Oct., 1936
E. M.
F. OF THE CELLZn-Hg, ZnSO4, PbSO4, Pb-Hg
It is striking that the molar increment of surface tension of the hydrochloride or sodium salt of e-aminocaproic acid is very much less negative than that of isoelectric a-aminocaproic acid and therefore Q f o r t i o r i presumably less negative than that of its salts. This is an illustration of the fact pointed out by Cohn6on the basis of a systematic study of solubilities that the effect of a CH2 group situated between polar groups (whether or not they bear a free charge) is different from that of one located in a hydrocarbon residue in the molecule. As a result of the application of a new and exceedingly accurate method of measuring surface tension Jones and Ray19report a very curious phenomenon shown by aqueous solutions of inorganic salts. The surface tension-concentration curves, which are linear at ordinary concentrations, do not continue straight back to the ordinate axis, but dip down so as to show negative surface tension increments when the solutions are very dilute. It (19) Jones and Ray, TRISJOURNAL, 67, 957 (1935).
1855
would be of importance in any theoretical interpretation of surface tension to know whether or not dipolar ions behave in the same way, and it is hoped in the future to study the problem by this more accurate method.
Summary Measurements of the surface tension of aqueous solutions of seven amino acids of differing size and moment and of glycine betaine have been made with the drop weight method. In the case of four of the amino acids the surface tension is greater than that of water; in the other cases it is less. In these dipolar ions there appears to be an antagonism between the effect of the electric moment which tends to increase the surface tension, and the size and number of organic groups in the molecule which tend to lower it. The effect of converting an amino acid into its hydrochloride or its sodium salt is to lower the surface tension of the solution. CAMBRIDGE, MASS. RECEIVED JULY 10, 1936
I
The Electromotive Force of the Cell Zn-Hg (2 phase) ZnSO, (m)PbS04 (s) 1 Pb-Hg (2 phase) and its Temperature Coefficient at 25' and Concentrations from 0.05 to 1.5 Molal' BY JACOB KIELLAND~ Determinations of the e. m. f . of the cell
amlysi reagents in the way recommended by
Bray3and stored under doubly distilled water until needed. Zinc sulfate stock solution was made up from Kahlbaum "zur analyse" reagents and corresponding to the chemical reaction Zn (satd. amalg.) + PbSO, (s) = ZnSO, (nt) Pb (satd. doubly distilled water, and analyzed by the zinc amalg.) (2) ammonium phosphate method as well as by weighing in the form of zinc sulfate after evaporation and have been reported by Bray3 a t 25' for molalities heating on addition of some drops of sulfuric acid. from 0,0005 to 3.5, and by Cowperthwaite and Four per cent. lead amalgam and 4% zinc La Mer4 a t 0, 12.5, 25, 37.5 and 50' for molalities amalgam were made up with pro anulysi metals from 0.0005 to 0.01, also 0.02 and 0.05 molal at and redistilled mercury as described by Cowper0,25 and 50'. thwaite and La Mer,4 filtered hot through capillary In the present paper are given some e. m. f. a slight excess pressure tubings and stored under measuremeiits on cell (1) for the molalities 0.0512, of purified nitrogen. 0.150, 0.510 and 1.501 a t the temperatures 15, 25 Tank nitrogen was purified from oxygen by the and 35'. wet combustion method described by Van Brunt,s Experimental Part using a nitrogen lift pump to circulate the amPreparation of Materials.-Lead sulfate of moniaammonium carbonate solution over the definite crystalline form was prepared from pro copper wire gauze filling of the absorption tower. (1) This work was aided by a grant from "Anna Paus's Legat." Experimental Method.-The cell was similar (2) Research Chemist, Norsk Hydro-Elektrisk Kvaelstofaktieselskab, Oslo. to that used by Cowperthwaite and La Mer,4with (3) U. B . Bray, TBISJOURNAL, 49, 2372 (1927). Zn-Hg (2 phase) 1 ZnSOc (m)PbSOd (s) I Pb-Hg (2 phase) (1)
+
(4) I . A . Cowperthwaite and V. K . La Mer, i b i d . , 6S, 4333 (1931).
( 8 ) C. Van Brunt, i b i d . , 56, 1448 (1914).
1856
JACOB
KZXELLAND
VOl. 68
the exception th@tthe electrodes were inserted at owing to the solubility of lead sulfate at the conthe top, using well ground glass joints. The solu- centrations stated in the present paper, are less tions and the cell were freed from oxygen by run- than 0.01 mv., and are tberefore not taken into ning purified nitrogen through the whole system account. for four hours. The method of filling the cell The values of the mean practical6 stoichiometwith amalgams and solutions, and sealing off with ric activity coefficient for zirlc sulfate, given by mercury, was essentially the same as used by the equation Cowperthwaite and La Mer. The cleaning of cells and electrodes was effected by washing with concentrated sulfuric acid, are collected in Table 11, using the best values for distilled water, and then with a weak alcoholic Eo obtained by Cowperthwaite and La Mer.4 solution of potassium hydroxide. They were TABLEI1 then rinsed ten times with doubly distilled water, MEAN PRACTICAL STOICHIOMETRIC ACTIVITY COEFFICIENTS steamed out for an hour and subsequently dried OF ZINC SULFATE at 110”. Molality, 1 = 15’ t = 25’ I 350 m (EO = 0.42155) (Eo 0.41086) (Eo = 0.3992) Constant e. m. f. was ordinarily obtained one 0.209 0.202 0.190 0.0512 to four hours after the cell was prepared, and was ,123 ,113 ,128 ,150 controlled by readings after fifteen to twenty ,510 ,0667 ,0631 .0569 hours. It was found that a constant potential ,0372 .0342 ,0392 1.501 was far more rapidly obtained by passing from Discussion higher to lower temperatures than vice versa, The agreement between the values presented Apparatus.-The measurements were carried out with an Otto Wolff Potentiometer 5881 and here and those given by the measurements of a Hartmann and Braun Reflecting Galvanometer Cowperthwaite and La Mer4 up to 0.05 molal is No. 1528. A Weston element calibrated by very good. The activity coefficients given previously by “Polytechnisches Reichsanstalt” served as the Braya are all higher than those found by Cowperstandard cell. The regulation of the thermostat thwaite and La Mer and by the present author. temperature was maintained to a precision of This discrepancy can be traced back to Bray’s ~ 0 . 0 2 ’by means of mercury regulators. measurements in the most dilute concentration Results range.’ Using Cowperthwaite and La Mer’s The observed values of e. m.f . (Eobsd) and of E&.I = 0.41086, which hitherto is the most reE”, computed from the equation liable value given for the normal potential of the Eo’= Eobsd. (vRT/nF) In V?. (3) cell (l), the activity coefficients given by Bray are given in Table I, The corrections necessary were recalculated. The results are shown in Table 111. TABLEI
-
-
+
OBSERVED E. M. F. AND COMPUTED VALUESOB Eo’ Molality, ffl
Eobad.
0,0612 .150
0.53425 .51955 .50551 ,49195
,510 1.501
(YRTIaF) In m
Temperature 15” -0.07278
-
+
,04710 ,01671 .01008
eo, 0.46047 .47245
0,52830 .51350 ,49915 .48500
0.0512 .150 ,610 1 501
0.52215 .50740 ,49285 .47800
-0.07635 ,04873 - .01729 f .01043
-
Temperature 35” -0.07891 - ,05037 - 01787 f ,01078
m y*
0.45195 .46477 ,48186 ,49543 0.44324 .45703 ,47498 .48878
0.477 0.08 0.1 0.182 0,148 1.0 1.5 0.0439 0.0368 y*
,48880 .50203
Temperature 25’ 0.0512 ,150 .510 1.501
TABLEI11 MEANPRACTICAL STOICHIOMETRIC ACTIVITY COEFFICIENTS OF Z I N C SLlLFATE AT 25”, RECALCULATED FROM BRAY’S MEASUREMENTS m 0.005 0.01 0.02 0.05
m y*
0,387 0.2 0.104 2.0 0.0354
0.298 0.3 0.0837 2.5 0.0368
0.202 0.5 0.8 0.0634 0.0491 3.0 3.5 0.0409 0.0476
(8) Cf.practicnl aud rationnl activitv coefficients by E:. A. Gusgmheim, Phil. Mag., 19, 588 (1935). (7) The uncertainty of Bray’s extrapolation was alrendy pointed out by Gronwall, La Mer and Sandved [ P h r s i k Z . , 29, 390 (1928)], who found a somewhat different value, with “a” = 4.0 A. Cowperthwpite and La Mer’s “a” = 3.64 is however the most reliable, since cryoscopic measurements also give “a” = 3.6. Bray’s measurements at the highest dilutions consequently should not be taken into account.
~,~~-DIHYDROPHENANTHRENE AND DERIVATIVES
Oct., 1936
1857
These recalculated coefficients are in good agreement with Cowperthwaite and La Mer’s at concentrations 0.005 to 0.05 na, and with the author’s at 0.05 to 1.5 m. Log T* us. fl are shown in Fig. 1. It would be of great interest to obtain values of the partial molal heat of dilution of zinc sulfate at concentrations here studied, on account of the difference between the calorimetric values given by Lange and collaborators8 and the results of La Mer and Cowperthwaite, obtained by appliBut cation of the Gibbs-Helmholtz e q ~ a t i o n . ~ in the case of zinc sulfate depends about as equally upon the precision with which (E’ Eo) and d ( R ’ - R ) / d T can be determined, it is ob0.5 1.0 1.5 vious that more than the three temperatures indrn. vestigated in the present paper, are necessary to Fig. 1.-Mean stoichiometric activity coeEcients obtain values of which are sufficiently accuratelo of zinc sulfate a t 25”: 0 , Measurements of Cowperto be compared with those determined calorimetthwaite and La Mer; B, Bray; A , Kielland. rically. The final answer to the questions must therefore await a more extended investigation.“ for Uorganisk Kjemi,” Trondheim, and espeAcknowledgments.-The author is indebted to cially to Docent K. Sandved, in whose laboratory “Norsk Hydro-Elektrisk Kvdstofaktieselskab,” this work has been done. summary Oslo, to “Norges Tekniske Hoiskole, Institutt (8) E. Lange, J . Monheim and A. L. Robinson, THIS JOURNAL, 56, The electromotive force of the cell Zn (satd. 4733 (1933). (9) V. K.La Mer and I. A Cowperthwaite, ibid., 66, 1004 (1933). amalgam) ZnSOa(m), PbSOd(s) Pb (satd. amal(10) The partial molal heat of dilution varies considerably with gam) has been measured a t 15, 25 and 35’ for the temperature, according t o some unpublished calculations of en - c: for zinc sulfate a t concentrations studied; hence i t is neces- concentrations of zinc sulfate of 0.0512, 0.150, sary to make use of a sufficient number of temperatures. 0.510 and 1.501 molal. The activity coefficients (11) According to a communication from Professor La Mer, of zinc sulfate are given for these concentrations W. H. Wood, working with Dr. Cowperthwaite, has been reinvestitemperature intervals from 0 to gating the e. m. f. of the cell a t and temperatures. 50’ from high dilution to one molal, the results have not yet been
z2
-
zz
I
I
5 O
OSLO,NORWAY
published.
[CONTRIBUTION FROM THE COBB CHEMICAL
LABORATORY, UNIVERSITY
RECEIVED JUNE 2, 1936
OF VIRGINIA)
Studies in the Phenanthrene Series. XIII. 9,lO-Dihydrophenanthene and Amino Alcohols Derived from It1T2 BY ALFREDBURGERAND ERICHMOSETTIG The important investigations of Schroeter and phenanthrene, 1,2,3,4-tetrahydrophenanthrene his co-workers3 have shown that phenanthrene and 1,2,3,4.,5,6,7,8-octahydrophenanthrene, in yields by catalytic hydrogenation (elevated tem- amounts which depend upon the mode of reperature and pressure) and by reduction with duction. These investigators determined the sodium and amyl alcohol, three well-defined structure of the hydrocarbons beyond any doubt hydrogenation products, namely, 9,10-dihydro- by synthetic methods, thus ridding the literature (1) The work reported in this paper is part of a unification of of the great confusion prevailing in the Series Of effort by a number of agencies having responsibility for the solution hydrogenated phenanthrenes to that time‘ of the problem of drug addiction. The organizations taking part are‘ The Rockefeller Foundation, the National Research Council, the While the octahydro4 and tetrahydro compounds U. S Public Health Service, t h e U. S. Bureau of Narcotics, the may be isolated quite conveniently from the University of Virginia and the University of Michigan (2) See preliminary note, THIS JOURNAL, 57, 2731 (1935). (3) Schroeter, Ber , 5 7 , 2 0 2 5 (1’124), Schroeter, MWer and Huang,
ibrd , 62, 645 (1q20)
(4) For a convenient preparative method of octahydrophenanthrene, see \ a n de Ramp and Mosettig, THIS J O U R N A L , 67, 1107 (lY35).
