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iiidcpondonf ol" tlu^ slmpo oC llic ncsscI aiid (lic |»r()|K'rli('s of tlie 

 walls ill whicli ilic phase is enclosed. ImiI on die oMii'i- liand it 

 wan-anls also diat wc niav lind die (|naiiniv /' hv calcnlaUnL: die 

 pi-essiii-e w hicli would l>e e.xereised aizaiiisl a plane wall il' die 



niokcules did nol allracl one anollier, or liv addijii;- lo die prcs- 



sure exercised liv inuliiallv allrachnu- inolecnl(\s a.uainsl a plane wall. 



The wav in which ihe \ irial ol" die forces exciilnadnu in iniilnal 

 collisions of die inolecides has heen inlrodnced hij Prof. \ \\ dki; 

 A\ \Ai,s is as follows. \Vc assiiine dial in lirsi approxinialion I* 

 represenis also die pressure exeivised on die dislance spheres ol iIm- 

 iiiolccides. This would vield llie \aliie '1 Ph j. for die \irial. We 

 Jiiiisl. hoN\('\ei', lake oidv half Ihis \aliie. else all die forces would 

 lia\(' heen coiinled Iwice. 



TIk' dislance s|)lieres, howcxor, caiinol he considered as iinnio\in,u" 

 solid walls, hill as moxiiiii- and nio\ahle walls and Ihereldre il is 

 ptM'haps nol (jiiile snperlliions lo sho\\ expresslv dial llie\- are indeed 

 siihj(>cle(| lo a pressure anioimlinu' in lirsl <ip|.ro\iiiialioii on a\'era,ii'c 

 1<> l\ I N\ ill ,uivc flic proof of diis proposiiion in § I of ihis com- 

 ininiicalion. 



Ihe inlrodnclioii ol die correction leriii , ^ is hased onlhecon- 



sideralion thai the \alne of die \ irial L:i\'en al»o\'e will he too ureal 

 hecanse sonic of the distance spheres parllv coincide. The pai'ls of 

 tli(> siii-fac(> of a distance sphe/e 1 fallin.u' within a distance sphere 1 1 

 are [H'otected fnnii collisions with all oilier inolecides hnt II. There- 

 fore the pressure u\\ such parts is assnnied to he /,ero: on iIicoIIkm- 

 parts the pressure on die distance spheres is supposed |o he l\ This 

 comes to the same as the assiimplion that die axcraue |iressnre 

 diirinu' a time t (and ex'erv pressure \\ liicli we consider, die pressin-e 

 /''also, cannot he anvlhinu' else hiii an axorauc \aliie diirin.u' a certain 

 lime T) exerc-ised on an eieineiil do of a distance s|)liere would 

 he smaller than /'. hecanse of the fad dial the elemeiil 'A' is oiiI\ 

 dnrinii' a |»arl ol tli<' lime r exposed to die pressure /'. diiriiiü' ano- 

 ther part of that lime. howcNcr. il would liaxo heen snhjecled to no 

 pressiH'e. hecaiise it w a^ prolecled hv die dislance sphere of a mole- 

 cule II from collisions with oilier inolecides. 



I liaxc Iwo ohjectioiis lo the calcidalioiis ha>ed on lliese considerations. 



In the first place the assiimplion is made, dial a pari of a dishiiice 

 s[»liere would iiexcr experi(>iice aiiv pressure, when il lies wilhiii 

 die dislance spher<' of anolher molecule. In faci die reverse is irne: 

 ill or<l<.M- dial a snrlacc elcnuMit should experii-nce a presMn-e. a 



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