int]e/$ 9 kn[+ h[ photographs are made1 d ! exp]im5ts & skip ! explanations d[n to ! middle ( page #ccb4 ,,exp]im5t #ajj4 ,dissolve a small cry/al ( silv] nitrate 7,ag,n,o#c7 9 ab\t half an in* ( pure wat] 9 ! bottom ( a te/ tube4 ,di/ill$ wat] is be/ = ?is purpose4 ,n[ add "o drop ( hydro*loric acid 7,h,cl74 ,! :ite p[d] =m$ is a silv] salt1 call$ silv] *lorid 7,ag,cl72 ! re/ ( ! liquid is n[ a dilut$ nitric acid 7,,hno#c74 ,p\r ! susp5sion ( silv] *lorid 7,ag,cl7 on a piece ( blott+ pap] or on a pap] t[el1 s t ! wat] w be absorb$4 ,spread ! rema9+ :ite pa/e ( silv] *lorid 7,ag,cl7 out ov] ! blott] z well z y c4 ,cov] "p ( x ) a key 7or any?+ t w %ut (f ! light71 & leave ! o!r "p expos$4 ,if ! sun is %9+1 put ! blott] 9 ! sunlight = #e m9utes4 ,o!rwise1 let z mu* daylight fall on x z possible = ab\t #aj m9utes4 ,n[ take ! key (f ! "p ( ! silv] *lorid 7,ag,cl7 t x 0 cov]+ & comp>e ?is ) ! "p t 0 expos$ to ! light4 ,:at has ! light done to ! silv] *lorid 7,ag,cl7 t x %one on8 ,:at has happ5$ is t ! light has made ! silv] 7,ag7 sep>ate f ! *lor9e 7,cl7 ( ! silv] *lorid 7,ag,cl74 ,*emi/s w\ld write ?is3 ,ag,cl - ,ag ,cl4 ,t is1 silv] *lorid 7,ag,cl7 has *ang$ into silv] 7,ag7 & *lor9e 7,cl74 ,*lor9e1 z y "k1 is a poison\s gas1 & x floats (f 9 ! air1 leav+ ! f9e p>ticles ( silv] beh9d4 ,:5 silv] is divid$ into v t9y p>ticles1 x absorbs light in/ead ( reflect+ x2 s x looks d>k gray or black4 ,,h[ ,,photographs ,,are ,,made4 ,all photography dep5ds on ?is action ( light4 ,! plates or films are coat$ ) a silv] salt1--usually a m s5sitive salt ?an silv] *lorid4 ,?is is expos$ to ! light t %9es ?r\gh ! l5s ( ! cam]a4 ,z y h le>n$1 ! l5s br+s ! light f ! object to a focus & makes an image on ! film or plate4 ,! light p>ts ( ?is image w *ange ! silv] salt to silv]2 ! d>k p>ts w n *ange x4 ,s :]ev] !re is a :ite place on ! object y are photograph+1 !re w be a d>k pat* ( silv] on ! film or plate1 & :]ev] !re is a d>k spot on ! object1 !re w be no *ange on ! film or plate4 ,illu/ration3 ,,fig4 #agc4 ,! silv] salt on ! pap] rema9s :ite :]e x 0 %ad$ by ! key4 ,z a matt] ( fact1 ! film or plate is expos$ su* a %ort "t t !re is n "t = ! *ange to be complet$4 ,s ! photograph] develops ! negative2 he wa%es x 9 "s *emicals t f9i% ! process :i* ! light />t$4 ,if he expos$ ! :ole plate to ! light n[1 h[ev]1 all ! un*ang$ p>ts ( ! silv] salt w\ld also be *ang$ by ! light1 & !re w\ld be no picture left4 ,s be=e he lets any light %9e on x1 except r$ light :i* has no effect on ! silv] salt1 he dissolves (f all ! :ite un*ang$ "p ( ! silv] salt1 9 ano!r k9d ( *emical call$ ! fix+ ba?4 ,?is is call$ fix+ ! negative4 ,! only tr\ble ) ! picture n[ is t :]ev] !re %\ld be a pat* ( :ite1 !re is a pat* ( d>k silv] p>ticles2 & :]ev] !re %\ld be a d>k place1 !re is j ! cle> glass or celluloid1 ) all ! silv] salt dissolv$ (f4 ,?is k9d ( picture is call$ a negative2 ev]y?+ is j ! opposite %ade f :at x %\ld be4 ,a :ite man dress$ 9 a black suit looks l a negro dress$ 9 a :ite suit4 ,,h[ ,a ,,photographic ,,pr9t ,,is ,,made4 ,! negative n only has ! lights & %ad[s rev]s$1 b x is on celluloid or glass1 & except = mov+ pictures & /]eopticons1 we usually want ! picture on pap]4 ,s a pr9t is made ( ! negative4 ,! next exp]im5t w %[ y h[ ?is is done4 ,,exp]im5t #aja4 ,9 a d>k room or closet1 take a %eet ( bluepr9t pap] f ! package1 aft]w>ds clos+ ! package c>efully s t no light c get to ! pap]s inside4 ,hold ! piece ( bluepr9t pap] "u y\r wai/ or coat1 to keep x d>k :5 y g into ! light4 ,n[ lay x1 gre5i% side d[nw>d1 on a negative4 ,hold ! two toge!r1 or place !m 9 a pr9t+ frame1 & turn !m ov] s t ! light w %9e ?r\gh ! negative ^u ! gre5i% side ( ! bluepr9t pap]4 ,be sure t ! pap] is held firmly aga9/ ! negative & n mov$ ar\nd4 ,let ! sun %9e ?r\gh ! negative ^u ! pap] = #a or #b m9utes accord+ to ! brightness ( ! sun1 or let ! gray light ( ! sky1 if x is cl\dy1 %9e on x = #e or #aj m9utes4 ,n[ quickly put ! bluepr9t pap] 7n ! negative7 into a bas9 ( wat]1 face d[n4 ,wa% = a c\ple ( m9utes4 ,turn x ov] & exam9e x4 ,if x has be5 expos$ to ! light too long1 x w be d>k2 if x has be5 expos$ too %ort a "t1 x w be too light2 9 ei!r case1 if ! pr9t is n cle>1 repeat ) a fre% piece ( bluepr9t pap]1 alt]+ ! "t ( exposure to ! sunlight to improve ! pr9t4 ,y c make pretty outl9e pictures ( leaves & press$ fl[]s1 or ( lace1 by lay+ ^! on ! bluepr9t pap] 9 place ( ! negative & 9 o!r respects do+ z direct$ above4 ,illu/ration3 ,,figs4 #agd & #age4 ,:]e ! negative is d>k1 ! pr9t is light4 ,9 mak+ bluepr9ts y are *ang+ an iron salt in/ead ( a silv] salt1 by ! action ( light4 ,regul> photographic pr9ts are usually made on pap] treat$ ) a silv] salt r ?an ) iron salt1 & sometimes a gold or plat9um salt is us$4 ,b ^! o!r salts h to be wa%$ (f ) *emicals s9ce !y d n come (f 9 wat]1 z ! un*ang$ "p ( ! iron salt comes (f :5 y fix ! bluepr9t pap] 9 ! wat] ba?4 ,s9ce ! light _c get ?r\gh ! black "p ( a negative1 ! coat+ on ! pap] beh9d t "p is n affect$ & x /ays light color$2 & s9ce ! light c get ?r\gh ! cle> p>ts ( ! negative1 ! coat+ on ! pap] back ( ^? p>ts is affect$ & becomes d>k4 ,!re=e1 ! pr9t is "r side out1--!re is a light place on ! pr9t = e :ite place on ! object photograph$1 & !re is a d>k place on ! pr9t = e black place on ! object4 ,mov+-picture films are pr9t$ f "o film to ano!r1 j z y pr9t$ f a negative to a piece ( pap]4 ,! negative is tak5 on "o film1 !n ?is is pr9t$ on ano!r film4 ,! second film is "r side out4 ,,light ,,& ,,! ,,manufacture ,,( ,,food ,,9 ,,plants4 ,mu* ! mo/ important *emical effect ( light1 h[ev]1 is n 9 mak+ photographs1 9 blea*+ ?+s1 or 9 burn+ y\r sk94 ,x is 9 ! putt+ toge!r ( c>bon & wat] to make sug> 9 plants4 ,plants get wat] 7,h#b,o7 f ! e>? & c>bon dioxid 7,,co#b7 f ! air4 ,:5 ! sun %9es on *lorophyll1 ! gre5 sub/ance 9 plants1 ! *lorophyll puts !m toge!r & makes sug>4 ,! plant *anges ?is sug> into />* & o!r foods1 & into ! tissues ( ! plant itself4 ,no?+ 9 ! _w c put c>bon dioxid & wat] toge!r & make food out ( !m except c]ta9 bact]ia & ! *lorophyll ( plants4 ,& light is absolutely necess>y = ?is *emical action4 ,try ?is exp]im5t3 ,,exp]im5t #ajb4 ,p9 toge!r two pieces ( cork on opposite sides ( a leaf t is expos$ to ! sun4 ,! next day take ?is leaf f ! plant & heat x 9 a beak] ( alcohol until ! gre5 color+ matt] is remov$ f ! leaf4 ,!n place ! leaf 9 a glass ( wat] t conta9s iod9e4 ,! iod9e w color ! leaf d>k :]e ! cells conta9 />*4 7,see ,exp]im5t #aae1 page #cgc47 ,is />* =m$ :]e ! light does n rea* ! leaf8 ,no plant c make food except ) ! help ( light4 ,! "p ( ! plant t c put c>bon dioxid & wat] toge!r is ! gre5 /uff or *lorophyll1 & ?is c "w only :5 light is %9+ on x4 ,s all plants w\ld die )\t light4 ,b if all plants %\ld die1 all animals w\ld die also1 = animals _c make food out ( c>bon dioxid & wat]1 z !y d n h ! *lorophyll t puts ^! ?+s toge!r4 ,a lion does n live on leaves1 x is true1 b he lives on de] & o!r animals t d live on leaves & plants4 ,if ! plants di$1 all plant-eat+ animals w\ld die4 ,!n !re w\ld be no?+ = ! fle%-eat+ animals to eat except ea* o!r1 & 9 "t no animals w\ld be left 9 ! _w4 ,! same ?+ w\ld happ5 to ! fi%4 ,& man1 ( c\rse1 c\ld no long] exi/4 ,! food supply ( ! _w dep5ds on ! fact t light c />t *emical *ange4 ,,oxyg5 ,,releas$ ,,9 ,,! ,,manufacture ,,( ,,plant ,,food4 ,besides 9 "o way or ano!r giv+ u all ( our food1 plants1 help$ by light1 also give u mo/ ( ! free oxyg5 t we brea!4 ,we & all animals get ! en]gy by :i* we live by comb9+ oxyg5 ) ! hydrog5 ( our food 7=m+ wat]7 & by comb9+ oxyg5 ) ! c>bon 9 our food 7=m+ c>bon dioxid74 ,?is comb9+ 7burn+ or oxidiz+7 gives u our body heat & ! en]gy to move4 ,! free oxyg5 is c>ri$ to ! diff]5t p>ts ( our bodies by ! r$ blood corpuscles t float 9 ! liquid "p ( ! blood4 ,! liquid "p ( ! blood also c>ries ! food to ! diff]5t p>ts ( ! body1 & ! food conta9s ! c>bon & hydrog5 t is to be burn$4 ,!n 9 a muscle1 = in/ance1 ! oxyg5 t has be5 c>ri$ by ! corpuscles comb9es ) ! c>bon to =m c>bon dioxid1 & ) ! hydrog5 to =m wat]4 ,! corpuscles c>ry "p ( ! c>bon dioxid back to ! lungs1 & ! wat] is c>ri$ ) o!r wa/es & ! re/ ( ! c>bon dioxid 9 ! liquid "p ( ! blood4 ,9 ! lungs ! c>bon dioxid is ex*ang$ = ! free oxyg5 we h j inhal$1 & we exhale ! c>bon dioxid4 ,a good deal ( wat] is also brea!d out1 z y c tell f ! way ! mi/ ga!rs on a w9d[ pane :5 y bl[ on x4 ,if !re 7 only animals 7includ+ p7 9 ! _w1 all ! free oxyg5 9 ! air w\ld 9 "t be comb9$ by ! animals ) hydrog5 to make wat] & ) c>bon to make c>bon dioxid 7,,co#b74 ,z animals _c brea! wat] & _c get any good f c>bon dioxid1 !y w\ld all smo!r4 ,b ! plants1 z we h already said1 use c>bon dioxid 7,,co#b7 & wat] 7,h#b,o7 to make food4 ,!y d n ne$ s mu* oxyg51 & s !y set "s ( x free4 ,! c\ntless plants 9 ! _w set ! oxyg5 free z rapidly z ! c\ntless animals comb9e x ) hydrog5 to make wat] & ) c>bon to make c>bon dioxid4 ,s9ce ! wat] & c>bon dioxid are ! ma9 ?+s a plant ne$s to make its food1 ! animals really are z helpful to ! plants z ! plants are to ! animals4 ,= ! animals furni% ! mat]ials to ! plants = mak+ _! food 9 ex*ange = ! ready-made food furni%$ by ! plant4 ,& bo? plants & animals w\ld die if light /opp$ help+ to br+ ab\t *emical *ange4 ,,application #gd4 ,expla9 :y ! he>t ( a cabbage is :ite in/ead ( gre5 l ! outside leaves2 :y a photograph] works 9 a d>k room ) only a ruby light2 :y y get freckl$ 9 ! sun4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dfa4 ,if a p9 is put ?r\gh a lamp cord1 a fuse is likely to bl[ out4 #dfb4 ,! wall pap] back ( a picture is (t5 d>k] ?an t on ! re/ ( ! wall4 #dfc4 ,if y wet an eras]1 x rubs ?r\gh ! pap]4 #dfd4 ,clo!s are hot aft] be+ iron$4 #dfe4 ,if y drop c&le grease on y\r clo!s1 y c remove ! grease by plac+ a blott] ov] x & press+ ! blott] ) a w>m iron4 #dff4 ,mill9]s cov] hats t are on display 9 w9d[s :]e ! sun %9es 9 on ! hats4 #dfg4 ,y pull d[n on a rope :5 y try to climb x4 #dfh4 ,9 tak+ a picture1 y expose ! s5sitive film or plate to ! light = a %ort "t4 #dfi4 ,good cam]as h an adju/able front "p s t ! l5s may be mov$ ne>] to ! plate or film1 or f>!r f x1 accord+ to ! di/ance ( ! object to be photograph$4 #dgj4 ,a p5cil has to be re%>p5$ frequ5tly :5 x is mu* us$4 ,,section #ej4 ,*emical *ange caus$ by electricity4 ,h[ are /orage batt]ies *>g$8 ,h[ is silv] plat+ done by electricity8 ,y h already done an exp]im5t %[+ t electricity c />t *emical *ange1 = y *ang$ wat] into hydrog5 & oxyg5 by pass+ a curr5t ( electricity ?r\gh ! wat]4 ,! plat+ ( metals is made possible by ! fact t electricity helps *emical *ange4 ,y c nickel plate a piece ( copp] 9 ! foll[+ mann]3 ,,exp]im5t #ajc4 ,dissolve a few gre5 cry/als ( d\ble nickel salts 9 wat]1 until ! wat] is a cle> gre54 ,! wat] %\ld be ab\t #b or #c in*es deep 9 a glass or *9a b[l t is n less ?an #e in*es across4 ,lay two b>e copp] wires across ! b[l1 ab\t #c in*es ap>t1 z %[n 9 ,figure #agg4 ,connect ! positive wire f a /orage batt]y1 or ! wire f ! c>bon ( a batt]y ( ?ree or f\r cells1 to an end ( "o b>e wire4 ,connect ! negative wire f ! /orage or ! negative wire f ! z9c ( ! o!r batt]y to an end ( ! second b>e wire4 ,n[ fa/5 a f9e b>e wire #e or #f in*es long ar\nd a small piece ( copp]1 & ano!r l x ar\nd a piece ( nickel1 z %[n 9 ,figure #agf4 ,!n put ! piece ( copp] 9 ! bottom ( an evaporat+ di%1 ) ! wire hang+ out1 z 9 ,figure #agg4 ,illu/ration3 ,,fig4 #agf4 ,! copp] & ! nickel cube ready to hang 9 ! cleans+ solution4 ,illu/ration3 ,,fig4 #agg4 ,clean+ ! copp] 9 acids4 ,p\r ov] ! piece ( copp] en\gh ( ! cleans+ solution to cov] x4#i ,! cleans+ solution conta9s /rong acids4 ,if y get any on y\r sk9 or clo!s1 wa% x (f imm$iately ) ammonia or soda4 ,z soon z ! copp] is bright & clean1 take x out ( ! cleans+ solution & susp5d x by ! negative wire 9 ! gre5 nickel solution4 ,y c tell if y h x on ! negative wire1 = 9 t case bubbles w rise f x dur+ ! exp]im5t4 ,! copp] %\ld be entirely cov]$ by ! nickel solution1 b %\ld n t\* ! bottom or sides ( ! b[l4 ,p\r ! cleans+ solution f ! evaporat+ di% back into ! bottle4 ,susp5d ! nickel1 9 ! same way z ! copp]1 f ! positive wire cross+ ! b[l4 ,:5 set up1 ! app>atus %\ld appe> z %[n 9 ,figure #agh4 ,footnote #i3 ,! =mula = mak+ ! cleans+ solution is z foll[s3 #a cup wat]4 #a cup conc5trat$ sulfuric acid4 #a cup conc5trat$ nitric acid4 #a teaspoonful conc5trat$ hydro*loric acid4 ,! sulfuric & nitric acids mu/ be measur$ 9 glass or *9a cups1 & ! hydro*loric acid mu/ be measur$ 9 a silv]-plat$ spoon or 9 glass--n 9 t94 ,illu/ration3 ,,fig4 #agh4 ,plat+ ! copp] by electricity4 ,turn on ! electricity4 ,if ! copp] becomes black in/ead ( silv]y1 clean x aga9 9 ! cleans+ solution1 & move ! two b>e wires mu* f>!r ap>t1--practically ! full wid? ( ! b[l4 ,if ! copp] /ill turns black1 x means t too mu* electricity is fl[+4 ,9 t case use few] batt]ies4 ,! electricity has />t$ two *emical *anges4 ,x has made "p ( ! piece ( nickel comb9e ) "p ( ! solution ( nickel salt to =m m nickel salt1 & x has made "s ( ! nickel salt ar\nd ! copp] *ange into metallic nickel4 ,!n ! negative electricity 9 ! copp] has attract$ ! positive bits ( nickel metal made f ! nickel salt1 & made !m cl+ to ! copp]4 ,if !re is no dirt or grease on ! copp]1 ! p>ticles ( nickel get s close to x t !y /ick by adhesion1 ev5 aft] ! electric attraction has ceas$4 ,?is leaves ! copp] nickel-plat$1 b to make x %9y ! nickel plat+ mu/ be poli%$4 ,silv] plat+ & gold plat+ are done sub/antially 9 ! way t y h done ! nickel plat+1 only gold salt or silv] salt is us$ in/ead ( nickel salt4 ,j z electricity helps *emical *anges 9 plat+1 x helps *anges 9 a /orage batt]y4 ,b 9 ! /orage batt]y ! new comp\nds =m$ by *>g+ ! batt]y *ange back aga9 & g5]ate electricity :5 ! poles ( ! batt]y are connect$ ) ea* o!r by a good conductor4 ,,application #ge4 ,expla9 h[ spoons c be silv] plat$2 h[ wat] c be *ang$ into hydrog5 & oxyg54 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dga4 ,clo!s dry be/ 9 ! sun & w9d4 #dgb4 ,pro(s ( photographs t h n be5 ?or\ghly fix$ fade if left out ( _! envelope4 #dgc4 ,bl[+ a mat* puts x out1 yet a good draft is necess>y = a hot fire4 #dgd4 ,a cup does n naturally fall ap>t1 yet aft] x is brok5 x falls ap>t ev5 if y fit ! pieces toge!r aga94 #dge4 ,crayon leaves m>ks on a blackbo>d4 #dgf4 ,a bak$ potato ta/es v diff]5t f a raw "o4 #dgg4 ,an air-fill$ automobile tire is h>d] at noon ?an 9 ! e>ly morn+4 #dgh4 ,:5 a live trolley wire breaks & falls to ! /reet1 x becomes s hot t x burns4 #dgi4 ,glass j>s ( fruit %\ld be kept 9 a fairly d>k place4 #dhj4 ,y wa% di%es 9 hot wat]4 ,,section #ea4 ,*emical *ange releases en]gy4 ,:y is fire hot8 ,:at makes gl[worms gl[8 ,:y does cold quicklime boil :5 y p\r cold wat] on x8 ,if no en]gy 7 releas$ by *emical *ange1 we %\ld run d[n l clocks1 & c\ld nev] be w\nd up aga94 ,we c\ld brea!1 b to d s w\ld d u no m good ?an x w\ld if oxyg5 c\ld n comb9e ) ?+s4 ,oxidation w\ld g on 9 our bodies1 b x w\ld nei!r keep u w>m nor help u to move4 ,a few spasmodic j]ks ( our he>ts1 a few gasps ) our lungs1 & !y w\ld /op1 z ! muscles w\ld h no en]gy to keep !m go+4 ,! sunlight might cont9ue to w>m ! e>?1 z we are n sure t ! sun gets any ( its heat f *emical *ange4 ,b fires1 :ile !y w\ld burn = an in/ant1 w\ld be absolutely cold2 no en]gy w\ld be giv5 out by ! fuel comb9+ ) oxyg54 ,b ! fires c\ld n burn long1 because !re w\ld be no?+ to keep ! gases & fuel hot en\gh to make !m comb9e ) ! oxyg54 ,ev5 dur+ ! in/ant t a fire la/$ x w\ld be invisible1 = x w\ld give (f no light if no en]gy 7 releas$ by ! *emical *ange4 ,only electric lights & heat]s w\ld cont9ue to "w1 & ev5 "s ( ^! w\ld fail4 ,! electric motors 9 subm>9es & electric automobiles w\ld in/antly /op2 batt]y fla%lights w\ld g out z quickly z ! fire2 no doorbells w\ld r+4 ,9 %ort1 all =ms ( electric batt]ies w\ld /op s5d+ curr5ts ( electricity out ?r\gh _! wires1 & ev]y?+ dep5d+ ^u batt]ies w\ld /op runn+4 ,a fire gives out heat & light2 bo? are k9ds ( en]gy4 ,& x is ! electric en]gy caus$ by ! *emical *ange 9 batt]ies t runs subm>9es1 electric automobiles1 fla%lights1 & doorbells4 ,s9ce burn+ 7oxidation7 is simply a =m ( *emical *ange1 x is n difficult to realize t *emical *ange releases en]gy4 ,,:y ,,gl[worms ,,gl[4 ,:5 a gl[worm gl[s at night1 or :5 ! head ( a mat* gl[s z y rub x on y\r wet h& 9 ! d>k1 we call ! light phosphoresc5ce4 ,! "n phosphorus means light-be>+1 & any?+ l ! elem5t phosphorus1 t gl[s )\t actively burn+1 is said to be phosphoresc5t4 ,mat* heads h phosphorus 9 !m4 ,phosphoresc5ce is almo/ always caus$ by *emical *ange4 ,! en]gy releas$ is a dim light1 n heat or electricity4 ,sometimes millions ( microscopic sea animals make ! sea wat] 9 w>m regions phosphoresc5t4 ,!y1 l fireflies1 gl[worms1 & w-o'-!-wisps1 h 9 !m "s sub/ance t is sl[ly *ang+ *emically1 & en]gy is releas$ 9 ! =m ( dim light z ! *ange takes place4 ,mo/ lum9\s pa9t is phosphoresc5t = ! same reason1--!re is a *emical *ange go+ on t releases en]gy 9 ! =m ( light4 ,:5 y p\r$ ! hydro*loric acid on ! z9c to make hydrog51 ! flask became w>m2 ! *emical *ange go+ on 9 ! flask releas$ heat en]gy4 ,,application #gf4 ,expla9 :y p\r+ cold wat] on cold quicklime makes ! slak$ lime t results boil+ hot2 :y a cat's eyes %9e 9 ! d>k2 :y a piece ( c>bon & a piece ( z9c plac$ 9 a solution ( sal ammoniac w make electricity run ?r\gh ! wire t connects !m2 :y fire is hot4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dha4 ,a bak+ potato sometimes bur/s 9 ! ov54 #dhb4 ,turp5t9e is us$ 9 mix+ pa9t4 #dhc4 ,sodium is a metal2 *lor9e is a poison\s gas2 yet salt1 :i* is made up ( ^! two1 is a h>mless food4 #dhd4 ,:5 bricklay]s mix wat] ) cem5t & lime1 ! result+ mort> boils & /eams4 #dhe4 ,gre5 plants w n gr[ 9 ! d>k4 #dhf4 ,p>ts ( ! body are con/antly unit+ ) oxyg54 ,?is keeps ! body w>m4 #dhg4 ,wat] w n always put out a k]os5e fire4 #dhh4 ,delicately color$ fabrics %\ld be hung 9 ! %ade to dry4 #dhi4 ,a mat* gl[s :5 y rub x 9 ! d>k4 #dij4 ,c&y h>d5s :5 x cools4 ,,section #eb4 ,explosions4 ,:at makes a gun %oot8 ,:at makes an automobile g8 ,usually we ?9k ( explosions z h>mful1 & !y (t5 are1 ( c\rse4 ,yet )\t !m we c\ld no long] run automobiles2 gasol9e laun*es w\ld /op at once2 motorcycles w\ld no long] run2 gasol9e eng9es = pump+ wat] or runn+ ma*9]y w\ld n be ( any use2 & all aviation w\ld imm$iately cease4 ,tunnel+ ?r\gh m\nta9s1 build+ roads 9 rocky places1 tak+ up tree /umps1 & prep>+ h>d gr\nd = crops w\ld all be made v mu* m difficult4 ,w> w\ld h to be c>ri$ on mu* z x 0 dur+ ! ,middle ,ages2 soldi]s w\ld use spe>s & b[s & arr[s2 battle%ips w\ld be almo/ useless 9 attack+2 mod]n =ts w\ld be ( little value2 cannon1 guns1 rifles1 h[itz]s1 mort>s1 & revolv]s w\ld all be s mu* junk4 ,illu/ration3 ,,fig4 #agi4 ,! explosion ( #ge p\nds ( dynamite4 ,a /ill f a motion-picture film4 ,illu/ration3 ,,fig4 #ahj4 ,diagram ( ! cyl9d] ( an eng9e4 ,! pi/on is driv5 =w>d by ! explosion ( ! gasol9e 9 ! cyl9d]4 ,,:at ,,makes ,,an ,,automobile ,,g4 ,9 all ! above cases ! explosions are caus$ by *emical action4 ,:5 gasol9e mix$ ) air is spray$ into ! cyl9d] ( an automobile1 an electric sp>k makes ! gasol9e comb9e ) ! oxyg5 ( ! air2 ! gasol9e sudd5ly burns & *anges to /eam & c>bon dioxid4 ,z y already "k1 :5 a liquid l gasol9e turns to gases su* z /eam & c>bon dioxid1 ! gases take mu* m room4 ,b t is n all t happ5s4 ,mu* heat is releas$ by ! burn+ ( ! gasol9e spray1 & heat causes expansion4 ,s ! gases =m$ by ! burn+ gasol9e are /ill fur!r exp&$ by ! heat releas$ by ! burn+4 ,!re=e !y ne$ a great deal m room2 b !y are %ut up 9 a small place 9 ! top ( a cyl9d]4 ,! only ?+ to hold !m up 9 ?is small space1 h[ev]1 is a pi/on 7,fig4 #ahj71 & ! sudd5ly exp&+ gases %ove ?is pi/on d[n & escape4 ,! pi/on is atta*$ to ! drive :eel ( ! automobile1 & :5 ! pi/on is pu%$ d[n x gives ! automobile a pu% =w>d4 ,if x 7 n = ! expansion ( a gas 9 ! cyl9d]1 ?is gas be+ conf9$ to a small space1 ! pi/on w\ld n be pu%$ d[n4 ,an explosion is simply ! sudd5 pu%+ ( a conf9$ gas exp&+ on its way to fre$om4 ,! gasol9e vapor & air 7 ! conf9$ gas4 ,_! *emical comb9+ made !m exp&2 by pu%+ ! pi/on out ( its way ! newly =m$ gas sudd5ly fre$ itself4 ,?is 0 an explosion1 & x gave ! automobile "o =w>d pu%4 ,b ! automobile eng9e is s arrang$ t ! pi/on goes up into ! cyl9d] aga91 & is pull$ d[n aga91 draw+ a spray ( gasol9e & air into ! cyl9d] aft] x4 ,!n x goes up a second "t1 an electric sp>k explodes ! gasol9e1 ! pi/on is =c$ d[n viol5tly once m1 & s x goes on4 ,!re are sev]al cyl9d]s1 ( c\rse1 & ! explosions take place )9 !m "o aft] ! o!r s z to keep ! automobile go+ /eadily4 ,,h[ ,a ,,gun ,,%oots4 ,pull+ a trigg] makes a gun %oot by caus+ an explosion4 ,!re is a spr+ on ! hamm] ( a gun4 ,?is drives ! hamm] d[n sudd5ly :5 y release ! spr+ by pull+ ! trigg]4 ,! hamm] j>s ! *emicals 9 ! cap & causes !m to explode4 ,! heat & flame !n cause ! oxyg5 9 ! gunp[d] to comb9e ) "s ( ! o!r elem5ts 9 ! p[d] to make a gas4 ,! gas requires m room ?an ! p[d] & is fur!r exp&$ by ! heat releas$ by ! *emical *ange4 ,! exp&+ gas frees itself by pu%+ ! bullet out ( its way4 ,! bullet gets su* a pu% ?r\gh ! explod+ ( ! gunp[d] t x may fly to a m>k & pi]ce x4 ,illu/ration3 ,,fig4 #aha4 ,! mo/ p[]ful explosions on e>? occur 9 connection ) volcanic activity4 ,! photograph %[s ,mt4 ,lass51 ,cali=nia1 ! only active volcano 9 ! ,unit$ ,/ates4 ,!re is a slight explosion ev5 :5 y %oot an air gun4 ,fir/ y compress "s air 9 ! upp] "p ( ! b>rel ( ! air gun2 !n y sudd5ly release x4 ,! only ?+ 9 ! way ( ! exp&+ air is ! bullet2 s ! air pu%es ?is out 9 front ( x4 ,9 ,exp]im5t #cf1 :]e y /opp]$ a te/ tube conta9+ a little wat] & !n held ! tube ov] a flame until ! cork flew out1 y 7 caus+ an explosion4 ,z ! wat] *ang$ to /eam1 ! /eam 0 an exp&+ gas4 ,x 0 at fir/ conf9$ to ! te/ tube by ! cork4 ,!n !re 0 an explosion2 ! gas fre$ itself by bl[+ out ! cork4 ,/eam boil]s h safety valves to prev5t explosions4 ,^! are valves s arrang$ t :5 ! /eam exp&s & presses h>d en\gh to endang] ! boil]1 ! /eam w op5 ! valves & escape in/ead ( bur/+ ! boil] to get free4 ,,explosives4 ,dynamite1 gunp[d]1 & mo/ explosives are mixtures ( solids or liquids t w comb9e easily & w =m gases t exp& greatly z a result ( ! comb9ation4 ,"o ( ! ess5tials 9 explosives is "s comp\nd ( oxyg5 7su* z ! manganese dioxid or potassium *lorate y us$ to make oxyg5 9 ,exp]im5t #ic7 :i* w easily set its oxyg5 free4 ,?is oxyg5 comb9es v swiftly ) some?+ else 9 ! explosive1 releas+ heat & =m+ a gas t takes mu* m room4 ,9 its ef=t to free itself1 ?is exp&+ gas w bla/ rocks out ( ! way1 %oot cannon balls1 or d any simil> "w4 ,b if gunp[d] does n h to pu% any?+ ( mu* importance out ( its way to exp&1 !re is no explosion4 ,t is :y a firecrack] m]ely fizzes :5 y break x 9 two & light ! p[d]4 ,! c>dbo>d no long] conf9es ! exp&+ gas2 s !re is no?+ to bur/ or to pu% viol5tly out ( ! way4 ,useful explosions are g5]ally caus$ by a *emical action :i* sudd5ly releases a great deal ( heat & comb9es solid ?+s into exp&+ gases4 ,b ! bur/+ ( a /eam boil]1 or ! bl[ out ( an automobile tire1 or ! bur/+ ( a potato 9 ! ov51 al?\gh n caus$ by *emical action1 /ill are real explosions4 ,an explosion is ! sudd5 release ( a conf9$ gas4 ,,application #gg4 ,expla9 h[ gasol9e makes a motorcycle g1 & :y x goes pop1 pop1 pop4 ,expla9 :y a pap] bag w bur/ ) a bang1 :5 y bl[ x up & !n clap x betwe5 y\r h&s2 :y a ,f\r?-(-,july torp$o goes (f :5 y ?r[ x on ! pavem5t4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #dia4 ,! eng9e ( an automobile is cool$ by ! wat] t passes ov] x f ! radiator4 #dib4 ,:5 y light a firecrack]1 ! flame travels d[n ! wick until x rea*es ! gunp[d]1 & !n ! firecrack] bur/s ) a bang4 #dic4 ,if y light a small pile ( gunp[d] 9 ! op51 z y d :5 y make a squib by break+ ! firecrack] 9 two1 y m]ely h a blaze4 #did4 ,air-fill$ tires make bicycles ride mu* m ev5ly ?an solid tires w\ld4 #die4 ,:5 clay has once be5 bak$ into brick1 y c nev] *ange x back to clay4 #dif4 ,a photographic negative turns black all ov] if x is expos$ to ! light be=e x is fix$4 #dig4 ,! outside ( a w9d[ %ade fades4 #dih4 ,a vacuum electric lamp globe feels hot in/antly :5 turn$ on1 b if turn$ (f aga9 at once1 x imm$iately feels cold4 #dii4 ,coal gas is made by heat+ coal v hot 9 an air-tight *amb]4 #ejj4 ,:ite /raw turns yell[ :5 x is long expos$ to ! sunlight4 ,,*apt] ,,elev5 ,,solution ,,& ,,*emical ,,action ,,section #ec4 ,*emical *ange help$ by solution4 ,:y does iron h to get wet to ru/8 ,is x good to dr9k wat] ) y\r meals8 ,:5 iron ru/s1 x is really sl[ly burn+ 7comb9+ ) oxyg574 ,if y\r h\se is on fire1 y ?r[ wat] on x to /op ! burn+4 ,yet if y ?r[ wat] on iron x ru/s1 or burns1 bett] ?an if y leave x dry4 ,:at d y suppose is ! reason = ?is8 ,! answ] is n difficult4 ,y "k p]fectly well t iron does n burn easily2 we c\ld n make fire grates & /oves out ( iron if x did4 ,b :5 iron is wet1 a little ( x dissolves 9 ! wat] t wets x4 ,!re is also a little oxyg5 dissolv$ 9 ! wat]1 z we "k f ! fact t fi% c brea! "u ! wat]4 ,?is dissolv$ oxyg5 c easily comb9e ) ! dissolv$ iron2 ! solution helps ! *emical *ange to take place4 ,! *emical *ange t results is oxidation1--! iron comb9+ ) oxyg51--:i* is a sl[ k9d ( burn+2 & 9 iron ?is is usually call$ ru/+4#aj ,b :5 we p\r wat] on burn+ wood1 ! wood /ops burn+1 = !re is n ne>ly en\gh oxyg5 dissolv$ 9 wat] to comb9e rapidly ) burn+ wood2 & ! wat] %uts (f ! outside air f burn+ wood & !re=e puts ! fire out4 ,footnote #aj3 ,! ru/+ ( iron is n q z simple z ?is1 z x probably und]goes two or ?ree *anges be=e f9ally comb9+ ) oxyg54 ,b ! solution helps all ^! *anges4 ,ano!r *emical *ange1 greatly help$ by solution1 is ! comb9+ ( ! two ?+s t bak+ p[d] is made (1 & ! sett+ free ( ! c>bon dioxid 7,,co#b7 t is 9 "o ( !m4 ,try ?is exp]im5t3 ,,exp]im5t #ajd4 ,put half a teaspoonful ( bak+ p[d] 9 ! bottom ( a cup & add a little wat]4 ,:at happ5s8 ,! *emical action :i* takes place 9 ! bak+ p[d] & releases ! gas 9 bubbles--! gas is c>bon dioxid 7,,co#b7--w n take place :ile ! bak+ p[d] is dry2 b :5 x is dissolv$1 ! *emical *ange takes place 9 ! solution4 ,if y ate y\r food entirely dry1 y w\ld h a h>d "t dige/+ x2 & ?is w\ld be = ! same reason t bak+ p[d] w n "w )\t wat]4 ,p]haps y c dr9k too mu* wat] ) a meal & dilute ! dige/ive juices too mu*2 c]ta9ly y %\ld n use wat] to wa% d[n y\r food & take ! place ( ! saliva1 = ! saliva is important 9 ! dige/ion ( />*4 ,b y ne$ also p>tly to dissolve ! food to h x dige/ well4 ,crack]s & milk are usually m easily dige/$ ?an are pla9 crack]s1 = ! milk p>tly dissolves ! crack]s1 & dr9k+ "o or two glasses ( wat] ) a meal ha/5s ! dige/ion ( ! food4 ,,application #gh4 ,expla9 :y pa9t pres]ves wood2 :y iron w ru/ m quickly 9 a wet place ?an x w ei!r "u wat] or 9 a dry place2 :y silv] salts mu/ be dissolv$ 9 ord] to plate a spoon by electricity4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #eja4 ,!re is dew on ! grass e>ly 9 ! morn+4 #ejb4 ,cold cream makes y\r h&s & face s(t4 #ejc4 ,gl[worms & fireflies c be se5 on ! d>ke/ nights4 #ejd4 ,a lake looks gray on a cl\dy day & blue on a cle> day4 #eje4 ,dri$ fruit w keep mu* long] ?an fre% fruit4 #ejf4 ,if y scrat* a v>ni%$ surface1 y c rub ! scrat* out completely by us+ a clo? wet ) alcohol4 #ejg4 ,soda is usually dissolv$ 9 a little wat] be=e x is add$ to a s\r-milk batt]4 #ejh4 ,iron ru/s :5 x gets wet4 #eji4 ,p]oxide is usually kept 9 br[n bottles4 #eaj4 ,dry lye may be kept 9 t9 cans1 b if ! lye is moi/5$ x w eat ! c4 ,,section #ed4 ,acids4 ,:y are lemons s\r8 ,h[ d acids act8 ,"s acids are v p[]ful4 ,!re is "o1 call$ hydr(luoric acid1 t w eat ?r\gh glass & has to be kept 9 wax bottles2 & all acids t5d to eat or corrode metals4 ,y saw :at hydro*loric acid did to ! z9c %av+s :5 y want$ to make a balloon2 or1 to be m accurate1 y saw :at ! z9c %av+s did to ! acid1 = ! hydrog5 gas t bubbl$ (f 0 driv5 out ( ! acid by ! z9c4 ,!n ! z9c comb9$ ) ! re/ ( ! acid to =m :at *emi/s call a salt4 ,if we 7 to let ! s(t metal1 sodium1 act on hydro*loric acid1 we %\ld get hydrog5 also2 b ! salt t =m$ w\ld be regul> table salt 7,na,cl74 ,y _c d ?is exp]im5t1 h[ev]1 z ! sodium does its "w s viol5tly t x is dang]\s4 ,,exp]im5t #aje4 ,to be done by ! tea*] be=e ! class4 ,if acid spatt]s on any "o's sk9 or clo!s1 wa% x ( imm$iately ) ammonia or a /rong soda solution4 ,drop a little c&le grease on a piece ( copp] ab\t #c_/d in* wide & #b or #c in*es long4 ,9 ! flame ( a ,buns5 burn]1 g5tly heat ! end ( ! copp] t has ! c&le grease 7p>aff97 on x1 s t ! p>aff9 w spread out all ov] ! end4 ,let x h>d54 ,) a nail1 draw a design 9 ! p>aff9 on ! copp]1 scrat*+ ?r\gh ! ?9 coat ( p>aff9 to ! copp] bel[4 ,p\r a c\ple ( drops ( conc5trat$ nitric acid on ! p>aff9-cov]$ end ( ! piece ( copp]1 & spread ! acid ) a mat* s t x c get d[n into ! scrat*es4 ,let x /& by an op5 w9d[ = #e or #aj m9utes4 ,d n inhale ! br[n fumes t are giv5 (f4 ,!y are h>mless 9 small am\nts1 b if brea!d directly !y are v irritat+4 ,n[ wa% (f ! acid by hold+ ! copp] "u ! hydrant1 & scrape (f ! p>aff94 ,illu/ration3 ,,fig4 #ahb4 ,et*+ copp] ) acid4 ,! nitric acid did to ! copp] 9 ?is exp]im5t exactly :at ! hydro*loric acid did to ! z9c %av+s :5 y made ! toy balloon4 ,! copp] drove ! hydrog5 out ( ! nitric acid & incid5tally broke d[n "s ( ! nitric acid to make ! br[n gas1 & !n ! copp] jo9$ ! re/ ( ! nitric acid to make a salt call$ copp] nitrate4 ,?is salt is gre51 & x dissolves 9 wat]4 ,:5 y wa%$ ! copp]1 ! gre5 salt 0 wa%$ away & a d5t rema9$ 9 ! copp] :]e ! copp] salt _h be54 ,"h is a m practical exp]im5t %[+ ! action ( acid on metal3 ,,exp]im5t #ajf4 ,use two knives1 "o ( bright /eel & ! o!r a silv]-plat$ "o4 ,if ! /eel knife is n bright1 sc\r x until x is4 ,drop a little lemon juice on ea* knife & let x /& = a few m9utes1 :ile ! tea*] does ! next exp]im5t4 ,!n r9se bo? knives & exam9e !m4 ,:at has ! lemon juice done to ! silv] knife8 to ! /eel "o8 ,! lemon juice acts 9 ?is way because x is acid4 ,acids act on ! ta/e n]ves 9 ! tongue & give ! ta/e ( s\rness2 ev]y?+ s\r is an acid4 ,! black /uff =m$ on ! /eel knife by ! lemon juice is an iron salt4 ,! iron 9 ! knife drove ! hydrog5 out ( ! lemon juice1 b !re 0 n en\gh = y to see x com+ (f2 !n ! iron comb9$ ) ! re/ ( ! lemon juice to =m an iron salt4 ,:5ev] an acid acts on a metal1 ! metal drives (f ! hydrog5 & =ms a salt4 ,! salt is n always good to eat2 = in/ance1 ! salt t t9 =ms ) acids is poison\s4 ,,action ,,( ,,acids ,,on ,,o!r ,,sub/ances4 ,acids d n act on metals only1 h[ev]4 ,wat* ! next exp]im5t to see :at a /rong acid w d to clo?4 ,,exp]im5t #ajg4 ,to be done by ! tea*]4 ,put a drop ( conc5trat$ nitric or sulfuric acid on a piece ( color$ wool clo?1 or on a piece ( color$ silk4 ,let x /& = a few m9utes1 !n r9se x ?or\ghly4 ,te/ ! clo? :]e ! acid has be5 to see :e!r or n x is z /rong z ! re/ ( ! clo?4 ,h[ has ! acid affect$ ! color8 ,illu/ration3 ,,fig4 #ahc4 ,/rong acids w eat holes l ?is 9 clo?4 ,,action ,,( ,,acids ,,on ,,! ,,n]ves ,,( ,,ta/e4 ,acids act on ! ta/e n]ves 9 ! tongue & give ! ta/e ( s\rness2 ev]y?+ s\r is an acid4 ,lemon juice1 s\r milk1 & s\r fruits are all too weak acids to injure clo!s or sk91 b _! s\r ta/e is a result ( ! acid 9 !m act+ on ! n]ves ( ta/e4 ,,application #gi4 ,a girl want$ to make lemonade4 ,%e did n "k :i* ( two knives to use1 a /eel-blad$ "o or a silv]-plat$ "o4 ,:i* %\ld %e h us$8 ,,application #hj4 ,a woman 0 go+ to put up "s tomatoes4 ,%e ne$$ some?+ l>ge to cook !m 94 ,%e _h a %9y new t9 di% pan1 an old] enamelw>e di% pan1 a galvaniz$ iron wat] pail1 & an old-fa%ion$ copp] kettle4 ,:i* w\ld h be5 be/ = h] to use8 ,make a li/ ( z _m acids z y c ?9k (4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #eaa4 ,sug> dissolves readily 9 hot c(fee4 #eab4 ,! sug> disappe>s1 yet ! c(fee flavor rema9s & s does ! sweetness ( ! sug>4 #eac4 ,a t9 spoon left ov]night 9 apple sauce becomes black4 #ead4 ,if "o's clo!s are on fire1 roll+ ov] on ! gr\nd is bett] ?an runn+4 #eae4 ,lemon juice blea*es /raw hats4 #eaf4 ,w-o'-!-wisps gl[ at night1 deceiv+ travel]s by _! resemblance to mov+ lant]ns4 #eag4 ,tomatoes %\ld nev] be left 9 a t9 c aft] x has be5 op5$4 #eah4 ,boil$ milk ta/es diff]5t f ord9>y milk4 #eai4 ,y\r h&s become v cold aft] y h wa%$ ?+s 9 gasol9e4 #ebj4 ,wood decays m quickly :5 wet ?an :5 dry4 ,,section #ee4 ,bases4 ,:y does /rong soap make y\r face /+8 ,h[ is soap made8 ,conta9s no free alkali1 ,w n injure ! mo/ delicate ( fabrics1 #ii-dd_/ajj pure1--su* phrases z ^! are us$ 9 adv]tis+ soaps4 ,:at is meant by #ii-dd_/ajj pure8 ,:at is free alkali8 ,:y %\ld any soap injure fabrics8 ,:at makes a soap /rong8 ,! answ] to all ^! que/ions is t !re are "s sub/ances call$ bases1 :i* are ! opposites ( acids1 & "s ( :i* are z p[]ful z acids4 ,lye1 ammonia1 cau/ic soda1 & bak+ & wa%+ soda are common bases4 ,! /rong bases1 l lye & cau/ic soda1 are also call$ alkalies4 ,if y want to see :at a /rong base--an alkali--w d to ! mo/ delicate ( fabrics1 & to fabrics t are n s delicate1 = t matt]1 try ! foll[+ exp]im5t3 ,,exp]im5t #ajh4 ,to be done by ! tea*]4 ,if y get any alkali on y\r sk9 or clo!s1 wa% x (f imm$iately ) v9eg> or lemon juice4 ,put half a teaspoonful ( lye & a qu>t] ( a cup ( wat] into a beak]1 a small pan1 or an evaporat+ di%4 ,br+ x to a g5tle boil4 ,drop a small piece ( wool5 clo? & a small piece ( silk clo? into x & let !m boil g5tly = a c\ple ( m9utes4 ,:at happ5s to !m8 ,try a piece ( pla9 cotton clo?1 & !n a piece ( clo? t is mix$ wool & cotton or mix$ silk & cotton4 ,:at happ5s to !m8 ,?is is a v good te/ to det]m9e :e!r any goods y buy are pure silk or wool1 or :e!r !re is a cotton ?read mix$ ) !m4 ,drop "o end ( a long hair into ! hot lye solution4 ,:at happ5s to x8 ,drop a speck ( meat or a piece ( f+] nail into x4 ,f ?is exp]im5t y c readily see :y lye w burn y\r sk9 & ru9 y\r clo!s4 ,y c also see h[ x s(t5s ! food t /icks to ! bottom ( ! cook+ pan & makes ! pan easy to clean4 ,lye is "o ( ! /ronge/ bases or alkalies 9 ! _w4 ,illu/ration3 ,,fig4 #ahd4 ,! lye has *ang$ ! wool clo? to a jelly4 ,,h[ ,,soap ,,is ,,made4 ,:5 lye & grease are boil$ toge!r1 !y =m soap4 ,y _c v well make soap 9 ! laboratory n[1 z ! measurem5ts mu/ be exact & y ne$ a good deal ( /rong lye to make x 9 a quantity l>ge en\gh to use4 ,b ! fact t soap is made ) oil1 fat1 or grease boil$ ) lye1 or cau/ic soda1 :i* is almo/ ! same ?+1 %[s :y a soap mu/ be #ii-dd_/ajj pure1 or some?+ l t1 if x is n to injure ! mo/ delicate fabric4 ,if a little too mu* lye is us$ !re w be free alkali 9 ! soap1 & x w make y\r h&s h>% & sore & spoil ! clo!s y are wa%+4 ,a pure soap is "o ) no free alkali 9 x4 ,a /rong soap is "o t does h "s free alkali 9 x2 !re is a little too mu* lye = ! oil or fat1 s "s lye is left uncomb9$ :5 ! soap is made4 ,?is free alkali cleans ?+s well1 b x injures h&s & clo!s4 ,:5 ! dra9pipe ( a kit*5 s9k is /opp$ up1 y c (t5 cle> x by spr9kl+ lye d[n x1 & !n add+ boil+ wat]4 ,if y ev] d ?is1 /& well back s t no lye w spatt] into y\r face2 x sputt]s :5 ! boil+ wat] /rikes x4 ,! grease 9 ! dra9pipe comb9es ) ! lye :5 ! hot wat] comes d[n2 !n ! soap t is =m$ is c>ri$ d[n ! pipe1 p>tly dissolv$ by ! hot wat]4 ,:5 y sponge a grease spot ) ammonia1 ! same sort ( *emical action takes place4 ,! ammonia is a base2 x comb9es ) ! grease to =m soap1 & ?is soap r9ses out ( ! clo?4 ,,! ,,litmus ,,te/4 ,to tell :at ?+s are bases & :at are acids1 a piece ( pap] dy$ ) litmus is ord9>ily us$4 ,litmus is made f a plant 7li*574 ,?is pap] is call$ litmus pap]4 ,try ! foll[+ exp]im5t ) litmus pap]3 ,,exp]im5t #aji4 ,p\r a few drops ( ammonia1 a base1 into a cup4 ,into ano!r cup p\r a few drops ( v9eg>1 an acid4 ,dip y\r litmus pap] fir/ into "o1 !n into ! o!r1 & !n back into ! fir/4 ,:at color does ! v9eg> turn x8 ! ammonia8 ,try lemon juice2 dilut$ hydro*loric acid2 a v dilute lye solution4 ,?is is call$ ! litmus te/4 ,all ord9>y acids1 if n too /rong1 w turn litmus p9k4 ,all bases or alkalies w turn x blue4 ,if x is already p9k :5 y put x into an acid1 x w /ay p9k1 ( c\rse2 if x is already blue :5 y put x into a base1 x w /ay blue4 ,b if y put a piece ( litmus pap] into some?+ t is nei!r an acid nor a base1 l sug> or salt1 x w /ill /ay ! same color4 ,s1 to te/ = a base1 use a piece ( litmus pap] t is p9k & see if x turns blue1 or if y want to te/ = an acid1 use blue litmus pap]4 ,d ?is exp]im5t3 ,,exp]im5t #aaj4 ,) p9k & blue litmus pap]1 te/ ! diff]5t sub/ances nam$ bel[ to see :i* are acids & :i* are bases4 ,make a li/ ( all ! acids & ano!r li/ = all ! bases4 ,d n put d[n any?+ t is nei!r acid or base4 ,y _c be sure a ?+ is an acid unless x turns blue litmus p9k4 ,a piece ( p9k litmus w\ld /ay p9k 9 an acid1 b x w\ld also /ay p9k 9 ?+s t 7 nei!r acid nor base1 l salt or wat]4 ,9 ! same way y _c be sure a ?+ is a base unless x turns p9k litmus blue4 ,"h is a li/ ( ?+s to try3 #a1 sug>2 #b1 orange2 #c1 dilute sulfuric acid2 #d1 bak+ soda 9 wat]2 #e1 alum 9 wat]2 #f1 wa%+ soda 9 wat]2 #g1 ammonia2 #h1 dilute lye2 #i1 lemon juice2 #aj1 v9eg>2 #aa1 wa%+ p[d] 9 wat]2 #ab1 s\r milk2 #ac1 corn/>* 9 wat]2 #ad1 wet kit*5 soap2 #ae1 oil2 #af1 salt 9 wat]4 ,y may h to make ! orange & s\r milk te/ at home4 ,y may take two pieces ( litmus pap] home ) y & te/ any?+ else t y may c>e to4 ,if y h a g>d51 try ! soil 9 x4 ,if x is acid x ne$s lime4 ,,application #ha4 ,a boy spill$ "s greasy s\p on 8 be/ d>k blue coat4 ,:i* ( ! foll[+ me?ods w\ld h s]v$ to clean ! coat8 to sponge x 7a7 ) cold wat]2 7b7 ) wat] 7hot7 & ammonia2 7c7 ) hot wat] & v9eg>2 7d7 ) conc5trat$ nitric acid2 to spr9kle lye on ! spot & p\r boil+ wat] ov] x4 ,,application #hb4 ,a woman scor*$ ! oatmeal %e 0 cook+ = breakfa/4 ,:5 %e want$ to wa% ! pan1 %e f\nd t ! black5$ c]eal /uck fa/ to ! bottom4 ,:i* ( ! foll[+ ?+s w\ld h s]v$ be/ to loos5 ! burn$ oatmeal f ! pan3 lye & hot wat]1 ammonia1 v9eg>1 salt wat]1 lemon juice8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #eba4 ,aft] clo!s h be5 wa%$ ) wa%+ soda or /rong soap1 !y %\ld be ?or\ghly r9s$4 ,o!rwise !y w be badly eat5 z !y dry4 #ebb4 ,c>bon w burn2 oxyg5 w support combu/ion2 yet c>bon dioxid 7,,co#b71 :i* is made ( bo? ^! elem5ts1 w nei!r burn nor support combu/ion4 #ebc4 ,y c clean silv] by putt+ x 9 hot soda solution 9 contact ) alum9um4 #ebd4 ,:5 y /ub y\r toe :ile walk+1 y t5d to fall =w>d4 #ebe4 ,electric lamps gl[ :5 y turn on ! swit*4 #ebf4 ,if y use mu* ammonia 9 wa%+ clo!s or clean+1 y\r h&s become h>% & dry4 #ebg4 ,if a p]son swall[s lye or cau/ic soda1 he %\ld imm$iately dr9k z mu* vegetable oil or animal oil z possible4 #ebh4 ,wat] is made ( hydrog5 & oxyg52 air is made ( nitrog5 & oxyg52 yet :ile ?+s w n burn 9 wat]1 !y w burn easily 9 air4 #ebi4 ,! backs ( books t h be5 kept 9 cases = sev]al ye>s are n z bright color$ z ! side cov]s4 #ecj4 ,if y try to burn a book or magaz9e 9 a grate1 only ! out] pages & edges burn4 ,,section #ef4 ,neutralization4 ,:5 y put soda 9 v9eg>1 :at makes ! v9eg> less s\r8 ,:5 we use s\r milk = cook+1 :y does ! food n ta/e s\r8 ,"o ( ! mo/ int]e/+ & important facts ab\t acids & bases is t if !y are put toge!r 9 ! "r proportions !y turn to salt & wat]4 ,/rong hydro*loric acid 7,h,cl71 = in/ance1 w attack ! sk9 & clo!s1 z y "k2 if y %\ld dr9k x1 x w\ld kill y4 ,cau/ic soda 7,na,o,h71 a k9d ( lye1 is su* a /rong alkali t x w\ld dissolve ! sk9 ( y\r m\? 9 ! way t lye dissolv$ hair 9 ,exp]im5t #ajh4 ,yet if y put ^! two /rongly poison\s *emicals toge!r1 !y promptly turn to ord9>y table salt 7,na,cl7 & wat] 7,h#b,o74 ,or1 z ! *emi/s write x3 ,na,o,h,h,cl - ,na,cl,h#b,o4 ,y c make ?is happ5 y\rself 9 ! foll[+ exp]im5t1 us+ ! acid & base dilute en\gh s t !y w n hurt y3 ,,exp]im5t #aaa4 ,al?\gh /rong hydro*loric acid & /rong cau/ic soda are dang]\s1 if !y are dilut$ ) en\gh wat] !y are p]fectly h>mless4 ,y w f9d two bottles1 "o label$ cau/ic soda 7,na,o,h7 dilut$ = ta/+1 & ! o!r label$ hydro*loric acid 7,h,cl7 dilut$ = ta/+4 ,f "o bottle take a little 9 ! m$ic9e dropp] & let a drop fall on y\r tongue4 ,ta/e ! cont5ts ( ! o!r bottle 9 ! same way4 ,x is n usually safe to ta/e ?+s 9 ! laboratory4 ,ta/e only ^? ?+s :i* are m>k$ = ta/+4 ,n[ put a teaspoonful ( ! same hydro*loric acid into a clean evaporat+ di%4 ,lay a piece ( litmus pap] 9 ! bottom ( ! di%4 ,) a m$ic9e dropp] gradually add ! dilute cau/ic soda 7,na,o,h71 /irr+ z y add x4 ,wat* ! litmus pap]4 ,:5 ! litmus pap] beg9s to turn blue1 add ! dilute cau/ic soda drop by drop until ! litmus pap] /ays blue :5 y /ir ! mixture4 ,n[ add a drop or two m ( ! acid until ! litmus turns p9k aga94 ,ta/e ! mixture4 ,put ! evaporat+ di% on ! wire gauze ov] a ,buns5 burn]1 & br+ ! liquid to a boil4 ,boil x g5tly until x beg9s to sputt]4 ,!n take ! ,buns5 burn] 9 y\r h& & hold x "u ! di% = a c\ple ( seconds2 remove x = a few seconds1 & !n aga9 hold x "u ! di% = a c\ple ( seconds2 remove x once m1 & keep ?is up until ! wat] has all evaporat$ & left dry :ite cry/als & p[d] 9 ! bottom ( ! di%4 ,z soon z ! di% is cool1 ta/e ! cry/als & p[d]4 ,:at are !y8 ,is salt an acid or a base8 ,:5ev] y put acids & bases toge!r1 y get "s k9d ( salt & wat]4 ,?us ! *lor9e 7,cl7 ( ! hydro*loric acid 7,h,cl7 comb9es ) ! sodium 7,na7 ( cau/ic soda 7,na,o,h7 to =m ord9>y table salt1 sodium *loride 7,na,cl71 :ile ! hydrog5 7,h7 ( ! hydro*loric acid 7,h,cl7 comb9es ) ! oxyg5 & hydrog5 7,,oh7 ( ! cau/ic soda 7,na,o,h7 to =m wat] 7,h#b,o74 ,*emi/s write ?is z foll[s3 ,na,o,h,h,cl - ,na,cl,h#b,o4 ,,:y ,,s\r ,,milk ,,pancakes ,,are ,,n ,,s\r4 ,x is because bases neutralize acids t y put bak+ soda ) s\r milk :5 y make s\r milk pancakes or muff9s4 ,! soda is a weak base4 ,! s\r milk is a weak acid4 ,! soda neutralizes ! acid1 *ang+ x into a k9d ( salt & pla9 wat]4 ,!re=e ! s\r milk pancakes or muff9s d n ta/e s\r4 ,9 ! same way a little soda keeps tomatoes f curdl+ ! milk :5 x is add$ to make cream ( tomato s\p4 ,x is ! acid 9 ! tomatoes t curdles milk4 ,if y neutralize ! acid by add+ a base1 !re is no acid left to curdle ! milk2 ! acid & base turn to wat] & a k9d ( salt4 ,:5 y did an exp]im5t ) /rong acid1 y 7 advis$ to h "s ammonia at h& to wa% (f any acid t might get on y\r sk9 or clo!s4 ,! ammonia1 be+ a base1 w\ld imm$iately neutralize ! acid & !re=e keep x f do+ any damage4 ,lye also w\ld neutralize ! acid1 b if y us$ ! lea/ bit too mu*1 ! lye w\ld d z mu* h>m z ! acid4 ,t is :y y %\ld use a weak base1 l ammonia or bak+ soda or wa%+ soda1 to neutralize any acid t spills on y4 ,!n if y get too mu* on1 x w n d any h>m4 ,9 ! same way y 7 w>n$ to h v9eg> ne> at h& :ile y work$ ) lye4 ,/rong nitric acid also w\ld neutralize ! lye1 b if y happ5$ to use a drop too mu*1 ! acid w\ld be worse ?an ! lye4 ,v9eg>1 ( c\rse1 w\ld n hurt y1 no matt] h[ mu* y put on4 ,any acid w neutralize any base4 ,b x w\ld take a great deal ( a weak acid to neutralize a /rong base or alkali2 y w\ld h to use a great deal ( v9eg> to neutralize conc5trat$ lye4 ,9 ! same way x w\ld take a great deal ( a weak base to neutralize a /rong acid2 y w\ld h to use a l>ge am\nt ( bak+ soda or ammonia to neutralize conc5trat$ nitric acid4 ,,application #hc4 ,a woman 0 clean+ kettles ) lye4 ,h] little boy 0 play+ ne>1 & "s lye spla%$ on 8 h&4 ,%e look$ swiftly ar\nd & saw ! foll[+ ?+s3 soap1 oil1 lemon1 fl\r1 p]oxide1 ammonia1 iod9e1 bak+ soda1 ess5ce ( pepp]m9t4 ,:i* %\ld %e h put on ! boy's h&8 ,,application #hd4 ,a tea*] spill$ "s nitric acid on h] apron4 ,on ! %elf !re 73 hydro*loric acid1 v9eg>1 lye1 cau/ic soda1 bak+ soda1 ammonia1 salt1 alcohol1 k]os5e1 salad oil4 ,:i* %\ld %e h put on h] apron8 ,,application #he4 ,a boy _h s\r /oma*4 ,8 si/] said1 ,*ew "s gum4 ,8 aunt said1 ,dr9k hot wat] ) a little pepp]m9t 9 x4 ,8 "m told him to take a little bak+ soda 9 wat]4 ,8 bro!r said1 ,try "s hot lemonade4 ,:i* advice %\ld he h foll[$8 ,,application #hf4 ,two wom5 7 blea*+ a fad$ pair ( curta9s4 ,! ,javelle wat] :i* !y _h us$ 0 made ( blea*+ p[d] & wa%+ soda4 ,be=e hang+ ! curta9s out to dry1 "o ( !m said t %e 0 afraid ! ,javelle wat] w\ld become s /rong z ! wat] evaporat$ f ! curta9s t x w\ld eat ! curta9s4 ,!y decid$ !y _h bett] r9se !m out ) some?+ t w\ld c\nt]act ! soda & lime 9 ! ,javelle wat]1 & 9 ! laundry & pantry !y f\nd3 ammonia1 blue+1 />*1 wa%+ p[d]1 soap1 v9eg>1 & gasol9e4 ,:i* ( !m1 if any1 w\ld x h be5 well to put 9 ! r9s+ wat]8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #eca4 ,solid pieces ( wa%+ soda disappe> 9 hot wat]4 #ecb4 ,greasy clo!s put into hot wat] ) wa%+ soda become clean4 #ecc4 ,if y hang ^! clo!s up to dry )\t r9s+ !m1 ! soda w weak5 ! clo?4 #ecd4 ,lemon juice 9 ! r9s+ wat] w prev5t wa%+ soda f injur+ ! clo!s4 #ece4 ,if y hang !m 9 ! sun1 ! color w fade4 #ecf4 ,a piece ( soot bl[n aga9/ !m w /ick4 #ecg4 ,a drop ( oil t may spatt] aga9/ !m w spread4 #ech4 ,! clo!s w be easi] to iron if damp5$4 #eci4 ,! creases made 9 iron+ ! clo!s w reappe> ev5 if y flatt5 ! creases out ) y\r h&4 #edj4 ,aft] !y h be5 worn1 wa%$1 & iron$ a numb] ( times1 clo!s are ?9n] ?an !y 7 :5 !y 7 new4 ,,section #eg4 ,eff]vesc5ce4 ,:at makes bak+ p[d] bubble8 ,:at makes ! foam on soda wat]8 ,did y ev] make soda lemonade8 ,x is easy to make & is r good4 ,try mak+ x at home4 ,"h are ! directions3 ,,exp]im5t #aab4 ,make a glass ( ord9>y lemonade 7half a lemon1 #a-a_/b teaspoonfuls ( sug>2 fill ! glass ) wat]74 ,p\r half ( ?is lemonade into ano!r cup or glass4 ,into ! rema9+ half glass /ir half a teaspoonful ( soda4 ,dr9k x :ile x fizzes4 ,does x ta/e s\r8 ,:5 any?+ fizzes or bubbles up l ?is1 we say t x eff]vesces4 ,eff]vesc5ce is ! bubbl+ up ( a gas f a liquid4 ,! gas t bubbl$ up f y\r lemonade 0 c>bon dioxid 7,,co#b71 & ?is is ! gas t usually bubbles up out ( ?+s :5 !y eff]vesce4 ,:5 y make bread1 ! yea/ turns ! sug> into c>bon dioxid 7,,co#b7 & alcohol4 ,! c>bon dioxid tries to bubble up out ( ! d\gh1 & ! bubbles make little holes all ?r\gh ! d\gh4 ,?is makes ! bread light4 ,:5 bread rises1 x really is sl[ly eff]vesc+4 ,,h[ ,,soda ,,wat] ,,is ,,made4 ,c]ta9 firms make pure c>bon dioxid 7comm]cially kn[n z c>bonic acid gas7 & compress x 9 iron tanks4 ,^! iron tanks ( c>bon dioxid 7,,co#b7 are %ipp$ to soda-wat] f\nta9s & soda-bottl+ works4 ,"h ! compress$ c>bon dioxid is dissolv$ 9 wat] "u pressure1--?is is call$ *>g+ ! wat]4 ,:5 ! *>g$ wat] comes out ( ! faucet 9 ! soda f\nta9s1 or out ( ! sp\t ( a seltz] siphon1 or out ( a bottle ( soda pop1 ! c>bon dioxid t 0 dissolv$ 9 ! wat] "u pressure bubbles up & escapes1--! soda wat] eff]vesces4 ,sometimes !re is compress$ c>bon dioxid d[n 9 ! gr\nd4 ,?is dissolves 9 ! und]gr\nd wat]1 & :5 ! wat] bubbles up f ! gr\nd & ! pressure is releas$1 ! c>bon dioxid foams out ( ! wat]2 x eff]vesces l ! *>g$ wat] at a soda f\nta94 ,b ! mo/ useful & be/-kn[n eff]vesc5ce is ! k9d y got :5 y /irr$ ! bak+ soda 9 ! lemonade4 ,bak+ soda is made ( ! same elem5ts z cau/ic soda 7,na,o,h71 ) c>bon dioxid 7,,co#b7 comb9$ ) !m4 ,! =mula = bak+ soda c\ld be writt5 ,na,o,h,c,o#b1 b usually *emi/s put all ( ! ,o's toge!r at ! end & write x ,na,h,c,o#c4 ,:5ev] bak+ soda is mix$ ) any k9d ( acid1 ! cau/ic soda "p 7,na,o,h7 is us$ up 9 neutraliz+ ! acid4 ,?is leaves ! c>bon dioxid 7,,co#b7 "p free1 s t x bubbles (f & we h eff]vesc5ce4 ,bak+ soda mix$ ) an acid always eff]vesces4 ,t is :y s\r milk muff9s & pancakes are light z well z n s\r4 ,! eff]vesc+ c>bon dioxid makes bubbles all ?r\gh ! batt]1 :ile ! cau/ic soda 7,na,o,h7 9 ! bak+ soda neutralizes ! acid ( ! s\r milk4 ,illu/ration3 ,,fig4 #ahe4 ,mak+ a glass ( soda lemonade4 ,,eff]vesc5ce ,,g5]ally ,,due ,,to ,,! ,,free+ ,,( ,,c>bon ,,dioxid4 ,s9ce bak+ soda is s mu* us$ 9 ! home = neutraliz+ acids1 p sometimes get ! idea t :5ev] !re is neutralization !re is eff]vesc5ce4 ,( c\rse ?is is n true4 ,:5ev] y neutralize an acid ) bak+ soda or wa%+ soda1 ! c>bon dioxid 9 ! soda bubbles up & y h eff]vesc5ce4 ,b if y neutralize an acid ) ammonia1 lye1 or pla9 cau/ic soda1 !re is n a bit ( eff]vesc5ce4 ,ammonia1 lye1 & pla9 cau/ic soda h no c>bon dioxid 9 !m to bubble out4 ,bak+ p[d] is m]ely a mixture ( bak+ soda & dry acid 7cream ( t>t> or phosphates 9 ! bett] bak+ p[d]s1 alum 9 ! *eap ones74 ,^! dry acids _c act on ! soda until !y g into solution4 ,z long z ! bak+ p[d] rema9s dry 9 ! c1 !re is no eff]vesc5ce4 ,b :5 ! bak+ p[d] is /irr$ into ! moi/ biscuit d\gh or cake batt]1 ! bak+ p[d] dissolves2 s ! acid 9 x c act on ! bak+ soda & set free ! c>bon dioxid4 ,9 mo/ cases x is ! free+ ( c>bon dioxid t con/itutes eff]vesc5ce1 b ! free+ ( any gas f liquid is eff]vesc5ce4 ,:5 y made hydrog5 by p\r+ hydro*loric acid 7,h,cl7 on z9c %av+s1 ! acid eff]vesc$1--! hydrog5 gas 0 set free & x bubbl$ up4 ,/irr+ or %ak+ helps eff]vesc5ce1 j z x does cry/allization4 ,z ! little bubbles =m1 ! /irr+ or %ak+ br+s !m toge!r & lets !m jo9 to =m big bubbles t pass quickly up ?r\gh ! liquid4 ,t is :y soda pop w foam s mu* if y %ake x be=e y p\r x1 or if y /ir x 9 y\r glass4 ,,application #hg4 ,expla9 :y we d n neutralize ! acid 9 s\r milk g+]bread ) weak cau/ic soda in/ead ( ) bak+ soda2 :y soda wat] :i* is drawn ) consid]able =ce f ! f9e op5+ at a soda f\nta9 makes s mu* m foam ?an does ! same *>g$ wat] if x is drawn f a l>ge op5+1 f :i* x fl[s g5tly2 :y !re is always bak+ soda & dry acid 9 bak+ p[d]4 ,,application #hh4 ,a woman want$ to make g+]bread4 ,%e _h no bak+ p[d] & no s\r milk1 b %e _h sweet milk & all ! o!r articles necess>y = mak+ g+]bread4 ,%e _h also bak+ soda1 cau/ic soda1 lemons1 oranges1 vanilla1 salad oil1 v9eg>1 & lye4 ,0 !re any way 9 :i* %e might h made ! g+]bread light )\t spoil+ x8 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #eda4 ,h>ness is oil$ to keep x flexible4 #edb4 ,:5 y p\r nitric acid on copp] fil+s1 !re is a bubbl+ up ( gas4 #edc4 ,! flask or di% 9 :i* ! action takes place becomes v hot4 #edd4 ,! copp] disappe>s & a cle> gre5 solution is left4 #ede4 ,9 mak+ cream ( tomato s\p1 soda is add$ to ! tomatoes be=e ! milk is1 s t ! milk w n curdle ,h[ does ! soda prev5t curdl+8 #edf4 ,! soda makes ! s\p fro? up4 #edg4 ,a wagon squeaks :5 an axle ne$s greas+4 #edh4 ,seidlitz p[d]s are mix$ 9 only half a glass ( wat]4 #edi4 ,! "w ( develop+ photographs is all done ) a ruby light = illum9ation4 #eej4 ,coal slides =w>d (f ! %ovel into a furnace :5 y /op ! %ovel at ! furnace door4 ,,*apt] ,,twelve ,,analysis ,,section #eh4 ,analysis4 ,h[ c p tell :at ?+s are made (8 ,if x 7 n = *emical analysis1 mo/ ( ! big factories w\ld h to %ut d[n1 mu* ( our agricultural exp]im5tation w\ld /op1 ! ,pure ,food ,law w\ld be impossible to en=ce1 m9+ w\ld be p>alyz$1 & ! sci5ce ( *emi/ry w\ld almo/ vani%4 ,analysis is f9d+ out :at ?+s are made (4 ,9 ord] to make /eel f ore1 ! ore has to be analyz$2 & factories c\ld n run v well )\t /eel4 ,9 ord] to te/ soil1 to te/ c['s milk1 or to f9d ! food value ( diff]5t k9ds ( fe$1 analysis is ess5tial4 ,z to ! ,pure ,food ,law1 h[ c\ld ! gov]nm5t f9d out t a firm 0 us+ artificial color+ matt] or pres]vatives if !re 7 no way ( analyz+ ! food8 ,9 m9+1 ! ore mu/ be assay$2 t is1 x mu/ be analyz$ to %[ :at "p ( x is gold1 = in/ance1 & :at "p consi/s ( o!r m9]als4 ,also1 ! analysis mu/ %[ :at ^! sub/ances are1 s t !y c be treat$ prop]ly4 ,& ! sci5ce ( *emi/ry is l>gely ! sci5ce ( analyz+--f9d+ out :at ?+s are made ( & h[ !y w act on ea* o!r4 ,! subject ( *emical analysis is extremely important4 ,b 9 ?is c\rse x is impossible & unnecess>y = y to le>n to analyze ev]y?+2 ! ma9 ?+ is = y to "k :at analysis is & to h a g5]al notion ( h[ a *emi/ analyzes ?+s4 ,illu/ration3 ,,fig4 #ahf4 ,! plat9um loop us$ 9 mak+ ! borax bead te/4 ,:5 y te/$ a numb] ( sub/ances ) litmus pap] to f9d out :i* ( !m 7 acids1 y 7 really do+ "s "w 9 *emical analysis4 ,*emi/s actually use litmus pap] 9 ?is way to f9d out :e!r a sub/ance is an acid or a base4 ,,! ,,borax ,,bead ,,te/4 ,?is is ano!r *emical te/1 by :i* c]ta9 sub/ances c be recogniz$3 ,,exp]im5t #aac4 ,make a loop ( wire ab\t a qu>t] ( an in* across1 us+ light-weight plat9um wire 7ab\t ,no4 #cj74 ,seal ! /raight end ( ! wire into ! end ( a piece ( glass tub+ by melt+ ! end ( ! tube ar\nd ! wire4 ,hold ! loop ( wire 9 ! flame ( a ,buns5 burn] = a few seconds1 !n dip ! loop$ end 9 borax p[d]4 ,be c>eful n to get borax on ! upp] "p ( ! wire or on ! h&le4 ,"s ( ! borax w /ick to ! hot loop4 ,hold ?is 9 ! flame until x melts into a glassy bead 9 ! loop4 ,y may h to dip x into ! borax once or twice m to get a good-siz$ bead4 ,:5 ! bead is all glassy1 & :ile x is melt$1 t\* x lightly to "o small gra9 ( "o ( ! *emicals on ! jewel-mak+ plate4 ,?is jewel-mak+ plate is a plate ) six small heaps ( *emicals on x4 ,!y are3 manganese dioxid1 copp] sulfate1 cobalt *lorid1 nickel salts1 *rome alum1 & silv] nitrate4 ,put ! bead back into ! flame & let x melt until ! color ( ! *emical has run all ?r\gh x4 ,!n :ile x is /ill melt$1 %ake ! bead out ( ! loop on to a clean plate4 ,if x is d>k color$ & cl\dy1 try aga91 gett+ a /ill small] gra9 ( ! *emical4 ,y %\ld get a bead t is transp>5t1 b cle>ly color$1 l an em]ald1 topaz1 or sapphire4 ,repeat ) ea* ( ! six *emicals1 s t y h a set ( six diff]5t-color$ beads4 ,illu/ration3 ,,fig4 #ahg4 ,mak+ ! te/4 ,?is is a regul> *emical te/ = c]ta9 elem5ts :5 !y are comb9$ ) oxyg54 ,! cobalt w always *ange ! borax bead to ! blue y got2 ! *romium w make ! bead em]ald gre5 or1 9 c]ta9 k9ds ( flame1 ruby r$2 etc4 ,if y want$ to "k :e!r or n c]ta9 sub/ances conta9$ cobalt comb9$ ) oxyg51 y c\ld really f9d out by tak+ a gra9 on a borax bead & see+ if x turn$ blue4 ,,! ,,hydro*loric ,,acid ,,te/ ,,= ,,silv]4 ,! exp]im5t 9 :i* y te/$ ! action ( light 9 effect+ *emical *ange1 & 9 :i* y made a :ite p[d] or precipitate 9 a silv] nitrate solution by add+ hydro*loric acid 7page #cbg71 is a regul> *emical te/ to f9d out :e!r or n a ?+ has silv] 9 x4 ,if any silv] is dissolv$ 9 nitric acid1 y w get a precipitate 7p[d]7 :5 hydro*loric acid is add$4 ,make ! te/ 9 ! foll[+ exp]im5t3 ,,exp]im5t #aad4 ,use di/ill$ wat] all ?r\gh ?is exp]im5t if possible4 ,fir/ wa% two te/ tubes & an evaporat+ di% ?or\ghly1 r9s+ !m sev]al times4 ,into "o te/ tube p\r "s nitric acid dilut$ #a to #d4 ,heat ?is to boil+1 !n add a few drops ( hydro*loric acid dilut$ #a to #aj4 ,does any?+ happ58 ,p\r out ?is acid & r9se ! di% ?or\ghly4 ,n[ put a piece ( silv] or any?+ p>tly made ( silv] into ! bottom ( ! evaporat+ di%4 ,d n use any?+ = ! appe>ance ( :i* y c>e4 ,cov] ! silv] ) "s ( ! dilute nitric acid1 put ! di% ov] ! ,buns5 burn] on a wire gauze1 & br+ ! acid to a g5tle boil4 ,z soon z x boils1 take ! di% (f1 p\r "s clean1 cold wat] into x to /op ! action1 & p\r ! liquid (f into ! clean te/ tube4 ,add a few drops ( ! dilute hydro*loric acid to ! liquid 9 ! te/ tube4 ,:at happ5s8 ,:at does ?is %[ mu/ h be5 9 ! liquid8 ,y c detect v small am\nts ( silv] 9 a liquid by ?is te/4 ,x is a regul> te/ 9 *emical analysis4 ,,! ,,iod9e ,,te/ ,,= ,,/>*4 ,a v simple te/ = />*1 b "o t is ?or\ghly reliable1 is ! foll[+3 ,,exp]im5t #aae4 ,mix a little />* ) wat]4 ,add a drop ( iod9e4 ,:at color does ! />* turn8 ,repeat ) sug>4 ,y c tell :at foods h />* 9 !m by te/+ !m ) iod9e4 ,if !y turn black1 blue1 or purple in/ead ( br[n1 y may be sure !re is />* 9 !m4 ,& if !y d n turn black1 blue1 or purple1 y c be equally sure t !y h no />* 9 !m4 ,"s bak+ p[d]s conta9 />* to keep !m dry4 ,te/ ! bak+ p[d] 9 ! laboratory = />*4 ,(t5 a little corn/>* is mix$ ) p[d]$ sug> to keep x f lump+4 ,te/ ! p[d]$ sug> 9 ! laboratory to see if x conta9s />*4 ,te/ ! foll[+ or any o!r t5 foods to see if any ( !m are p>tly made ( />*3 salt1 potatoes1 milk1 meat1 sausage1 butt]1 eggs1 rice1 oatmeal1 cornmeal1 onions4 ,illu/ration3 ,,fig4 #ahh4 ,! :ite p[d] t is =m+ is a silv] salt4 ,,! ,,limewat] ,,te/ ,,= ,,c>bon ,,dioxid4 ,9 cr[d$ & badly v5tilat$ rooms c>bon dioxid 9 unusual am\nts is 9 ! air4 ,x c be detect$ by ! limewat] te/4 ,,exp]im5t #aaf4 ,p\r an in* or two ( limewat] into a glass4 ,does x turn milky8 ,pump ord9>y air ?r\gh x ) a bicycle pump4 ,n[ bl[ air f y\r lungs ?r\gh a glass tube into "s fre% limewat] until x turns milky4 ,by ?is te/ y c always tell if c>bon dioxid 7,,co#b7 is pres5t4 ,illu/ration3 ,,fig4 #ahi4 ,! limewat] te/ %[s t !re is c>bon dioxid 9 ! air4 ,c>bon dioxid turns limewat] milky z x comb9es ) ! lime 9 ! limewat] to make t9y p>ticles 7a precipitate7 ( lime/one4 ,if y p\r seltz] wat] or soda pop into limewat]1 y get ! same milk9ess1 = ! bubbles ( c>bon dioxid 9 ! *>g$ wat] act z ! c>bon dioxid 9 y\r brea? did4 ,if y pump$ en\gh air ?r\gh ! limewat] y w\ld produce "s milk9ess 9 x1 = !re is always "s c>bon dioxid 9 ! air4 ,! purpose ( ^! exp]im5ts is only to give y a g5]al notion ( h[ a *emi/ analyzes ?+s1--by putt+ an unkn[n sub/ance ?r\gh a s]ies ( te/s he c tell j :at t sub/ance conta9s2 & by accurately weigh+ & measur+ ev]y?+ he puts 9 & ev]y?+ he gets out1 he c det]m9e h[ mu* ( ea* ?+ is pres5t 9 ! comp\nd or mixture4 ,to le>n to d ?is accurately takes ye>s ( tra9+4 ,b ! m5 :o g ?r\gh ?is tra9+ & analyze sub/ances = u are among ! mo/ useful memb]s ( ! human race4 ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #eea4 ,a little soda us$ 9 cann+ an acid fruit w save sug>4 #eeb4 ,! fats y eat are mo/ly dige/$ 9 ! small inte/9e1 :]e !re is a l>ge excess ( alkali4 #eec4 ,! dissolv$ food 9 ! liquid "p ( ! blood gets out ( ! blood vessels & 9 among ! cells ( ! body1 & x is f9ally tak5 into ! cells ?r\gh _! walls4 #eed4 ,ammonia takes ! color out ( delicate fabrics4 #eee4 ,di%es 9 :i* *eese has be5 cook$ c be clean$ quickly by boil+ v9eg> 9 !m4 #eef4 ,prep>$ pancake fl\r conta9s bak+ p[d]4 ,x keeps indef9itely :5 dry1 b if ! box gets wet1 x spoils4 #eeg4 ,:5 wat] or milk is add$ to prep>$ pancake fl\r to make a batt]1 bubbles appe> all ?r\gh x4 #eeh4 ,:5 a ro( leaks a little1 a l>ge spot appe>s on ! ceil+4 #eei4 ,gasol9e burns quietly en\gh 9 a /ove1 b if a sp>k gets into a c conta9+ gasol9e vapor1 !re is a viol5t explosion4 #efj4 ,turp5t9e w remove fre% pa9t4 ,,g5]al ,,review ,,inf]5ce ,,ex]cise ,expla9 ! foll[+3 #efa4 ,we c remove fre% /a9s by p\r+ boil+ wat] ?r\gh !m4 #efb4 ,a %ip c be m heavily lad5 9 salt wat] ?an 9 fre% wat]4 #efc4 ,wat] flies (f a wet dog :5 he %akes himself4 #efd4 ,9 cook+ molasses c&y1 bak+ soda is (t5 add$ to make x light]4 #efe4 ,an egg w n /& on end4 #eff4 ,wom5 :o c>ry bundles on _! heads /& up v /raight4 #efg4 ,to get all crayon m>ks (f a blackbo>d1 ! janitor uses v9eg> 9 wat]4 #efh4 ,sunlight makes y\r sk9 d>k]4 #efi4 ,wat] puts out a fire4 #egj4 ,y get a mu* worse %ock f a live wire :5 y\r h&s are wet ?an :5 !y are dry4 #ega4 ,/one or brick build+s are cool 9 summ] b w>m 9 w9t]4 #egb4 ,if y take ! h&le (f a faucet1 x is almo/ impossible to turn ! valve ) y\r f+]s4 #egc4 ,sp>ks fly f a gr9d/one :5 y are %>p5+ a knife4 #egd4 ,viol9 /r+s are spoil$ by gett+ wet4 #ege4 ,! oxyg5 ( ! air gets into ! blood f ! lungs1 al?\gh !re are no holes f ! blood vessels into ! lungs4 #egf4 ,y pu% a button or turn a key swit* & an electric lamp lights4 #egg4 ,a rubb] comb1 rubb$ on a piece ( wool clo?1 w attract bits ( pap] to x4 #egh4 ,p ^: eyes no long] adju/ !mselves h to h read+ glasses & di/ance glasses to see cle>ly4 #egi4 ,:5 y look ?r\gh a triangul> glass prism1 ?+s appe> to be :]e !y are n4 #ehj4 ,lye & hot wat] p\r$ d[n a clogg$ kit*5 dra9pipe cle> out ! grease4 #eha4 ,y c draw on r\gh pap] ) *>coal4 #ehb4 ,:5 little *ildr5 get new %oes1 ! soles %\ld be scrat*$ & made r\gh4 #ehc4 ,y c get y\r face v clean by rubb+ cold cream into x1 !n wip+ ! cold cream (f on a t[el or clo?4 #ehd4 ,s(t pap] blurs writ+ :5 y use ink4 #ehe4 ,wat] w fl[ ov] ! side ( a pan ?r\gh a siphon1 if ! out] end ( ! siphon is l[] ?an ! surface ( ! wat] 9 ! pan4 #ehf4 ,!re is a l\d noise :5 a gun is fir$4 #ehg4 ,color$ clo?s %\ld be mat*$ 9 daylight1 n 9 artificial light4 #ehh4 ,lamp *imneys are made ( ?9 glass4 #ehi4 ,:5 y sweep oil$ floors1 no du/ flies ar\nd ! room4 #eij4 ,! ocean is salty1 :ile lakes are usually fre%4 #eia4 ,a glass gauge on ! side ( a wat] tank %[s h[ high ! ,wat] 9 ! tank is4 #eib4 ,y burn y\r h& :5 y t\* a hot /ove4 #eic4 ,p\nd+ a piece ( /eel held horizontally ov] ! e>? & po9t+ nor? & s\? w make x become a magnet4 #eid4 ,:5 only "o side ( a sponge is 9 wat]1 ! sponge gradually gets s(t all ov]4 #eie4 ,if we brea! on a cold mirror1 a f9e mi/ collects on x4 #eif4 ,butt] is kept 9 cool places4 #eig4 ,wat] w boil m quickly 9 a cov]$ pan ?an 9 an op5 "o4 #eih4 ,mucilage1 glue1 & pa/e all become h>d & dry aft] be+ spread out on a surface = a :ile4 #eii4 ,y _c see ?+s cle>ly ?r\gh a du/y w9d[4 #fjj4 ,9 mak+ fire grates x is necess>y to h ! b>s free to move a little4 ,,app5dix ,a4 ,,! ,,electrical ,,app>atus ,= giv+ *ildr5 a practical und]/&+ ( su* laws ( electricity z affect ev]ybody1 ! foll[+ simple app>atus is invaluable4 ,x is ! electrical app>atus ref]r$ to sev]al times 9 ! text4 ,! only "p ( x t is at all difficult to get is ! ni*rome resi/ance wire4 ,!re is a monopoly on ?is & ea* lic5see has to agree n to sell x4 ,x c be b\ght direct f ! manufactur] by ! s*ool bo>d if a /atem5t accompanies ! ord] to ! effect t x is n to be us$ 9 any comm]cial devices1 nor to be sold1 b is = laboratory exp]im5tation only4 ,! manufactur]s are ,hosk9s ,manufactur+ ,company1 ,detroit1 ,mi*igan4 ,! foll[+ diagram w make ! connections & p>ts ( ! electrical app>atus cle>3 ,illu/ration3 ,,fig4 #aij4 ,electrical app>atus3 ,at ! "r are ! incom+ wires4 ,dott$ l9es %[ outl9es ( fuse block4 ,a1 #b c>tridge fuses1 #ae ,a2 ,b1 #b plug fuses1 #aj ,a2 ,c1 knife swit*2 ,d1 fuse gap2 ,e1 snap swit*2 ,f1 ,h1 lamp sockets2 ,g1 flu% swit*2 ,i1 ,j1 ,k1 ni*rome resi/ance wire1 ,no4 #bd 7total l5g? ( loop1 #f feet71 pass+ ar\nd porcela9 po/s at left4 ,! flu% swit* 7,g7 %\ld be op5 at ! bottom = inspection1--remove ! back4 ,! snap swit* 7,e7 %\ld h cov] remov$ s t pupils c see exactly h[ x works4 ,! fuse gap 7,d7 consi/s ei!r ( two p>ts ( an old knife swit*1 ! knife remov$1 or ( two brass b9d+ po/s4 ,across x a piece ( #d-;amp]e fuse wire is always kept z a protection to ! m exp5sive plug & c>tridge fuses4 ,betwe5 ! resi/ance wire 7,i1 ,j1 ,k7 & ! wall %\ld be ei!r slate or %eet asbe/os1 d\ble ?ickness4 ,"u ! fuse gap ! table %\ld be protect$ by galvaniz$ iron s t ! melt$ bits ( fuse wire c set no?+ on fire :5 ! fuse wire burns out4 ,b4 ,,con/ruction ,,( ,,! ,,cig>-,,box ,,telegraph ,! cig>-box telegraph %[n on page #cha is made z foll[s3 ,an iron ma*9e bolt 7,a7 is w\nd ) ab\t ?ree lay]s ( ,no4 #bd insulat$ copp] magnet wire1 ! two ends ( ! wire 7,b1 ,b7 project+4 ,! ?read$ end ( ! bolt 7,c7 is n w\nd4 ,a nut 7,d7 is screw$ on ! bolt z f> d[n z ! wire wrapp+4 ,! ?read$ end is !n pu%$ up ?r\gh ! hole 9 ! top ( ! cig> box z t /&s on its edge4 ,ano!r nut 7,e7 is !n screw$ on to ! bolt1 hold+ x 9 position4 ,! bolt c n[ be rais$ or l[]$ & tight5$ firmly 9 position by adju/+ ! two nuts 7,d & ,e71 "o above & "o bel[ ! wood4 ,a screw eye 7,f71 l>ge en\gh to =m a re/ = ! head ( ano!r ma*9e bolt 7,g71 is screw$ into ! back ( ! box ab\t ?ree f\r?s ( an in* bel[ ! head ( ! susp5d$ bolt 7,a74 ,two or ?ree in*es away1 at a slightly high] level1 ano!r screw eye 7,h7 is screw$ into ! back ( ! cig> box4 ,?is screw eye mu/ h an op5+ l>ge en\gh to p]mit an iron ma*9e bolt 7,g7 to pass ?r\gh x easily4 ,a nut 7,i7 is screw$ d[n on ! ?read$ end ( a ma*9e bolt until ab\t an in* ( ! bolt projects beyond ! nut4 ,?is project+ "p ( ! bolt is !n pass$ ?r\gh ! screw eye 7,h7 & ano!r nut 7,j7 screw$ on to x to hold x 9 place4 ,?is nut mu/ n be s tight z to prev5t ! free play ( ! bolt z its head rises & falls "u ! influ5ce ( ! v]tical bolt4 ,! head ( ! horizontal bolt re/s ^u ! screw eye :i* is imm$iately bel[ ! head ( ! susp5d$ bolt4 ,y !re=e h ! wrapp$ bolt hang+ v]tically f ! top ( ! box1 ) its head j ov] ! head ( ! horizontal bolt4 ,!re %\ld be ab\t "o qu>t] in* ( space betwe5 ! heads ( ! two bolts4 ,an electric curr5t pass+ ?r\gh ! wires ( ! v]tical bolt w !re=e lift ! head ( ! horizontal bolt1 :i* w drop back on to ! screw eye :5 ! circuit is brok54 ,illu/ration3 ,fig4 #aia4 ,! cig>-box telegraph4 ,,index ,an a/]isk 7997 indicates use ( "o or m illu/rations 9 connection ) ref]5ce to :i* app5d$4 ,acetyl5e1 c>bon & hydrog5 91 #cae4 ,acids1 #cea ff42 action (1 on metals1 #cea-cec992 action (1 on clo?1 #ced992 action (1 on n]ves ( ta/e1 #ced-cee2 di/+ui%$ f bases by litmus te/1 #ceh-cei2 neutralization (1 by bases1 #cfj-cfd4 ,action & reaction1 law (1 #gg-ha994 ,adhesion1 #ci1 #da-dd2 cohesion1 capill>y attraction1 &1 #dg4 ,air1 cool+ (1 on exp&+1 #ie-if2 liquid1 #ig2 heat c>ri$ by1 by convection1 #aah-aai2 absorption ( light by1 #afi2 s\nd produc$ by vibrations (1 #agd-aha992 pit* due to rapidity ( vibrations (1 #ahf2 wat] vapor 91 #bge-bhj992 a mixture & n a comp\nd1 #cji2 "p tak5 by1 9 mak+ automobile g1 #cdd2 limewat] te/ = c>bon dioxid 91 #cge4 ,air pressure1 #aj ff41 #ad992 height wat] is =c$ up by1 9 vacuum1 #ai2 high & l[1 #bj1 #bhb2 w9ds caus$ by1 #bj-ba4 ,air pump1 #ad991 #ae4 ,alcohol1 boil+ (1 #aab2 di/ill+1 #aac99-aad4 ,alkali1 #cef2 9 soap1 #ceg-ceh4 ,alloys1 def9ition (1 #caj4 ,alt]nat+ curr5t1 def9$1 #baa-bab4 ,alum cry/als1 exp]im5t )1 #bfe-bff994 ,alum9um1 an elem5t1 #bii4 ,alum 9 wat]1 te/+ ) litmus pap]1 #cei4 ,amb]1 electricity produc$ by rubb+ ) silk1 #aif4 ,ammonia1 example ( a common base1 #cef2 action (1 9 clean+ clo?1 #ceh2 litmus te/ (1 #cei2 neutralization ( acid by1 #cfc4 ,amp]e1 def9$1 #bdf4 ,analysis1 *emical1 #cgj-cgf4 ,an]oid b>omet]1 #bhe994 ,arc1 ! electric1 #bcc-bdj994 ,atoms1 description (1 #aif2 electrons &1 #aig2 ev]y?+ 9 ! _w made (1 #caj-caa2 9 molecules1 #caa4 ,aurora ,borealis1 cause (1 #aic4 ,automobile1 reason = crank+1 #baj2 h[ made to g1 #cdd-cde4 ,automobile races1 ov]com+ ( c5trifugal =ce 91 #ge994 ,automobile tires1 reason = we>+ (1 #hj2 bl[-outs (1 #cdh4 ,bak+ p[d]1 *emical *ange by solution %[n by1 #cdi-cej2 elem5ts ( :i* made1 #cfg-cfh4 ,bak+ soda1 a common base1 #cef2 te/+ ) litmus pap]1 #cei2 neutralization ( s\r milk by1 9 cook+1 #cfb2 c>bon dioxid 91 #cff-cfg4 ,ball be>+s1 us$ to dim9i% friction1 #ed-ee4 ,balloon1 expansion (1 #ag-ah1 #aji992 reason = ris+ (1 #bf2 fill+ (1 ) hydrog51 #cja-cjd994 ,b>omet]1 use (1 #bhj-bhe994 ,bases1 sub/ances call$1 #cee-ceh2 litmus te/ = di/+ui%+ f acids1 #ceh-cei2 neutralization (1 by acids1 #cfj-cfd4 ,batt]ies1 electric1 #bjc-bje992 diff]5t k9ds (1 #bje99-bjg992 g5]al pr9ciple ( all1 #bjf4 ,bell1 electric batt]y = r++1 #bjd-bje992 work+ ( electric1 #bee994 ,b5d+ ( light 7refraction71 #acf-ada994 ,black1 ! abs5ce ( light1 #afd4 ,blea*+1 process (1 #cbf-cbg4 ,bl[-out ( tire1 a real explosion1 #cdh4 ,blue-flame heat]s1 #cai4 ,blu5ess ( sky1 reason =1 #afi4 ,bluepr9ts1 mak+ (1 #ccj-cca4 ,boil+ & cond5s+1 #ajg-aae994 ,borax bead te/1 #cga99-cgb994 ,brass1 an alloy1 #caj4 ,bread mak+1 *emical action 91 #cfe4 ,brea?1 cause ( visibility (1 on cold days1 #bhh1 #bhi994 ,bronze1 an alloy1 #caj4 ,burn+1 explanation (1 #cjh1 #cab-cac4 ,calcium *lorid1 #aad4 ,cam]a1 l5s (1 #adc1 #adh2 human eye z a small1 #aea99-aec2 explanation (1 #cbg-ccb4 ,capill>y attraction1 #cf99-dj2 diff]5ce betwe5 adhesion1 cohesion1 &1 #dg4 ,c>bon1 9 electric batt]y1 #bjc-bjf2 resi/ance (1 to electric curr5t1 #bca2 an elem5t1 #bic1 #bii2 "o ( *ief elem5ts 9 fuel1 #cae-caf4 ,c>bon dioxid1 9 seltz] siphon1 #ag2 produc$ by jo9+ ( c>bon ) oxyg51 #cae2 comb9+ ( wat] &1 by plants1 #ccb-ccc2 releas+ (1 9 bak+ p[d]1 #cdi-cej2 bubbl+ (1 9 eff]vesc5ce1 #cfe-cff2 9 soda wat]1 spr+s1 & bak+ soda1 #cff-cfg2 limewat] te/ =1 #cge-cgf4 ,c>bonic acid gas1 comm]cial "n = pure c>bon dioxid1 #cfe-cff4 ,cat's hairs1 /atic electricity 91 #bja4 ,cau/ic soda1 a common base1 #cef4 ,c5t] ( weight1 #cj-cc994 ,c5trifugal =ce1 #e1 #gb-gd2 law (1 #gd-ge4 ,*>coal1 production (1 #caf4 ,*>g+ wat] ) c>bon dioxid1 #cff4 ,*emical analysis1 #cgj-cgf4 ,*emical *ange1 & en]gy1 #bic ff42 burn+ 7oxidation71 #cab-cbb2 caus$ by heat1 #cbc-cbe2 caus$ by light1 #cbf-cce2 caus$ by electricity1 #cce-cci2 en]gy releas$ by1 #cdj-cda2 help$ by solution1 #cdi-cea4 ,*emical equations1 #big-bii4 ,*lor9e1 an elem5t1 #bii4 ,*lorophyll 9 plants1 "w (1 #ccb4 ,cig>-box telegraph1 con/ruction (1 #bdi991 #chj-cha994 ,circuits1 electric1 #bai-bbj992 break+ & mak+1 #bbj-bba2 connect+ 9 p>allel1 #bba-bbc992 gr\nd$1 #bbe-bbi992 %ort1 #bdj-bde994 ,clo?1 action ( acids on1 #ced992 action ( an alkali on1 #cef1 #ceg994 ,cl\ds1 h[ =m$1 #bgg-bgh4 ,coal1 c>bon & hydrog5 91 #cae4 ,cohesion1 #ci1 #dd99-di4 ,cold1 caus$ by expansion1 #id2 is ! abs5ce ( heat1 #ie1 #abj4 ,color1 #afa-agb994 ,comb1 electricity produc$ by rubb+1 #aig-aih4 ,compass1 use (1 #aij-aie994 ,complete electric circuits1 #bai-bbd994 ,comp\nds1 h[ elem5ts hide 91 #cjj2 def9ition (1 #cjh-cji2 mixtures di/+ui%$ f1 #cji-caj4 ,concave mirrors1 #aed991 #aee991 #aeg2 magnification by1 #aeg2 9 reflect+ telescopes1 #aeg4 ,conduction1 ( heat1 #aaf-aah2 ( electricity1 #bac-bah4 ,conductors ( electricity1 good & poor1 #bac4 ,conduits = electric wires1 #bcg4 ,cons]vation ( en]gy1 #eg ff4 ,convection1 c>ry+ ( heat by1 #aah-aai4 ,convex l5s1 #adh-adi992 9 microscope1 #aee-aeg992 9 telescope1 #aeg4 ,cool+ f expansion1 #id-if4 ,coolness at night & 9 w9t]1 #abg-abh4 ,copp]1 a good conductor ( electricity1 #bae2 an elem5t1 #bii2 nickel plat+ (1 #ccf-cci992 et*+ (1 ) acid1 #ceb99-cec4 ,copp] nitrate1 salt call$1 #cec4 ,cream1 sep>at+ f milk1 by c5trifugal =ce1 #ge-gf4 ,cry/als1 =mation (1 #bfe-bfh4 ,cyl9d] ( eng9e1 #cdd994 ,dead ,sea1 reason = salt 91 #ajd-aje994 ,decay1 a k9d ( oxidation1 #cac4 ,dew1 #bge2 h[ =m$1 #bhg4 ,dictaphone1 work+ (1 #age1 #agh1 #agi994 ,diffusion1 #bfh-bgd2 ( light1 #aeh-afa4 ,direct-curr5t electricity1 #baa-bab4 ,di/ill+ ( liquids1 #aab-aae994 ,doorbell1 electric batt]y = r++1 #bjd-bje4 ,d[n1 mean+ ( ^w1 #d4 ,dra9pipe1 clean+ (1 ) lye1 #ceh4 ,dry-cell batt]y1 #bjf994 ,du/1 reason = cl++ to walls1 #dc-dd4 ,dynamite1 #cdc992 mak+ (1 #cdg4 ,dynamo1 h[ electric curr5t is made to fl[ by1 #bjg99-baj994 ,e>?1 magnetism (1 #aij-aie4 ,easy circuit1 a %ort circuit an1 #bdd-bde4 ,e*oes1 explanation (1 #ahc-ahe4 ,eff]vesc5ce1 process (1 #cfe2 g5]ally due to free+ ( c>bon dioxid1 #cfg99-cfh2 help$ by /irr+ or %ak+1 #cfh4 ,ela/icity1 #hb-hf2 ( =m di/+ui%$ f ela/icity ( volume1 #hf-hg4 ,electrical app>atus1 #baf-bag991 #bbb-bbc992 description (1 #cgi-chj4 ,electric arc1 !1 #bcc99-bdj4 ,electric batt]y1 !1 #bjc-bjf994 ,electricity1 magnetism &1 #aij ff42 /atic1 #aif-bjb2 negative & positive *>ges (1 #aih99-bjj2 action (1 9 ?und]/orms1 #bjj-bja2 fl[+1 #bjc ff42 fl[+ (1 9 dynamo1 #bjg-baj2 alt]nat+ & direct-curr5t1 #baa-bab2 conduction (1 #bac99-bah2 *emical *ange caus$ by1 #cce-cci4 ,electric lamps1 vacuums 91 #ab991 #cag2 inc&esc5t1 #abe2 gas-fill$1 #cag4 ,electric motors1 #bef99-beg994 ,electrolysis app>atus1 #bid-bie994 ,electromagnets1 #bdg-beg994 ,electrons1 #aic2 description (1 #aig2 numb] (1 9 negative & 9 positive *>ges1 #aih-bjj4 ,elem5ts1 def9$1 #bic2 *emi/s' abbreviations (1 #big-bii2 li/ ( common1 #bii-cjj2 hid+ (1 9 comp\nds1 #cjj-cja4 ,emulsion1 def9$1 #bfa2 diff]5ce betwe5 solution &1 #bfc4 ,en]gy releas$ by *emical *ange1 #cdj-cda4 ,eng9e1 work+ ( cyl9d] & pi/on (1 #cdd994 ,e!r1 c>ry+ ( heat & light by1 #abd-abe2 light z waves (1 #afc-afd4 ,e!r waves1 #abd-abe1 #afc-afd4 ,evaporat+ di%1 #aja994 ,evaporation1 #ajj-ajf992 "p tak5 by1 9 =mation ( cl\ds1 ra91 & dew1 #bgg4 ,expansion1 caus$ by heat1 #hh-ic2 cool+ f1 #id-if994 ,expansion ball & r+ exp]im5t1 #ia99-ib4 ,explosions1 use (1 #cdb99 ff42 automobiles made to g by succession (1 #cdd-cde2 cause (1 #cde2 %oot+ ( guns caus$ by1 #cde-cdf4 ,explosives1 manufacture (1 #cdg4 ,ext5sion lights1 #bch4 ,eye1 l5s (1 #adb2 section (1 #aea992 work+ (1 #aea99-aec4 ,fad+1 process (1 #cbf-cbg4 ,filam5t ( inc&esc5t lamp1 #abe4 ,fire eng9es1 ne$ (1 to =ce wat] high1 #i4 ,fire ext+ui%]s1 action (1 #cag4 ,fires1 caus$ by electric arcs1 #bcf2 putt+ out (1 by wat]1 #cag4 ,see ,burn+4 ,flames1 =mation (1 #cah4 ,float+1 s9k+ &1 #bc-bh4 ,focus ( light1 #adb99-adi994 ,fogs1 cause (1 #bhh4 ,food1 light necess>y to production (1 #ccb-ccc4 ,=ce1 ov]com+ ( extra motion by1 9 lev]1 #fc-fd992 reason =1 ( /eam1 #aaj4 ,=eca/]s1 wea!r1 #bhb-bhe4 ,=m1 ela/icity (1 #hf-hg4 ,freckles1 cause (1 #cbg4 ,freez+ & melt+1 #if-ii4 ,friction1 #di-ee992 electricity produc$ by1 #aig-aih994 ,fro/1 #ig1 #bge2 explanation (1 #bhg4 ,fuel1 *ief elem5ts 91 #cae-caf4 ,fulcrum ( lev]1 #ei-fj994 ,fuse gap1 !1 #bda991 #cgi994 ,fuses1 %ort circuits &1 #bdj-bde4 ,gas1 cool+ (1 on exp&+1 #id-ie2 c>bon & hydrog5 91 #cae2 us$ = fill+ electric lamps1 #cag-cah2 w n burn until hot en\gh1 #cbc-cbd2 an explosion ! sudd5 release ( a conf9$1 #cdh4 ,gases1 diffusion (1 #bfi-bga2 z elem5ts1 #bic-bid4 ,gas heat]s1 action (1 #cai1 #cba991 #cbb994 ,gasol9e1 evaporation (1 #ajc2 boil+ (1 #aab2 di/ill$ f petroleum1 #aad2 elem5ts (1 #cae2 action (1 9 mak+ automobiles g1 #cdd-cde4 ,geys]s1 cause (1 #aaj4 ,glass1 a poor conductor ( heat1 #aah2 us$ z insulator ( electricity1 #bae4 ,gl[worms1 reason = gl[+ (1 #cda-cdb4 ,gold1 an elem5t1 #bic1 #bii2 plat+ (1 #cci4 ,gravitation1 def9$1 #c4 ,gravity1 #a2 pull (1 oppos$ to pull ( adhesion1 #db-dc4 ,grease1 friction dim9i%$ by1 #ec-ed2 comb9$ ) lye to =m soap1 #ceg4 ,great ,salt ,lake1 reason = salt 91 #ajd-aje4 ,greeks1 e>ly k ( electricity possess$ by1 #aif4 ,gre5 color ( wat]1 reason =1 #afi-aga994 ,gr\nd$ circuits1 #bbe-bbi994 ,gun1 %oot+ (1 caus$ by explosion1 #cde-cdf4 ,gunp[d]1 action (1 9 %oot+ ( a gun1 #cde-cdf2 h[ made1 #cdg4 ,hail1 explanation (1 #bhf4 ,heat1 a result ( friction1 #ec2 is ! motion ( molecules1 #ij2 n caus$ by expansion1 #id-ie2 cold is abs5ce (1 #ie1 #abj2 requir$ to evaporate liquids1 #ajb-ajc2 conduction (1 #aaf-aah2 c>ri$ by air1 by convection1 #aah-aai2 radiation (1 #abb-abh2 ( inc&esc5t lamp1 #abe-abf2 br\ght to focus by convex l5s1 #adi2 *emical *ange caus$ by1 #cbc-cbe4 ,heat]s1 hot-wat]1 #abj992 electric1 #bcj1 #bcb2 gas1 #cai1 #cba991 #cbb994 ,heat waves1 cause (1 #ada4 ,hydro*loric acid1 gett+ hydrog5 f1 #cja-cjd2 te/+ = silv] )1 #cgc4 ,hydr(luoric acid1 #cea4 ,hydrog51 an elem5t1 #bid1 #bii2 9 wat]1 #bie-bif2 exp]im5ts )1 #cja-cjd992 "o ( *ief elem5ts 9 fuel1 #cae-caf2 "p tak5 by1 9 burn+1 #cab-cai4 ,ice1 slight friction (1 #eb992 action ( molecules 91 on freez+ & melt+1 #if-ig2 reason = float+ (1 #ih-ii4 ,inc&esc5ce1 def9$1 #abe4 ,inc&esc5t lamps1 #abe-abf2 numb] ( electrons 91 #aig2 work+ (1 #bbi-bcb4 ,in]tia1 #ff-ga2 def9ition (1 #gj4 ,insulators1 ( heat1 #aah2 ( electricity1 #bac2 sub/ances us$ z1 #bae4 ,iod9e1 an elem5t1 #bii2 te/+ )1 = />*1 #cgc-cgd4 ,iron1 a good conductor ( heat1 #aah2 an elem5t1 #bii4 ,irons1 electric1 #bbi991 #bcj1 #bcb4 ,iron salt1 =m$ by lemon juice on /eel1 #cec4 ,iron %ips1 reason = float+1 #bd99-bf4 ,k]os5e1 boil+ (1 #aab2 di/ill$ f petroleum1 #aad2 c>bon & hydrog5 91 #cae4 ,laugh+ gas1 #cji4 ,lava 9 volcanoes1 #aaj4 ,lead1 an elem5t1 #bii4 ,lead p5cils1 arc light f1 #bcc99-bcd994 ,lean+ ,t[] ( ,pisa1 #bi99-cj4 ,lemon juice1 action (1 on silv] & on /eel1 #cec2 litmus te/ (1 #cei4 ,l5s1 ( eye1 #adb1 #aea99-aec2 ( cam]a1 #adc1 #adi991 #cbh2 convex1 #adh-adi2 concave1 #adi992 9 telescope1 #aeg4 ,lev]s1 #eg-fe994 ,light1 radiation (1 #abb1 #abc99-abh2 reflection (1 #abi-ace992 refraction (1 #acf99-ada2 focus (1 #adb-adi992 br\ght to focus by convex l5s1 #adi2 diffusion (1 #aeh-afa992 color a k9d (1 #afb2 spe$ (1 #ahb2 *emical *ange caus$ by1 #cbf-cce2 & manufacture ( food 9 plants1 #ccb-ccc4 ,lightn+1 cause (1 #bjj-bja4 ,limewat] te/ = c>bon dioxid1 #cge99-cgf4 ,liquid air1 #ig1 #aab4 ,liquids1 absorption (1 #cf-dj2 diffusion 91 #bgb4 ,litmus pap]1 exp]im5ts )1 #ceh-cei4 ,litmus te/1 !1 #ceh-cei4 ,lye1 a common base1 #cef2 exp]im5t )1 #cef2 soap made f1 #ceg2 us$ = cle>+ out dra9pipe1 #ceh2 neutralization (1 by acids1 #cfc4 ,ma*9]y1 oil+ (1 to decrease friction1 #ec-ed4 ,magdeburg hemisph]es1 #ae1 #af99-ag4 ,magnetism1 #aij ff4 ,magneto1 ( automobile1 #baj1 #baa992 ( old-fa%ion$ telephone1 #baj-baa4 ,magnets1 #aij-aie994 ,magnification1 #aej-aeg2 by concave mirror1 #aeg4 ,magnify+ glass1 convex l5s 91 #adi2 op]ation (1 #aej-aef994 ,manganese dioxid1 an ess5tial 9 explosives1 #cdg4 ,megaphone1 work+ (1 #ahd4 ,melt+1 freez+ &1 #if-ii4 ,membrane1 diffusion ?r\gh a1 #bgb4 ,m]cury1 cohesion (1 #dg-dh992 use (1 9 !rmomet]1 #hi991 #ij-ia2 an elem5t1 #bii4 ,m]cury-vapor lamps1 #afg-afh991 #agb4 ,metals1 good conductors ( heat1 #aah2 good conductors ( electricity1 #bae2 z elem5ts1 #caj2 plat+ (1 #ccf-cci992 action ( acids on1 #cea-cec4 ,microscope1 #hh2 work+ (1 #aee-aeg994 ,mirrors1 concave1 #aed991 #aee991 #aeg4 ,mixtures1 di/+ui%$ f comp\nds1 #cji-caj4 ,molecul> attraction1 #cf ff4 ,molecules1 pull (1 on ea* o!r1 #df-dg2 explanation (1 #hh-hi2 heat def9$ z ! motion (1 #ij2 action (1 9 evaporation1 #ajb-ajc992 action (1 9 boil+ wat]1 #ajg2 action (1 9 conduction ( heat1 #aag2 action (1 9 radiation ( heat & light1 #abe2 action (1 9 magnetiz+1 #aid99-aie2 made up ( atoms1 #aif1 #caj2 m+l+ (1 #bei ff42 action (1 9 =mation ( cl\ds1 ra91 & dew1 #bgg4 ,moon1 cause ( r+ ar\nd1 #aca4 ,morse telegraph code1 #bec4 ,motion-picture ma*9es1 l5ses (1 #adc1 #adh4 ,motor1 ! electric1 #bee-beg994 ,m\nta9s1 ra9fall on1 #bhf-bhg4 ,musical in/rum5ts1 pit* (1 #ahe-ahg991 #ahh2 vibrat+ devices (1 #ahh4 ,nail plug1 !1 #bda991 #cgi994 ,ne$le1 magnetiz+ (1 #aib991 #aic99-aie4 ,negative *>ges ( electricity1 #aih-bjj4 ,neutralization ( acids & bases1 #cfj-cfd4 ,niag>a ,falls1 electricity g5]at$ by1 #baj4 ,nickel1 an elem5t1 #bii4 ,nickel-plat+ copp]1 process (1 #ccf-cci994 ,night1 reason = coolness at1 #abg-abh4 ,nitric-acid1 et*+ copp] )1 #ceb99-cec2 action (1 on clo?1 #ced994 ,nitrog51 an elem5t1 #bii2 a non-burn+ gas1 #cjh2 us$ 9 electric lamps1 #cag4 ,nor!rn ,lights1 cause (1 #aic4 ,ocean1 :y salt1 #ajd-aje4 ,oil1 reason = float+ (1 #bf-bg2 decreas+ ( friction by1 #ec-ed2 s(t5+ due to1 #bij-bib2 c>bon & hydrog5 9 crude1 #cae2 :y wat] w n put out burn+1 #cag4 ,oil heat]s1 action (1 #cai4 ,orange1 litmus te/ (1 #cei4 ,osmosis1 process call$1 #bgb-bgd4 ,osmotic pressure1 #bgb-bgc994 ,oxidation1 #cab-cbb4 ,oxyg51 an elem5t1 #bic1 #bii2 an elem5t ( wat]1 #bie-bif2 exp]im5ts 9 gett+1 f two solids1 #cje-cjh992 function (1 9 burn+1 #cjh2 "p tak5 by1 9 burn+ 7oxidation71 #cab-cac2 releas$ 9 manufacture ( plant food1 #ccc-cce2 a comp\nd (1 an ess5tial 9 explosives1 #cdg4 ,pancakes1 made f s\r milk1 #cfb4 ,pap]1 c>bon & hydrog5 91 #cae4 ,p>aff9e1 production (1 #aad4 ,p>allel circuits1 #bba-bbc994 ,peat1 c>bon & hydrog5 91 #cae4 ,p5cils1 mak+ arc light )1 #bcc99-bcd994 ,p]iscope exp]im5t1 #acd-ace994 ,petroleum1 gasol9e & k]os5e di/ill$ f1 #aad4 ,phonograph1 work+ (1 #agg-agh994 ,phosphoresc5ce1 cause (1 #cda-cdb4 ,phosphorus1 an elem5t1 #cjj2 mean+ ( "n1 #cda4 ,photographs1 process ( mak+1 #cbg-ccb994 ,pit* ( s\nd1 explanation (1 #ahe-ahh994 ,plants1 light & ! manufacture ( food 91 #ccb-ccc2 h[ oxyg5 is suppli$ by1 #ccc-cce4 ,plat+ ( metals1 #ccf-cci994 ,plat9um1 an elem5t1 #cjj4 ,poles1 positive & negative1 #bjf-bjg4 ,porcela91 us$ z insulator1 #bae4 ,positive *>ges ( electricity1 #aih-bjj4 ,potassium1 exp]im5t )1 #cjd4 ,potassium *lorate1 an ess5tial 9 explosives1 #cdg4 ,preci\s /ones1 =mation (1 #bfc-bfd4 ,prism1 refraction ( light by1 #acf-adj992 sep>ation ( light into ra9b[ colors by1 #afb-afc994 ,quicksilv]4 ,see ,m]cury4 ,radiation ( heat & light1 #abb99-abh4 ,radium1 an elem5t1 #cjj4 ,ra91 #bge2 cause (1 #bgh-bhj4 ,ra9b[1 mak+ a1 on wall1 #afb99-afc2 h[ =m$1 #agj-aga4 ,read+ glasses1 #add992 convex l5s 91 #aej4 ,r$ color ( sky at sunset1 reason =1 #agj4 ,reflect+ telescopes1 #aeg4 ,reflection ( light1 #abi-ace994 ,refraction ( light1 #acf-ada994 ,resi/ance1 electrical1 #bbi-bcb4 ,ret9a ( eye1 #aea991 #aec4 ,rev]b]ation ( s\nd1 #ahc-ahe4 ,r+ ar\nd moon1 cause (1 #aca4 ,rock c&y1 h[ made1 #bfg4 ,rubb]1 us$ z insulator1 #bae4 ,ru/+ ( iron1 #cdi4 ,safety valves on /eam boil]s1 #cdg4 ,salt1 reason =1 9 sea1 #ajd-aje992 a comp\nd1 #cjh2 elem5ts (1 #caj-caa2 =m$ by hydro*loric acid & z9c1 #cea2 iron1 =m$ by lemon juice on /eel1 #cec2 acids & bases turn$ to wat] &1 by comb9+1 #cfa-cfb4 ,salt wat]1 litmus te/ (1 #cei4 ,samson cells1 #bjd4 ,scatt]+ ( light 7diffusion71 #aeh-afa994 ,seesaw1 example ( a lev]1 #eg-eh994 ,seltz] siphon1 work+ (1 #ag4 ,%ips1 reason = float+1 #bd99-bf4 ,%ock1 electrical1 #bad-bae4 ,%ort circuits & fuses1 #bdj-bde4 ,silv]1 an elem5t1 #cjj2 plat+ (1 #cci2 hydro*loric acid te/ =1 #cgc4 ,silv] *lorid1 =mation (1 #cbg4 ,s9k+ & float+1 #bc-bh994 ,siphon1 #ah994 ,sky1 reason :y blue1 #afi2 :y r$ at sunset1 #agj4 ,smoke1 consi/5cy (1 #cah-cai4 ,sn[1 #bge2 =mation (1 #bhe-bhf4 ,sn[flakes1 #ig1 #bhf994 ,soap1 h[ made1 #ceg-ceh4 ,soda wat]1 h[ made1 #cfe-cff4 ,sodium1 exp]im5t )1 #cjd4 ,s(t5+ due to oil or wat]1 #bij-bib4 ,soil1 litmus te/ (1 #cei4 ,solution1 def9$1 #bfa2 diff]5ce betwe5 emulsion &1 #bfc2 a mixture & n a comp\nd1 #cji2 *emical *ange help$ by1 #cdi4 ,s\nd1 cause (1 #agd2 rate ( spe$1 #aha-ahb2 action (1 9 e*oes1 #ahc-ahe992 pit* (1 #ahe-ahh4 ,s\r milk1 litmus te/ (1 #cei2 neutralization (1 by bak+ soda1 #cfb4 ,s\rness1 ta/e (1 caus$ by acids1 #cec1 #ced-cee4 ,spectroscope1 use ( !1 #agb4 ,spectrum1 !1 #agb4 ,spr+ wat]1 c>bon dioxid 91 #cff4 ,/ability1 #bi-cd4 ,/>*1 iod9e te/ =1 #cgc-cgd4 ,/>s1 tw9kl+ (1 #ada2 h[ to tell ( :at made1 #aga-agb4 ,/atic electricity1 #aif-bjb994 ,/eam1 reason = =ce ex]t$ by1 #aaj2 geys]s & volcanoes caus$ by1 #aaj2 real1 n visible1 #aab n4 ,/eel1 g5]ally an alloy1 #caj4 ,/]eopticons1 l5ses (1 #adh4 ,/orage batt]y1 #bjf1 #bjg992 action ( electricity 91 #cci4 ,/oves1 electric1 #bcj1 #bcb4 ,/reet c>1 electric motor (1 #bee-beg4 ,suction pump1 #ai994 ,sug>1 mak+ (1 by plants1 #ccb-ccc2 litmus te/ (1 #cei4 ,sulfur1 an elem5t1 #cjj4 ,sulfuric acid1 action (1 on clo?1 #ced2 litmus te/ (1 #cei4 ,sun1 radiation ( heat & light f !1 #abb-abh2 h[ to tell ( :at made1 #aga-agb4 ,sunbeams1 explanation (1 #aca4 ,sweat gl&s1 function (1 #bia4 ,tann+1 process (1 #cbg4 ,telegraph app>atus1 #bdg-beb991 #chj-cha994 ,telegraph code1 #bec4 ,telephone1 work+ (1 #bec-bee4 ,telescopes1 #aef991 #aeg2 h[ made1 #aeg2 reflect+1 #aeg4 ,temp]ature1 f9d+ !1 by read+ a !rmomet]1 #ij-ia4 ,!rmomet]1 !1 #hi99-ia994 ,!rmos bottle1 h[ made1 #abf-abg994 ,?und]1 cause (1 #bjj-bja4 ,t91 an elem5t1 #cjj4 ,t9 salt1 poison\s1 #cec4 ,toa/]s1 electric1 #bcj1 #bcb4 ,tomatoes1 use ( soda to neutralize acid (1 #cfb-cfc4 ,tung/51 9 inc&esc5t lamps1 #bca4 ,tun+-=k exp]im5ts1 #aha991 #ahf-ahg994 ,tw9kl+ ( />s1 cause (1 #ada4 ,up1 mean+ ( ^w1 #d4 ,vacuum1 def9$1 #aa2 reason =1 9 electric lamp1 #ab991 #cag2 use (1 9 manufacture ( !rmos bottles1 #abf-abg992 impossibility ( produc+ s\nd 91 #agf-agg4 ,valves1 safety1 on boil]s1 #cdg4 ,vasel9e1 production (1 #aad4 ,vibrations1 ( air1 #agd-aha992 pit* due to rapidity (1 #ahf4 ,v9eg>1 litmus te/ (1 #cei2 neutralization ( lye by1 #cfc4 ,viol91 tun+ (1 #ahg4 ,volcanoes1 cause (1 #aaj2 explosions &1 #cdf994 ,volume1 ela/icity (1 #hf-hg4 ,wa%+ soda1 a common base1 #cef2 litmus te/ (1 #cei4 ,wat]1 seeks its own level1 #f-aj2 gurgl+ (1 :5 p\r$ f bottle1 #ac2 exp]im5t )1 to %[ c5trifugal =ce1 #gc-gd2 us$ = mak+ !rmomet]1 #ij99-ib2 expansion (1 :5 froz51 #ih2 evaporation (1 #ajj-ajf2 action (1 9 geys]s & volcanoes1 #aaj2 absorption ( light by1 #afi-agj2 z conductor ( electricity1 #baf2 use (1 = g5]at+ electricity1 #bef-beg2 s(t5+ due to1 #bij-bib2 elem5ts (1 #bid-big2 a comp\nd & n a mixture1 #cjh2 =m$ by burn+ fuel1 #caf2 :y fire is put out by1 b n burn+ oil1 #cag2 comb9+ ( c>bon dioxid &1 by plants1 #ccb-ccc2 ru/+ ( iron by1 #cdi2 acids & bases turn$ to salt &1 by comb9+1 #cfa-cfb4 ,we>1 a result ( friction1 #ec4 ,wea!r1 =eca/+ (1 #bhb-bhe4 ,weight1 c5t] (1 #cj-cc994 ,wet batt]y1 #bjd-bje994 ,:ite1 a comb9ation ( all colors1 #afb4 ,w9ds1 cause (1 #bj-ba4 ,w9t]1 reason = cold 91 #abg-abh4 ,wir+ = arc lamps1 #bcf-bci4 ,wood1 poor conductor ( heat1 #aah2 c>bon & hydrog5 91 #cae4 ,y>d/ick1 exp]im5t )1 to %[ lev]age1 #ei99-fj4 ,yea/1 action (1 9 bread mak+1 #cfe4 ,yell[1 9 flames1 #cah4 ,y]kes ,obs]vatory1 telescope (1 #aef994 ,z9c1 9 electric batt]y1 #bjc-bjf2 an elem5t1 #cjj2 us$ = driv+ hydrog5 out ( acid1 #cja1 #cjd4 99 99 99 99 99 ,,cons]vation ,,s]ies ,illu/ration ,cons]vation ,read] ,by ,,h>old ,w4 ,,fairbanks1 ,ph4 ,d4 ,lectur]1 ,univ]sity ( ,cali=nia2 ,geography ,sup]visor ,b]keley ,public ,s*ools ,a small book br++ out 9 a simple & int]e/+ mann] ! pr9ciples ( cons]vation ( natural res\rces has long be5 want$1 or !re has be5 little on ! subject t c\ld be plac$ 9 ! h&s ( pupils4 ,x is to answ] ?is ne$ t ,fairbanks' ,,cons]vation ,,read] has be5 prep>$4 ,! book t\*es ^u e phase ( cons]vation1 b x deals at greate/ l5g? ) sav+ ! soil1 ! =e/s1 & wild life4 ,x is "o ( ! au?or's ma9 purposes to ar\se a /rong] s5tim5t = pres]v+ :at rema9s ( ! =e/s z well z = ext5d+ _! areas4 ,?is is because prop] =e/ation w less5 ! dang] ( floods & ( erosion ( ! soil1 & x w enc\rage ! return ( ! wild creatures t are ( s mu* economic importance & add s mu* to ! joy ( life4 ,! matt] is pres5t$ 9 an easy n>rative /yle t is calculat$ to ar\se ! intellig5t int]e/ ( *ildr54 ,! text is illu/rat$ ) photographs ( wild animals1 trees1 l&scapes1 & r>ely beautiful birds1 pr9t$ 9 colors4 ,! subject is timely & ! treatm5t is happy ?r\gh\t4 ,,cons]vation ,,read] %\ld be us$ z a read] or z a book = regul> /udy 9 e elem5t>y s*ool 9 ! c\ntry4 ,clo?1 vi #baf pages4 ,price #a4dj4 ,,_w ,,book ,,company ,,yonk]s-,,on-,,hudson1 ,,new ,,york #babf ,,prairie ,,av5ue1 ,,*icago ,illu/ration 99 99 99 99 99 ,,indian ,,life ,,& ,,indian ,,lore ,,indian ,,days ,,( ,,! ,,long ,,ago ,,9 ,,! ,,l& ,,( ,,! ,,head-,,hunt]s ,,two ,,books ,,= ,,"y ,,p ,,by ,,edw>d ,s4 ,,curtis ,au?or ( ,! ,nor? ,am]ican ,indian ,9 ,indian ,days ( ,! ,long ,ago ! au?or gives an intimate view ( ,indian life 9 ! old5 days1 reveals ! great div]sity ( language1 dress1 & habits among !m1 & %[s h[ e important act ( _! lives 0 influ5c$ by spiritual beliefs & practices4 ,! book tells ! /ory ( ,kuksim1 an ,indian lad :o is eag]ly await+ ! "t :5 he %all be a w>rior4 ,x is full ( my?ical lore & ?rill+ adv5tures1 culm9at+ 9 ! m\nta9 vigil1 :5 ,kuksim he>s ! _s voices :i* m>k ! pass+ ( 8 *ildhood4 ,illu/rat$ ) photographs by ! au?or & draw+s by ,f4 ,n4 ,wilson4 99 99 99 99 99 ,!odore ,roosevelt once said t ,mr4 ,curtis has caught glimpses1 su* z few :ite m5 ev] cat*1 into ! /range spiritual & m5tal life ( ! ,indians4 ,9 ,9 ! ,l& ( ! ,head-,hunt]s ^! glimpses are %>$ ) 8 read]s4 ,! /ory c5t]s ab\t ,motana1 ! son ( ! great ,w> ,*ief4 ,! m\nta9 vigil1 ! woo+ & w9n+ ( ,naida1 ! raid ( ,yaklus & 8 w>riors1 ! rescue ( ! captur$ ,naida1 & ! f9al victory1 celebrat$ by c]emonial dances1 are all describ$4 ,! action is rapid & ! /ory is told 9 ! direct1 simple /yle ( ! true epic4 ,illu/rat$ ) ?irty full-page photographs by ! au?or4 ,price #a4fj ea*4 ,,_w ,,book ,,company ,,yonk]s-,,on-,,hudson1 ,,new ,,york #babf ,,prairie ,,av5ue1 ,,*icago ,illu/ration 99 99 99 99 99 ,,insect ,,adv5tures ,by ,j4 ,,h5ri ,,fabre ,select$ & ,arrang$ = ,"y ,p by ,l\is ,seym\r ,hasbr\ck ,illu/ration ,a new supplem5t>y read] 9 nature /udy = ! int]m$iate grades4 ,a book conta9+ a va/ am\nt ( in=mation relat+ to insect life--! life /ory ( ! spid]1 ! fly1 ! bee1 ! wasp1 & o!r insects--told by "o :o 0 at once a lov] ( nature1 a great sci5ti/1 & a mo/ ent]ta9+ writ]4 ,maet]l9ck calls ,fabre ! insects' ,hom]1 & decl>es t 8 "w is z mu* a classic z ! fam\s ,greek epic1 & des]ves to be kn[n & /udi$ z a classic4 ,?is is ! fir/ "t t ,fabre's writ+s h be5 made available = s*ool use1 & ! book w prove a delight to s*ool *ildr5 :]ev] !y are giv5 ! *ance to read x4 ,no live boy or girl c\ld fail to be int]e/$ 9 nature subjects pres5t$ by s gift$ a naturali/ z ,fabre 9 ! =m ( su* absorb+ adv5tures4 ,! _m qua9t sket*es ) :i* ! book has be5 illu/rat$ by ,elias ,goldb]g complete its *>m4 ,a useful index is includ$4 ,clo?4 #cjj pages4 ,price #a4dh4 ,,_w ,,book ,,company ,,yonk]s-,,on-,,hudson1 ,,new ,,york #babf ,,prairie ,,av5ue1 ,,*icago 99 99 99 99 99 ,,new-,,_w ,,sci5ce ,,s]ies ,edit$ by ,john ,w4 ,rit*ie ,,trees1 ,,/>s & ,,birds ,a ,,book ,,( ,,outdoor ,,sci5ce ,by ,,edw9 ,,l9coln ,,moseley ,head ( ! ,sci5ce ,dep>tm5t1 ,/ate ,normal ,college ( ,nor?we/]n ,ohio ,! usefulness ( nature /udy 9 ! s*ools has be5 s]i\sly limit$ by ! lack ( a suitable textbook4 ,x is to meet ?is ne$ t ,trees1 ,/>s1 & ,birds is issu$4 ,! au?or is "o ( ! mo/ successful tea*]s ( outdoor sci5ce 9 ?is c\ntry4 ,he believes 9 field excursions1 & 8 text is design$ to help tea*]s & pupils 9 ! inquiries t !y w make = !mselves4 ,! text deals ) ?ree phases ( outdoor sci5ce t h a p]5nial int]e/1 & x w make ! b5efit ( ! au?or's long & successful exp]i5ce available to y\ng] tea*]s4 ,! fir/ section deals ) trees1 & ! discussion ( maples is typical3 ! /ud5t is rem9d$ t he has eat5 maple sug>2 !re is an int]e/+ acc\nt ( its production2 ! fact is br\ght out t ! sug> is really made 9 ! leaves4 ,! />s & planets t all %\ld "k are told ab\t simply & cle>ly4 ,! birds commonly met ) are consid]$1 & _! habits ( fe$+ & ne/+ are describ$4 ,p]t95t que/ions are scatt]$ ?r\gh\t ea* section4 ,! book is illu/rat$ ) #afg photographs1 #fi draw+s1 #i /> maps1 & ) #af color plates ( #eh birds1 f pa9t+s by ,l\is ,agassiz ,fu]tes4 ,x is well adapt$ = use 9 junior high s*ools1 yet ! pres5tation is simple en\gh = pupils 9 ! six? grade4 ,clo?4 viii #djd xvi pages4 ,price #a4hj4 ,,_w ,,book ,,company ,,yonk]s-,,on-,,hudson1 ,,new ,,york #babf ,,prairie ,,av5ue1 ,,*icago 99 99 99 99 99 ,,new-,,_w ,,sci5ce ,,s]ies ,edit$ by ,john ,w4 ,rit*ie ,,sci5ce = ,,beg9n]s ,by ,,delos ,,fall ,pr(essor ( ,*emi/ry1 ,albion ,college ,to supply ! ne$ = a c\rse t w give ! prep>atory tra9+ :i* any sci5tific /udy dem&s1 ,,sci5ce ,,= ,,beg9n]s by ,pr(essor ,delos ,fall 0 made4 ,! aim 9 ?is text is to w9 ! int]e/ ( pupils1 to give !m conceptions ( nature t are fundam5tal1 & above all to gr\nd !m 9 ! me?od ( sci5ce4 ,! subject matt] has to d ) ! e>? sci5ces1 & pr9cipally ) physics & *emi/ry4 ,9 ! developm5t ( ea* topic1 e advantage t ! pupils' exp]i5ce & int]e/ may af=d is utiliz$4 ,ex]cises or exp]im5ts are int]sp]s$ ?r\gh\t ! "w1 & = ^! only ! simple/ mat]ials are requir$4 ,! /udies are c>ri$ to ^? connect+ pr9ciples :i* p]mit ! organization ( k4 ,! book is illu/rat$ ) a numb] ( excell5t photographs & ov] #bjj draw+s ( m ?an usual m]it4 ,! text is adapt$ = use 9 grades sev51 eight1 & n9e1 or 9 any classes t are ab\t to take up _! fir/ "w 9 sci5ce4 ,x w prove helpful to ! tea*]s & pupils :o use x directly1 & its influ5ce w cont9ue ) classes z !y advance4 ,x w ?or\ghly gr\nd pupils 9 ^? ideas t are pr]equisite to any "r "w 9 sci5ce4 xi #chh pages4 ,price #a4fh ,,_w ,,book ,,company ,,yonk]s-,,on-,,hudson1 ,,new ,,york #babf ,,prairie ,,av5ue1 ,,*icago 99 99 99 99 99 ,,new-,,_w ,,sci5ce ,,s]ies ,edit$ by ,,john ,w4 ,,rit*ie ,! publication ( books t apply ! _w's k to ! _w's ne$s is ! ideal ( ?is h\se & x is int5d$ t ! diff]5t volumes ( ?is s]ies %all express ?is ideal 9 a v concrete way4 ,complet$ ,,human ,,physiology4 ,by ,john ,w4 ,rit*ie1 ,pr(essor ( ,biology1 ,college ( ,william & ,m>y4 ,a text on physiology1 hygi5e1 & sanitation = upp] gramm> or junior high s*ools4 #a4fj4 ,,laboratory ,,manual ,,= ,,human ,,physiology4 ,by ,c>l ,h>tman1 ,univ]sity ( ,texas4 ,a manual to accompany ,rit*ie's ,human ,physiology4 ,,b\nd ,,9 ,,pap] ,,& ,,clo?4 #fj c5ts & #a4jj4 ,,sci5ce ,,= ,,beg9n]s4 ,by ,delos ,fall1 ,albion ,college1 ,mi*igan4 ,a beg9n+ text 9 g5]al sci5ce = int]m$iate s*ools & junior high s*ools4 #a4fh4 ,,ex]cise ,,& ,,review ,,book ,,9 ,,biology4 ,by ,j4 ,g4 ,blaisdell1 ,yonk]s1 ,n4 ,y41 ,high ,s*ool4 ,a comb9$ laboratory guide1 notebook & review book = /ud5ts' use4 ,writt5 f ! /&po9t ( effici5cy & furni%+ mat]ial = a ye>'s "w & to accompany any "o ( sev]al high-s*ool texts 9 g5]al biology4 ,,b\nd ,,9 ,,/rong ,,pap]4 #a4bj4 ,,trees1 ,,/>s1 ,,& ,,birds4 ,by ,e4 ,l4 ,moseley1 ,ohio ,/ate ,normal ,college1 ,b[l+ ,gre54 ,a book ( outdoor sci5ce = junior high s*ools & ! upp] gramm> grades4 #a4hj4 ,,p]sonal ,,hygi5e ,,& ,,home ,,nurs+4 ,by ,l\isa ,c4 ,lippitt1 ,univ]sity ( ,wiscons94 ,a practical text = use ) classes ( "y wom5 9 vocational & indu/rial high s*ools1 colleges1 & normal s*ools4 #a4fh4 ,,sci5ce ,,( ,,plant ,,life4 ,by ,e4 ,n4 ,transeau1 ,ohio ,/ate ,univ]sity4 ,a sci5tific & v practical text = high s*ools4 #a4hh4 ,,zo,,logy4 ,by ,t4 ,d4 ,a4 ,cock]ell1 ,univ]sity ( ,colorado4 ,a text = college use4 #c4fj4 ,,exp]im5tal ,,organic ,,*emi/ry4 ,by ,a4 ,p4 ,we/1 ,univ]sity ( ! ,philipp9es4 ,a text = college use4 #c4bj4 ,,common ,,sci5ce4 ,by ,c>leton ,w4 ,wa%burne1 ,sup]9t5d5t ( ,s*ools1 ,w9netka1 ,ill9ois4 ,especially made = junior high s*ools4 #a4fh4 ,also ,manual = above1 #bj c5ts4 ,o!r volumes are also 9 prep>ation4 ,,_w ,,book ,,company ,,yonk]s-,,on-,,hudson1 ,,new ,,york #babf ,,prairie ,,av5ue1 ,,*icago 99 99 99 99 99 ,,indian ,,life ,,& ,,indian ,,lore ,,! ,,h]o ,,( ,,! ,,longh\se ,by ,,m>y ,e4 ,,la+ ,illu/rations f #bg pa9t+s by ,david ,c4 ,li?g[ ,?is /ory gives a portrayal ( ! noble/ ( ,indians--,hiawa?a4 ,x foll[s e/abli%$ facts1 & b>es to ! read] ! he>t ( 8 race4 ,x is a conv9c+ tale4 ,! tra9+ ( ! ,indian y\? is %[n2 ! c>e] ( ! h]o z a w>rior is told2 8 great "w = peace ) ! ,five ,tribes is describ$4 ,besides ! /ory1 !re is an acc\nt ( ! hi/orical ,hiawa?a2 also a complete ,gloss>y giv+ def9itions z well z pronunciations ( ! new ,indian words4 ,a map ( ! c\ntry ( ! ,longh\se w enable ! read] to foll[ ! j\rneys ( ! ,indian p4 ,! book is int5d$ z a supplem5t>y read] 9 s*ools1 be+ adapt$ to ! six? grade or above4 ,x w also be valuable 9 gr\ps ( ! ,wood-craft ,league1 ,camp-fire ,girls1 & ,boy ,sc\ts4 ,clo?1 xxvi #cbi pages4 ,price #a4fj4 ,,_w ,,book ,,company ,,yonk]s-,,on-,,hudson1 ,,new ,,york #babf ,,prairie ,,av5ue1 ,,*icago 99 99 99 99 99 ,illu/ration ,,regi/]$ ,,trade ,,m>k ,,*emcraft ,,! ,,*emical ,,outfit ,makes ,y an ,amateur ,*emi/6 ,y c p]=m a great _m useful & practical *emical exp]im5ts1 h a lot ( fun1 & le>n ! pr9ciples ( *emi/ry1 if y h a ,,*emcraft outfit4 ,& an outfit n[ w help y 9 *emi/ry lat] on4 ,ea* ,,*emcraft outfit is a complete *emical laboratory conta9+ _m h>mless *emicals1 all ne$$ app>atus1 & a ,manual ( ,in/ruction giv+ accurate in=mation on ! subject4 ,,*emcraft is real *emi/ry4 ,^! outfits are n[ us$ by _m s*ools & are endors$ by pr(essors & tea*]s4 ,y c *oose y\r outfit f ,,five ,,sizes,,no4 #j--ge;,c4 ,,no4 #a--a4ej4 ,,no4 #b--b4ej4 ,,no4 #c--e4jj4 ,,no4 #d--aj4jj 7,we/ ( ,d5v]1 ,colo41 #aj additional7 ,sold by mo/ toy /ores & 9 any toy dep>tm5ts4 ,if n obta9able ne> y\r home1 any outfit w be deliv]$ f ! factory at ! price li/$4 ,m complete descriptions w be s5t ,free to any boy or girl1 or s*ool au?ority1 ^u reque/4 ,,! ,,port] ,,*emical ,,company ,port] ,products ,put ,sci5ce at ,y\r ,s]vice ,,hag]/[n--,,m>yl& 99 99 99 99 99 ,illu/ration ,! ,bigge/ ,?+ ( its k9d 9 ! ,_w ,,calumet ,,bak+ ,,p[d] ,x may be int]e/+ to "k :i* is ! l>ge/ city 9 ,*9a--! l>ge/ riv] 9 ,africa--b x is ,,m important to "k ab\t ! indu/rial life ( y\r c\ntry--because :5 mo/ ( y g out into ! _w y w become active figures 9 ! mak+1 buy+ & sell+ ( ?+s4 ,! ,calumet ,bak+ ,p[d] factories1 9 ,*icago & ,ea/ ,/4 ,l\is are ! l>ge/1 mo/ mod]n & sanit>y plants ( _! k9d on e>?4 ,m p\nds ( ,calumet are sold ?an ( any o!r br& ( bak+ p[d]4 ,t is because ,calumet is ! be/ pure/1 mo/ dep5dable bak+ p[d] made2 makes ! f9e/1 mo/ :olesome1 ta/y pies1 cakes1 biscuits1 d\ghnuts1 etc4 ,y w f9d ! same rule applies to ev]y?+ y d 9 life4 ,if y d a ?+ bett] ?an any "o else--y\r s]vices w always be 9 dem& & y w surely be a lead] 9 y\r l9e ( "w4 ,calumet ,bak+ ,p[d] is sold at a mod]ate price--has m ?an ! usual leav5+ /r5g?--& ,,nev] fails4 ,a slip 9 p\nd c tells h[ to get ! beautifully illu/rat$ ,calumet ,cook ,book4 99 99 99 99 99 ,,v5us ,,p5cils ,! l>ge/ sell+ ,,quality p5cil 9 ! _w ,illu/ration ,z s(t z y wi%2 z h>d z y please2 b always smoo!r ?an y _h dream$4 ,any ,v5us ,p5cil y select glides ov] ! pap] ) a re/ful fre$om f friction4 #ag ,,black ,,degrees1 #c ,,copy+ ,= bold1 heavy l9es #f;,b-#e;,b-#d;,b-#c;,b ,= writ+ sket*+ #b;,b-,b-,,hb-,f-,h ,= clean f9e l9es #b;,h-#c;,h-#d;,h-#e;,h-#f;,h ,= delicate1 ?9 l9es #g;,h-#h;,h-#i;,h ,,pla9 ,,ends1 ,,p] ,,doz4 #a4jj ,,rubb] ,,ends1 ,,p] ,,doz4 #a4bj ,,v5us ,,eras]s #ab ,,sizes ,illu/ration ,( ! same sup]b quality z ! ,v5us ,p5cil ,s5d = free sample4 ,at all ,/ation]s & ,/ores ,am]ican ,lead ,p5cil ,co4 #bbj ,fif? ,ave41 ,n4 ,y4 & ,london1 ,eng4 99 99 99 99 99 ,transcrib]'s ,notes3 page #bch3 *ang$ diagram$ to diagramm$ 7,z !re diagramm$1 ! electricity passes out4447 page #bec3 ! ,morse telegraph code is z 9 ! orig9al2 ?is is n ! mod]n ,int]national ,morse code ,page #dab1 *ang$ conrcete to concrete 7444 %all express ?is ideal 9 a v concrete way47 ,g5]al3 v>iable spell+ ( iod9_/iod9e 9 ! orig9al has be5 pres]v$ ,g5]al3 spell+ ( dioxid & *lorid 9 ! orig9al has be5 pres]v$