The calculation s reporte d i n thi s paper appea r t o b e consisten t and accuratel y presented . However , I fai l t o se e th e purpos e behind Mr. Potter's paper . Ther e i s no apparent contributio n t o Thermodynamics, Engineerin g Science , o r Proces s Design . Th e scope i s tha t o f a ter m pape r fo r a graduat e thermodynamic s course and demonstrate s th e author's abilit y t o apply a n equatio n of state t o calculatio n o f a secondary thermodynami c function . The author' s

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... nclusio n that Joule-Thompso n coefficient s "ca n be compute d fro m eac h o f th e principl e sources o f equation s wit h equal confidence, " i s no t new . Th e literatur e ha s reporte d tha t equations o f state , representin g on e thermodynami c o r equilibrium paramete r well , ca n b e expecte d t o describ e other s wit h nearly equa l accuracy . Considerabl e effor t ha s gone into th e development o f th e equations o f state fo r stea m an d wate r reporte d in Mr . Potter' s reference s 6 , 7 , an d 9 . I a m surprise d tha t an y doubts woul d persis t tha t thes e relationship s ar e no t thoroughl y satisfactory base s fo r th e calculatio n o f thermodynami c properties. Further , reportin g Joule-Thompso n coefficient s t o fou r significant figure s goe s beyon d reasonabl e nee d o r interest . Th e percent deviation s reporte d i n Tabl e 8 , carrie d t o thre e decima l places, are irrelevant . The author's conclusio n tha t measurements o f Joule-Thompso n coefficients o f compressed liquid s are yet t o b e made i s quite valid . He ha s had t o go t o some length t o fin d a n experimenta l basi s fo r comparison wit h hi s calculations. I a m not sure tha t th e error i n conversion o f data fro m th e experiment cite d t o Joule-Thompso n coefficients i s equa l t o o r greate r tha n th e disagreemen t reporte d in Tabl e 8 . I not e tha t ther e i s n o referenc e t o th e possibl e us e of th e informatio n generated . I s i t perhap s tha t th e Joule -Thompson coefficien t o f compresse d liqui d i s o f n o practical valu e in design ? Thi s ma y hav e limite d generatio n o f laboratory dat a and literature . 1 woul d deligh t i n seein g a comprehensiv e pape r o n th e Joule -Thompson coefficien t o f th e condense d state . Thi s coul d b e a real contributio n t o th e thermodynami c literature . Th e presen t paper appear s to me to be a fragment withou t a purpose. Professor Potte r ha s presente d a n interestin g selectio n o f Joule-Thomson Coefficient s fo r compresse d liqui d wate r a s calculated fro m tw o genera l equation s o f state i n relation t o particula r experimental data . H e ha s show n i n Tabl e 7 tha t ther e i s remarkably littl e differenc e i n th e value s of . th e Joule-Thomso n coefficient obtaine d fro m th e Zaworsk i an d Keena n formulatio n and thos e obtained fro m eithe r th e Keyes, Keenan, Hill, and Moor e equation o r th e Meyer , McClintoc k an d Silvestr i equation , considering reasonabl e experimenta l uncertainties , particularl y i n regions where the Joule-Thomson coefficien t i s small. Considering tha t formulatio n o f th e singl e equatio n o f stat e was no t base d o n an3 r direc t experimenta l inpu t o f th e Joule -Thomson data , i t i s indee d gratifyin g tha t a degre e o f agreemen t between th e Joule-Thomso n calculate d i n thi s wa y an d als o tha t produced b y th e four-par t equatio n o f th e stat e o f Meyer , e t al . An interestin g compariso n o f dat a fro m th e Keena n e t al . equation wit h th e experimenta l dat a o f Harpe r show n i n Tabl e 8 . Here th e variation s d o no t see m t o sho w a simpl e patter n an d underline th e nee d fo r furthe r experimenta l dat a o n th e Joule -Thomson coefficient . It woul d b e o f valu e if , fro m hi s studies o f th e Joule-Thomso n coefficient i n th e supe r hea t regio n a s wel l a s th e compresse d liquid region , Professo r Potte r woul d provid e som e advic e o n where most attentio n i s needed experimentall y i n th e determination o f new values o f th e Joule-Thomson coefficient . Authors' Closur e The author s wis h t o than k Professor s Bhadur i an d Smetan a for thei r comment s o n thi s paper . I t shoul d hav e bee n note d i n the pape r tha t temperatur e measurement s hav e bee n mad e bot h upstream an d downstrea m o f th e tes t section . I n al l case s n o measurable temperatur e gradien t existed . Also , al l dat a ar e a t Reynolds numbers, pioh/jj., less than 35.0 . Th e minimum pressur e ratio acros s th e throttlin g valv e wa s 100 . Sinc e thi s i s fa r i n excess o f tha t neede d t o chok e th e flow i t i s apparent , tha t th e flow rate wa s indee d constant . A mor e detailed discussio n o f th e experimental procedur e has bee n give n by Wilkerson. 4 The author s believ e tha t th e question s raise d i n th e first fou r items o f Professo r Smetan a discussio n hav e bee n adequatel y answered i n previous publications [2 , 3, 4, 5 , 6]. Th e las t ite m i s worthy o f not e an d th e author s agre e tha t pressur e rati o i s a parameter o f importance . I n thi s pape r th e experimenta l dat a represents pressur e ratio s acros s th e tes t sectio n betwee n 6 6 an d 373. N o attemp t wa s mad e t o documen t pressur e rati o effect s beyond thi s limite d rang e wher e n o significan t effec t wa s noted . Future investigation s wil l conside r i n dept h th e pressur e rati o aspect.