0
25 MOLE
Fig. 3.--Phase
50 75 % ETHANE,
I00
diagram for l,%rli-( y-~yridyl)-cthatieand -ethylene.
of carbon tctrachloritlc w a s refluxed for 2 hours with 1.8 of S-broii~osucci~~iniitlc :inti 0.1 g. of l>enzoyl peroxide. The filtered hot solutioii. froin which spoiitaiicously upoii cooliiig, was hrought to tlryiiess. The residue, recrystallized froin ~ - h u t ~ i ofortncd I, silky needles of m.p. 265" (dec.). I t w d i the ~iioriohyrlrol~rotiiirle of I ,2tli-( y-pyridy1)-cthylciie. .InnZ. Calcd. for C121111S.Ilr:Iir. :30.4. Fouritl: Br, : N . Z (potentiometric titration 1. The h!drobroniiclc IV;I\ tritur;ttctl :I I rooin teinperature with an excess of aqucoii> ;itiirnoi~iai t n d the iiisoluble prodi i r ~filtered and recr!~st:tllized froin w t c r . M . p . ; t i i d niisetl i i i . 1 1 . with :ti1 authciitic ~;iiiipIeof 1 ,2-(1i-(-(-~)!.ritl!-l)-(.th!.lv i i v , lt55'. 1 ,Z-Di-(r-pyridyl )-ethane and Chloranil: -A solutiou \vas l)rqj:tred of 0.50 g . (2.46 niinole,s I of chloratiil i n 18 g. of h o t cc,
g.
benzene aiid 0.48 g. (2.46 mmoles) of the ethane iii 7 g. of dded. Immediately, ii brown-violet pre. After 2 hr. at room temperature, it \vas filtered, mashed with benzene and dried; yield 1.0 g . The substance has no defined melting point; it decomposc~ gradually above 250". The product peptizes in water; that the solution \vas colloidal was shown by the fact that atltlitioii of sodium or silver tiitrate caused coagulatioii. This 1)rrripitntc rctlispcrsed 011 \vashirig to remorc clcctrolytc A water dispersion of t h c iirotlurt \vas filtered :iiitI the filtrate w t s extracted with ether. The filtrate g:tve glistening Iilack crystals on evaporatioii uiider the aqpirator a t 50". 1'xr hoirtb wia1ysi.s gavc :edrwchillg thc heat of vaporizatioti of hexane when the mole ratio of hexane t o stearic acid is 0.*5. On dilute stearic acid rnonolar.crs the initial heat of sorption is high but falls rapidly and, after passing through a minimum rises t o approach the heat of vaporization when the surface is covered by a monolayer of hexane. On a clean water surface the hcat of sorption is not sig~iihcat~tlydifferetlt from t h c heat of wporization of n-hexane.
Very few iiieasureilients of adsorption have been made on plane surfaces where the area is known esactly rind there are e1.m fewer calculations o f the lieats of adsorption. Direct ineasurement of the cluantity adsorbed is difficult because adsorption iwrcly exceeds 10 gibhs (10 X IO--'" inole C I I I . " ~ " ) . The amount of a solute or vapor adsorbed on :I liqtiitl surface can he calculated froin the changes in , I) Prcsentrd a t 1Lr L:'l+t htrrtiiig of the A l n r r l c a n Chemical Sc) ciety, Colloid Division, Budalv, N. Y . , March, 1 9 2 buppurted 111 p a r t b y a grant from thc Frederick ( h r d n c r C < i t l r P l l Fund c > f t h ? I?csearch Corporation and in ],art b> i i yrtlnt irorn i h r S a t l r r o a l Inititute for Teurologicnl Diseases and Hlindne.;~ ( 2 ) Chemical Division, The Borden Co.,Rainhridge, 1 Y I? n. T k a n , .I. P l i ! , ~ Colloid ~ ' i w m, 6 5 , fil I I l ' ~ ~ ~ ~ 1 ' ~ 8.';)
surface tension with concentration by means oi tlw Gibbs equation. The calculation is straightforward for two component systems and I
