I: Y CI..lKESCE: J,. SI'E.:TE.:K.';
Consider the eqiiatioii
P'
ill -~ j3 ~~-
72,
i n which
--- l l ,
P
is the niini1~t.rof qainiiiolecules of one coiistitut.iit ~--rriiiiiiiolecillt~.s oi t h e other conqtitueiit. j tlie \.apor-pressiire in tlie piire ,state i)t' that constitiieiit to 11-hich 1 1 ~rvfers;,A' the \xpor-prc.siirv o f t l i t a i l i t ' constitiieiit niter the other coiistitiieiit hns Iireii i i i i srtl v i t h it. TT'e shall considtr a iiiistiire of t w o liqiiid coi1,stititeiits i i i i i cillle in all proportioii.s, aiicl apply the above ecliiatioii to rletvrIiiiiie tlie moleciilar iveiglits of the liq~iidconstituents. lin\-:, onl!. to coiisider each constitiie~it qxiratelj-. cliaiigiiig 11, iii1-c I I / , > as each coiistitnent in turn becomes the constitiient to ~rliicli /3 and j' refer. T h i s idea is i n essence due to Serlist.' Viifortiinatelj- \ y e 1iar.e fen. data a\.nilal,le for this p i i r pose. tlie \-apor-pressiires of 1io111og:lt.neoi:sliciiiid iiiistiii-~s:irt geiierall!- gi\-en as the si1111 of tlie \-apor-pressiires of the colistitiients, the partial pressiires not heiiig givrii. 1,iiiebarger ha, iiiatle soiiie iii\.estigatio~is' in this direction n-liicli will aii.-?I do not see l i o ~\-e can belie\-e a i d accordingly I prefer to think that these cur\-es do iiot represent the true vapor-tensioiis of chlorofonii n.itli benzene and toluene. Tlic experiments setmi to ha1-e been v e q - carefully made I h e b a r g e r . so an!- error of obser\.ation I think we ma!- del!. consider out of the question. I do think, however, there are .se\-ernl chances for errors iii tlie method. One, poiiited out 11!, Lineharger hiinself, is the failure of Lapor in a rather conceiitrated state to beliave according to A\.ogadro’s law, In tlie ca,se of chloroform, indeed, Liiiebarger s h o m that its 1-apor-pressure
I
can come oiit 3 percent lon.ei- than the \.apor-prewire found b!, Iiegnaiilt. T h i s ~voiildl x f u l l y sufficient to esplaiii the apparent dissociation n-itli benzene aiitl toluene. -4notlier chance \vould he a clieiiiical reaction of clilorofonn producing siilistances varying froin CHCI?C,,H,to CH( C,H,,);\\-it11 benzene and similar conipoiiiicls n-itli toluene. These sii1istaiice.q reiiiaiiiiiix cliiefl?. in soliitioii \voiild diiiiiiiisli tlie vapor-pressure of the chloroform. If an?' of theiii volatilized, the chloriii in tlieiii n-oultl be caught of conrse ljy the calciiiiii o s i t l , h i t beiiig calcnlatetl to chloroform. too little woiiltl lie siilitractetl froin tlie total i w s in \veig-lit of the bulbs, and tlie difference lit.t\veeii die total ioss in weight of the biilhs atid the clilorofnrni volatilized being attributed to the lieiizeiie or toluene \-olatilizecl. a vapor-pr lire too high ~ v o u l t l he assianed to 1,eiizeue aiid toluene. Siiice imizeiie aiitl toliieiie do react \vitli c1iloroic;nii iii the pi-eseiice of alniiiiiiiiiii cliloritl, I see n o reasoii against assuiniiix that they react soiiiewliat \\-ithout aluiiiiniiiii cliloritl. Tlie c i i n ~for l ~ i i z e n eiii a mixture of chloroforiii \vith I~eiizene,aiici the c~ii-vefor toluene i n a illistiire of chloroform ivitli toliiene are also to in!- iiiiiid i m p < silile for accordiiig to thc.s;c c i i r \ w either tlie iiioleailar \veiglit of clilorof'oriii does not cliaiige 011 dilutioii. altlioiigli above tlie normal molecular weight, i ~ else r i t increases oil dilution. Anotiier possiliiliT!. is tliis, that tile inoicciilar iiiasses of henzerie and toliieiie i i i a saturated \.apor state at ordinary teiiiperatures are R little above tlie iioriiial. Coiiseriiieiitl!. if tlie noriiial value.; \yere nsed the \.npor-l)i-es.;-""es \voiiltl cciiiie o u t too liigli. See iiiethod of calculatioii u s d I>!- I4iiie1iai-ger.' Let 11s pass 011 to coiisitler CC14 lvitli C,Hr, CCI, nit11 C-H.. and CCl, lvitli C,H.SO . L . CCI, arid C , H , ,(34.S? CClr 1)Ct IllOlS
c,11'
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IO
70
90 1
1. c .
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11,
CC1- , 169.4 I 3101 \\t CCli
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-7-7. -3 60.0
70
30 j0
1)Ct l l l ( J ! i V
30
,
109.6
10
I
I j5,8
153 1
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