a rapid laboratory method of measuring the partial vapor pressures of

I 803

THE ELECTRO-TITRAMETRIC METHOD, ETC.

chlorine and phosphate in such liquids (for example, urine) no difficulties were presented, the results being in perfect accord with those obtained by the other methods. The advantages of the electro-titrametric method in these latter instances are, the possibility of an exact analysis of a few cubic centimeters, and a t the same time an extremely high degree of precision. It is necessary here to call attention to the fact that in the determination of SOc in such liquids certain complications were encountered, which impressed us with the fact that we had to deal with a liquid of different composition from the synthetical solution. Observing certain precautions, as for example, degree of acidity, kind of reagent, etc., we were in some instances able to obtain results which closely agreed with those of gravimetric determinations. The last curve is an illustration of the acid- and base-binding capacity of a physiological liquid, in this case urine. The previous statement in regard to the use of indicator is especially true in this case. It should not be overlooked, however, that the direction of the curve in such case6 is probably not entirely due to the above stated phenomena, because other factors, such as changing viscosity, may affect the total result. It is interesting to note that in this connection successive precipitations were observed after the addition of certain amounts of the reagent. It is the belief of the writers that such curves may prove to be in some cases a more instructive demonstration of the complex properties of such liquids and that more deductions might be drawn from such curves than those from a turning point of an indicator. As the nature of this publication is preliminary, the authors wish to reserve the right to develop this field more completely in the near future. AYHBRST,Mass.

[CONTRIBUTION FROM THE CHEMICAL LABORATORIES OF CLARKUNIVERSITY. J

A RAPID LABORATORY METHOD OF MEASURING THE PARTIAL VAPOR PRESSURES OF LIQUID MIXTURES. BY M. A. ROSANOFP. C.

W. BACONA N D R. H.WHITE.:

Received July 2, 1914.

Section 1.-Introductory Remarks. It is scarcely necessary to point out that the partial pressures of volatile mixtures are not measured as such. What is really determined, is the composition of the vapor which is in equilibrium with the liquid mixture. The partial pressures are then assumed to be proportional to the molar percentages of the components in the vapor, and their absolute values become known if the total pressures have been determined manometrically. I gladly acknowledge my indebtedness to my research assistant, Dr. John F. W. Schulze. for valuable help in preparing this paper for publication.

M. A . R.

I 804

M. A. ROSANOFF, C. W. BACON AND R. H. WHITE.

The main difficulty involved is that of analyzing the vapor with sufficient precision. The method that has been most extensively used in the past consists in distilling off a small amount from the given mixture and analyzing the distillate, on the assumption that if the relative amount of distillate is sufficiently small, its composition is w r y close to that of the first trace of vapor given off by the liquid. As the precision and reliability of this method are in many ways subject to dpubt, and as the results obtained have often been found to disagree with those yielded by other methods, it appeared desirable to devise a method, the reliability of whose results should, as far as possible, be free from doubt. Such, we believe, is the method devised by Rosanoff, Lamb, and Breithut,' and worked out in its practical details in these laboratories.2 It consists, briefly, in passing a binary vapor of constant composition through a liquid mixture of the same substances; as long as the liquid is not in equilibrium with the vapor, its composition changes, and consequently both its boiling point and the vapor escaping from it change continuously. When the composition of the liquid has finally adjusted itself to that of the vapor employed, and equilibrium has set in, everything becomes constant : the thermometerin the liquid indicates a constant temperature; the escaping vapor has ceased changing, and consecutive fractions of it condensed show the same composition. The attainment of equilibrium is thus attested in two independent ways, and as the condensed fractions can be taken as large as desired, the analytical difficulties disappear, and the composition of the equilibrium vapor becomes known with all precision necessary. Unfortunately, the required apparatus is somewhat complex, and its efficient handling calls for considerable manipulative skill, so that the method can scarcely be recommended for ordinary use, in connection with studies of either the theory of solutions or fractional distillation. The method just referred to has served to demonstrate that reliable partial pressure data can be obtained by distilling off a small fraction, as has long been practised. Thus, the well-known results obtained by v. Zawidzki3 are doubtless very good. Only, on account of the tendency of certain impurities, such as moisture, to accumulate in the first distillate, the organic liquids employed must be exquisitely purified, and the small distillate to be analyzed must be handled with great care, if its composition is not to be grossly affected by evaporation. Furthermore, even v. Zawidzki's apparatus is of somewhat complex construction and calls for no little delicacy of manipulation. Thus a need still remained for a simpler and more rapid, yet sufficiently reliable, laboratory method. 1 Rosanoff, Lamb, and Breithut, THIS JOURNAL, 31, 448 (1909); 2. physik. Chem., 66,349 (1909). 2 Rosanoff and Easley, THIS JOURNAL, 31, 953 (1909);2. physik. Chent., 68, 641 (1910). 3 Von Zawidzki, Z. physik. Chew, 35, r a g (1900).

PARTIAL VAPOR PRGSSURES OF LIQUID MIXTURES.

I 805

Such a method is described in the present communication. It was first devised and successfully employed in these laboratories during the year 1910-1911, and a brief preliminary account of it was published in 1911.~ Since then, however, it has been used here in a number of new cases of both binary and ternary mixtures, and to-day we feel justified in recommending it as the easiest method for ascertaining the composition of vapors in equilibrium with all sorts of liquid mixtures. We believe, further, that it would be especially useful where the available amount of substance is too small for the older methods to yield accurate results. Section 11.-Principle of the Method. The problem is to ascertain the composition of the first infinitesimal amount of vapor given off by a liquid mixture of known composition. To this end we subject the given mixture to distillation, carefully avoiding reflux condensation. The amount finally driven over may be as great as 80 or 90% of the total original weight. And imagine that we have , obtained knowledge of what the composition of the distillate was when its weight was, say, I g.; what the composition of the distillate was when its weight had reached 2 g., then 3 g., 4 g., 5 g., etc. If the composition of the distillates were now plotted against their weights, a curve would be obtained, every point of which would indicate the composition that the distillate would have when its weight has attained any definite amount within the range of the curve. But only a moderate extrapolation backward would lead up to the composition axis, that is, to where the weight of distillate is zero. The point of intersection would obviously indicate the composition of the first indefinitely small amount of distillate, and thus our problem would be solved. This is, in fact, our procedure. Only, instead of allowing the distillate to accumulate in the receiver, we remove seven or eight .consecutive fractions of it, and weigh and analyze them separately. Knowing the weights and compositions of Fractions I and 2, we can readily calculate the weight and composition that would have been found if they had been allowed to form a single combined fraction. Similarly, knowing the weights and compositions of I , 2 and 3, we can easily calculate what the weight and composition would have been if these three distillates had been allowed to form a single fraction, and so forth for the rest of the distillates obtained. The extrapolation just mentioned indicates, as stated, the composition of the first infinitesimal amount of vapor evolved by the given liquid mixture. But the same experiment yields also further information. Suppose that eight distillates have been collected and that the composition of the residue had been found by analysis. Knowing, again, the weights and compositions of Fractions 8 and 7, we can calculate the weight Rosanoff, J. Franklin Inst., 172,517 (1911).

I 806


and composition that would result if the two were mixed, or if they had been allowed to form a single fraction. Similarly, we can find the combined weight and composition of Nos. 8, 7 , and 6, then of Nos. 8, 7 , 6, and 5, etc. Suppose now that the weight of No. 8 is entered as an abscissa and the composition of No. 8 as the corresponding ordinate; that the combined weight of Nos. 8 and 7 is taken as a second abscissa, and their combined composition as a second ordinate, etc. A new curve would thus result, and this curve again we would extrapolate to intersection with the composition axis. The point on the curve corresponding to distillate No. 8 may be thought of as the composition of the mixture returned to the residue when the weight returned, as if by a reversal of the actual distillation, is that of No. 8. Similarly, the point of intersection on the composition axis would represent the composition of the first infinitesimal amount returned to the residue. But this is evidently nothing else than the composition of the slight amount of vapor still in contact with the residue. In this manner our one actual distillation teaches, not only what vapor is in equilibrium with the original mixture, but also what vapor is in equilibrium with the final residue. It would be easy to show that simple enough calculation could further reveal the composition of the vapors in equilibrium with mixtures intermediate between the original and the residue. But we will not insist on this point, as we have not made use of it in our practical work. Section 111.-Apparatus and Manipulation. In applying experimentally the simple principle just stated, an apparatus was devised in which reflux condensation is practically impossible. The apparatus, drawn to scale in cross section, is shown in Fig. I . It consists of a pear-shaped vessel with a long neck, near the upper end of which are four circular openings for the escape of the vapor. A glass jacket, fused on to the rim of the neck, surrounds the flask and ends below in a tube through which the vapors escape into a powerful worm condenser, and thence, in liquid rform, into a receiver having ‘several compartments for the convenient collection of consecutive fractions. The receiver communicates with the atmosphere through a tube filled with calcium chloride, to keep out moisture. The neck of the pearshaped boiling-vessel is permanently stoppered above with a cork, which is made thoroughly vapor- and liquid-tight with shellac and sealing-wax. The cork carries an electric heater of platinum wire, and, for the introduction and withdrawal of liquid, an adapter-tube reaching nearly to the bottom of the boiling-vessel. Liquid is introduced and withdrawn with the aid of a separatory-funnel fitted by means of a tight cork into the upper part of the adapter-tube, as shown in the diagram. During operation the boiling-vessel is thus surrounded by the vapor of the boiling liquid itself, and thus reflux condensation is prevented. But to make doubly sure

PARTIAL VAPOR PRESSURES OF LIQUID MIXTURES.

1807

of this, the jacketed distillation vessel is all but completely immersed in a bath, whose temperature, roughly constant, is somewhat above the highest temperature that may be attained by the boiling mixture experimented upon. The manipulation is very simple. A mixture of known composition is introduced into the distilling vessel and is set boiling by means of the electric heater. There being no reflux, the distillation is usually very rapid, each fraction taking only a minute or two to collect. The fractions are received in small, carefully weighed glass-stoppered bottles, and in scarcely half an hour, during which the apparatus requires little attention, the run is complete. Now a sample of the residue i s h t h drawn for analysis, the several distillates are weighed (with a precision of about 0.05 g.), and finally the residue and the distillates are analyzed as stated above. We have not mentioned the dimensions of the distillation apparatus. In our earlier work the pear-shaped boiler had a capacity of about 300 cc. and was almost filled with the liquid mixture for a run. To prevent the protrusion of the platinum heater above the liquid, the distillation was usually interrupted when about IOO cc. of liquid still remained in the vessel. More recently a smaller apparatus has been employed here, the pearshaped boiler having a capacity of only 125 cc., and the shape of the platinum heater was modified to permit of leaving a residue of barely 2 5 cc. There is, however, no reason why a still smaller apparatus should not be employed when only a scanty amount of experimental material is available.

1808


Section 1V.-Analytical Method. The composition of our binary mixtures was determined on the basis of their refractive indices by an interpolation method first recommended by Ostwald and since used by von Zawidzki and also in. this laboratory. The indices of a number of mixtures of exactly known composition are determined, and from these the percentages are calculated which would correspond to these indices if the latter obeyed the rule of additivity. The differences between the true and these "ideal" percentages are plotted as ordinates against the ideal percentages themselves. The resulting curve gives the correction to be algebraically added to the ideal percentage, the latter being calculated in any given case from the equation : Ioo(i - ia) Ideal percentage = ---%I--&

where il is the refractive index of the isolated component whose ideal percentage in the mixture is sought, iz is the index of the second component in the isolated state, and i is the observed index of the mixture. Tables 1-111 give the corrections for a number of ideal percentages in the case of three pairs of liquids; the data of Tables I and I1 are based on new measurements; the data of Table 111 are calculated from the measurements of von Zawidzki.' Corrections for other percentages than those given in the tables will readily be found by graphic interpolation. All these corrections lead to the true composition of the mixtures expressed in molar percentages. TABLE11. TABLEI. CKLOROFORM-TOLUENE. ACETONE-TOLUENE.

TABLE111.

ETHYLIODIDE-ETHYL

ACETATE. index of CHCla is The index of (CH&CO is The index of the iodide is 1.44301. That of C ~ H I C H ~ 1.35662. Thatof CsHsCH3 1.51009. That of the is 1.49337, Temp. 2 5 . 0 ~ . acetate is 1.37012. Temp. is 1.49323. Temp. 25.4'.

The

25.20. Ideal % ' CHCls. 0 IO

20

30 40

50 60 70 80 90 IO0

Correction.

Ideal yo Correc(CHs)nCO. tion.

0

.04 $3.72 $4.72 $5.26 $5.32 $5.04 f4.43 $3.31 + I .68 $2

0

0 IO

20

30

40 50

60 70 80 90 IO0

Von Zawidzki, LOC.cit., p. 145.

0

f3.03 f3.56 f7.35 +S .56 f9.16 $9. I2 $8.31 +6.52 $3.56 9

Ideal % CzHsI. 0 IO 20

30

40 50

60 70 80 90

!"

Correction. 0

$4.12 $6.96 $8.68 f9.4' $9.42 +S . 7 0 f6.21 $5.36 + 2 .96 9


I 809

Tables for the analysis of mixtures of carbon disulphide and carbon tetrachloride may be found in a former communication.' Ternary mixtures, whose partial pressures were determined by the present method, have been analyzed according to the procedure described by Schulze.2 Section V.-Purification of the Substances. Our substances were purified as follows: Carbon disulfide was thoroughly shaken with lime, allowed to stand for some time in contact with mercury, dried with calcium chloride, and distilled; a large middle fraction collected for use passed over within less than 0.I '. Kahlbaum's carbon tetrachloride required no further treatment than drying with calcium chloride and redistilling, the fraction collected for use boiling again within 0.I '. Chloroform from a well-known American manufacturer was washed with dilute sulfuric acid, then with caustic potash, and next, five times with water. After drying with calcium chloride, it was distilled in dim light, a large middle fraction, boiling between 60. g o and 6 1 .oo, being kept for use. A high-grade commercial toluene was thoroughly washed with water, dried with calcium chloride, and distilled, the utilized fraction passing over between 1 0 9 . 5 ' and 109.6'. A quantity of commercial acetone was boiled for ten hours with an excess of solid potassium permanganate, distilled off, dried with potassium carbonate, and redistilled; the fraction kept for use passed over within 0.I O. The ethyl iodide was prepared. by ourselves, from resublimed iodine, absolute alcohol, and pure red phosphorus; the crude product was washed with a solution of caustic potash and with water, then dried with calcium chloride, distilled, and preserved in contact with finely divided ("molecular") silver; the preparation distilled over completely between 7 2 . 6 ' and 7 2 , 8 '. Finally, a good grade of commercial ethyl acetate was washed with a 50% solution of calcium cgoride, then dried with fused calcium chloride, and distilled, the utilized fraction passing over between 76.6' and 7 6 . 7 '. Section VI.-Results

for Carbon Disulfide-Carbon

Tetrachloride.

TABLE1V.-RUN A. No. of distillate.

Weight of distillate. Grams. Index of refraction.

...................... ......................... 3 ......................... I...

2

. 4.........................

5 .........................

6......................... 7.........................

16.48 19.43 15.86 16.00 23.75 17.80 25.23

1 * 53177

I .53108 I .52815

1.52491 I . 52088 1.51639 I .SIX81

Molar % of CSI.

59.35 58.96 57.21 55.25

52.73 49.85 46.79

It would have been advantageous to express the composition of the disRosanoff and Easley, LOG.cit., p. 970.

* Schulze, "HIS JOURNAL, 36, 498 (1914).

1810


tiallates, not in molar, but in weight percentabes, as the former complicate the calculations unnecessarily. We will, however, reproduce all results in this paper in the form in which they were originally obtained and used. From the figures of Table IV, calculation gives the following: TABLE V. Distillates combined.

Cornbined weight Grams. 16.48 35.91 51.77 67.77 91.52 109.32 134.55

....................... ................... Nos. 1+2+3 ................ NOS. i + 2 + 3 + 4 ............. Nos. 1 + 2 + 3 + 4 + 5 . . ........ Nos. 1 + 2 + 3 + 4 + 5 + 6 ....... NO.

i

NOS. 1+2

Nos. 1 + 2 + 3 + 4 + 5 + 6 + 7 . .

..

Combined Combined compoCom- composition. bined sition. (Molar Distillatee weight. (Molar yo CSr.) combined. Grams. % CSI.) 59.35 NO. 7 25.23 46.79 59.11 NOS. 7+6 43.03 48.07 58.55 Nos. 7+6$5 ................ 66.78 49.76 57.79 NOS. 7 + 6 + 5 + 4 82.78 50.86 56.51 Nos. 7+6+5+4+3 98.64 51.92 55.47 Nos. 7$6+5+4+3+2 118.07 53.10 53.92 NOS. 7+6+5+4+3+2+1 .... 134.55 53.92

...................... ................... ............. .......... .......

The original mixture (refractive index = I .49780) contained 3 6 . 7 7 molar per cent Cs2. The third column of Table V shows, by graphic extrapolation, that the vapor in equilibrium with the original mixture contained 60.35 molar per cent Cs2. The residue (refractive index = 1.48000) contained 22.18 molar per cent CS2. The sixth column of Table V shows, by graphic extrapolation, that the vapor in equilibrium with the residue contained 44.85 molar per cent cs2.

The results of Table V are shown graphically by the pair of curves marked A in Fig. 2 . The curves, it will be seen, are very smooth, and the slight extrapolation introduces prartically no uncertainty. Only the first point on the upper curve, corresponding to the first distillate, fails to agree with the rest. The cause of this was doubtless a trace of moismixture contained in the original Fig. 2 .-Carbon~disulphide-carbon ture, and if one distillate only had been tetrachloride. examined, as is done in the older procedures, an error of a t least 1% would have been introduced, probably more. On the other hand, the shape of our curve and its extrapolation are scarcely rendered less certain by the irregularity of that one point.

181I

PARTIAL VAPOR PREsSURES OF LIQUID MIXTURES. TABLEVI.-RUN B. No. of distillate.

Weight of distillate. Grams.

......................... ..................... 3 . . ....................... 4 ......................... 5 ......................... 6 ......................... I

13.67

2...

18.01

Index of refraction.

Molar % of cs:.

1.55285 I ,55168 1 .549OI 1.54582 I .542OO I. 53890

70.78 70.19 68.80 67.14 65.08 63.43

16.22 21.43 12.14 17.76

TABLEVII. Distillates combined. No. 1

Combined Com- compoDistilbined sition. lates weight. (Molar comGrams. % CSz.) bined. 13.67 70.78 No. 6 ............. Nos. 6 f 5 31 68 70.44 49.90 69 89 NOS. 6 + 5 + 4 69.33 69.05 Nos. 6 + 5 + 4 + 81.47 68.48 NOS. 6 + 5 + 4 + . 99.23 67.60 Nos. 6+5+4 Original mixture (refractive index = 1. Corresponding vapor (by extrapolation 1.49889). . Residue (refractive index , , Corresponding vapor (by extrapolation

.......................

...

. .

-

Combined weight. Grams. 17.76 ......... 29.90

.......

.........

.. . . . .......

Combined compcsition. (Molar % C8.) 63.43 64.10

67.55 66.22 85.56 67.08

37.62% CS: 62.30% CS:

The results of Table VI1 are shown graphically by the pair of curves B in Fig. 2 . TABLEVIII.-RUN No. of distillate. I

z 3

.........................

......................... ..........................

4 ......................... 5 ......................... 6 .........................

Weight of distillate.

Grams.

C. Index of refraction.

18.25

I .56573

16.80

I .56465

16.66 14.37 14.50 15.54

1.56219 I ,56002 I ,55767 1.55486

Molar % of CSn.

77.28 76,57 75.37 74.33 73.20 71.81

TABLEIX. Combined Combined compocompoCombined sition. Combined sition. Distillates welght. (Molar Distillates weight. (Molar combined. Grams. % C s . ) combined. Grams. % CSn.) No. 1 ....................... 1825 77.28 No. 6 15.54 71 81 35.05 76.94 Nos. 1 + 2 . . Nos. 6+5 ................... 30.04 72.48 Nos. l f 2 S . 3 51.71 76.4% Nos. 6 + 5 + 4 ................ 44.41 73.09 6608 75.99 Nos. 1+2+3+4 Nos. 6 + 5 + 4 + 3 . . . . . . . . . . . . . 61.07 7372 Nos. 1+2+3$4+5 80.58 7S.49 77.87 74.34 Nos. 1$2+3+4+5+6 96.12 74.91 96.12 74.91 Original mixture (refractive index = 1.5 % cs2 Corresponding vwor (by extrapolation) % cs: Residue (refractive index = 1.51440). 48.52oJo CS? Corresponding vapor (by extrapolation). 70.90% CSZ

................. ................ ............. .......... ......

............

........................ .....................

The results of Table IX are shown graphically by the pair of curves C in Fig. 2.

1812

M. A. ROSANOFF, C. W. BACON AND R. H. WHITE. TABLEX.-RUN D. Weight of distillate. Grams.

No of distillate.

......................... 2 ......................... 3 .........................


15.94 15.02 17.54 16.86 14.66 16.87

I

4.........................

5 ......................... 6 .........................

yo of ‘2%. 80.88 80.62 79 * 86 78.93 78.02 76.88

Molar

1.57393 I .57336 1,57171 I .56966 1,56771 1 * 56534

TABLEXI. ComDistillates combined. No. 1. Nos. 1+2 Nos. 1 + 2 + 3 Nos. 1+2+3+4 . . . . . . . . . . . . . Nos. 1 + 2 + 3 + 4 + 5 . . Nos. 1 + 2 + 3 + 4 + 5 + 6 . .

...................... ................... ................

15.94 30.96 48.50 65.36 80.02 96.89

Combined weight. Grams. 16.87

No. 6 .................... Nos. 64-5.............. Nos. 6 + 5 + 4 ........... Nos. 6 + 5 + 4 + 3 Nos. 6+5+4+3+2 Nos. 6 + 5 + 4 + 3 + 2 + 1

80.88 80.73 80.43 80.05 79.68 79.20

.

Combined composition. (Molar %C%.) 76.88

48.39 77.96 78.46 78.87 79.20

........ . 65.93 ........ ..... . 80.95 ..... ......... 96.89 Original mixture (refractive index = 1.54167). ................ 64.94% CS: Corresponding vapor (by extrapolation). ... .. 81.22% CSl .. 55.82% CSY Residue (refractive index = 1.52583). ....... Corresponding vapor (by extrapolation).

.....................

76.13 % CSn

The results of Table XI are shown graphically by the pair of curves

D in Fig. 2 . TABLEXII.-RUN E. No. of distillate.

I......

...................

......................... 3 ......................... 4......................... 5. ....................... 6 . . . . ..................... 2



18,.09 18.28 21.23 15.70 15.78 17.78

1.59875 I * 59848 1.59751 1 .59634 1.59520 1 ,59370

Molar

yo of CSn. 91 .oo 90.88 90.51 90.0G 89.60

,

89.02

TABLEXIII. Distillates combined. No. 1

.......................

... ... ... Nos. 1 + 2 + 3 + 4 + 5 . . ........ Nos. 1 + 2 + 3 + 4 + 5 + 6 .......

ComCom% led bined CorncompoCorn- compobined sition. bined sition. weight. (Molar weight. Molar Distillates Grams. % (2%) CSn.) combined. Grams. 17.78 89.02 18.09 92.70 No. 6 . 36.37 90.94 Nos. 6 33.56 89.29 57.60 90.78 Nos. 6 49.35 89.54 70.58 89.83 73.39 90.63 Nos. 6 89.17 90.45 Nos. 6 + 5 + 4 + 3 + 2 .......... 88.86 90.04 106.95 90.21 Nos. 6 + 5 + 4 + 5 + 2 + 1 106.95 90.21

.f

.......

Original mixture (refractive index = 1.57895). ................ 83.04% CSs Corresponding vapor (by extrapolatio Residue (refractive index 1.56701). . . . . 77.69% CSa Corresponding vapor (by extrapolation), , . , . , , , , , , , , . , . , . . 88.63% CSz

-

.. .


1813

The results of Table XI11 are shown-graphically by the pair of curves 2. The relation between the composition of liquid and vapor is, on the basis of all the data given in this section, exhibited by the curves of Fig. 3. Here the lower curve indicates the boiling points of the various

E in Fig

Fig 3.

mixtures. Any horizontal line through the two curves will indicate the composition of a vapor (point of intersection with the upper curve) and of the liquid (point of intersection with the lower curve) in equilibrium with it. The case of carbon disulfide-carbon tetrachloride was experimentally a somewhat difficult one, owing to the two liquids interdiffusing rather slowly. Nevertheless, the results obtained by the present method are in satisfactory agreement with those yielded by the standard method mentioned above.' 1

Rosanoff and Easley, LOC.cit., p. 984.

1814

M. A. ROSANOFF,

C. W. BACON AND

R. €WHITE. I.

Section VI1.-Results for Chloroform-Toluene. TABLEXIV.-RTJN A. Weight of distillate. Grams.

No. of distillate. I

.........................

16.37 20.32 24.32 17.07 20.51

......................... 3 . . ....................... 4 ......................... 5 ......................... 2

Index of refraction. Molar % of CHC18. I

.44482

97 .oo 96.68 96.18 95.84 95.68

1 '44503

I .44532

1.44552 .44562

I

TABLEXV Combined comnn__-c_

Combined sition. weight. (Molar Grams. % CHCls.)

Dbtillates combined.

.................... Nos. 1+2 ................. Nos. 1+2+3 .............. Nos. 1+2+3+4 ...........

No. 1

NOS.

1+2+3+4+5

........

16.37 36.69 61.01 78.08 98.59

97.00 96.82 96.57 96.41 96.26

Distillates combined. No. 5 Nos. 5+4 Nos. 5+4+3 Nos. 5 + 4 + 3 + 2 Nos. 5+4+3+2+1

....................

................. ..............

........... ........

Original mixture (refractive index = 1.45153). . . . . . . . . . . . . . Corresponding vapor (by extrapolation). ................... Residue (refractive index = 1.45523). ..................... Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . .

Fig. 4.-Carbon

Combined compoCombined sition. weight. (Molar Grams. % CHCls.)

85.88% 97.25% 79.54% 95.40%

20.51 37.58 61.90 82.22 98.59

95.68 95.62 95.92 96.11 96.26

CHClr CHCla CHCls CHCla

disulphide-carbon tetrachloride.

The results of Table XV are shown graphically by the pair of curves A in Fig. 4.

I815


TABLEXVL-RWN B. Weight of distillate. Grams.

No. of distillate.

..................... 2 ......................... I....

3 ......................... 4 ......................... 5 ......................... 6 .........................

Index of refraction. Molar % of CHClr.

13.24 15.86 15.80 20.88 17.06

1 .44945

89.36 89.12 88.21 86.79 85.38 83.53

1 .44958

1.45013 I .45098 1.45183 1 ,45293

20.05

TABLE XVII. Distillates combined. No. l . . .

...... Nos. 1 + 2 + 3 . . . Nos. 1 + 2 + 3 + 4

Nos. 1+2$3+4 Nos. 1+2+3+4+5$6

Combined compo-. Combined sition. weight. (Molar Distillates Grams. % CHCb.) combined. 13.24 89.36 No. 6 29.10 89.23 Nos. 44.90 88.87 Nos. 65.78 88.21 Nos. 82.84 88.87 Nos. . . . . . 102.89 86.82 Nos.

Combined compoCombined sition. weight. (Molar 7 Grams. CHClr.7 20.05 83.53

Original mixture (refractive index = 1.46295) ... Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . . Residue (refractive index = 1.47015)...................... Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . .

65.33% 89.53% 51.30% 82.55 %

CHCli CHCk CHCb CHClt

The results of Table XVII are shown graphically by the pair of curves B in Pig. 4. TABLEXVIII.-RUN C. Weight of distillate. Grams.

No. of distillate.

......................... 2 ......................... 3 .......................... 4 ......................... 5.. ....................... 6 ......................... I

16.74 16.11 18.69 20.98 16.81 19.51

96 of CHClt. 93.20 92.68 92 .OI 91 19 90.36 89.12

Index of refraction. Molar

,44712 I ’ 44743 1.44783 1 .44833 1,44883 I ,44958 I

3

TABLEXIX. Combined compoCombined sition. Distillates weight. (Molar Distillates combined. Grams. % CHCL.) combined. 16.74 93.20 N o . 6 ....................... ...... 32.85 92.95 Nos. 6+5 .............. 51.54 92.23 Nos. 6+5+4 ........... Nos. 1+2+3+4 ........... 72.52 92.19 Nos. 6 + 5 + 4 + 3 89.33 91.85 Nos. 6 + 5 + 4 + 3 + 2 ..... Nos. 1+2+3+4+5 108.84 Nos. 1 + 2 + 3 + 4 + 5 + 6 91.36 Nos. 6 + 5 + 4 + 3 + 2 + 1 .......

...... ...... ........

Original mixture (refractive index = Corresponding vapor (by extrapolati Residue (refractive index = 1.46490) Corresponding vapor (by extrapolation).

........

...................

73.77% 93.38% 61.59% 88.20%

Combined Corn- cornpobined sition. weight Molar g Grams: CHCL.3 19.51 89.12 36.32 89.69 57.30 90.24 75.99 90.67 92.10 91.02 108.84 91.36

CHClr CHCL CHClr CHClr

1816


The results of Table XIX are shown graphically by the pair of curves C in Fig. 4. TABLE=.-RUN

D.


No. of distillate.

......................... ......................... 3 ......................... 4 ......................... 5 ......................... 6......................... I

2


Molar

% of CHCls.

1.45393 1.45473 1.45563 I.45693 I ,45818 I .46012

15.19 16.74 18.05 14.75 17.31 22.70

81.80 80.40 78.83 76.50 74.23 70 * 6.5

TABLEXXI. Combined compoCom- sition. Distil. bined (Molar latcs weight. % Distillates comGrams. CHCla.) combined. bined. Pu'o. 6 No. l . . . 15.19 81.80 Nos. 6+5 Nos. 1 + 2 31.93 81.06 Nos. 6+5+4 Nos. 1+2+3 49.98 80.25 Nos. 6 + 5 + 4 + 3 Nos. 1+2+3+4 64.73 79.39 Nos. 1+2+3+4+5 82.04 78.29 Nos. 6+5+4+3+2 Nos. 6+5+4+3+2+1. Nos. 1 + 2 + 3 + 4 + 5 + 6 104.74 76.61 Original mixture (refractive index = 1.46956). . Corresponding vapor (by extrapolation), ................... Residue (refractive index = 1.47820). Corresponding vapor (by extrapolation).

................... ................... ................ ............. ..........

Combined weight. Grams. 22.70 40.01 54.76 72.81 89.55 ...... 104.74 52.47% CHCla 82.60% CHClr 34.64% CHCls 68.59 % CHCL

....................... ...................

................ ............. .......... ~........... .....................

.......

...................

Combined composition. (Molar

%

CHCIs.) 70.65 73.19 73.34 74.69 75.75 76.61

The results of Table XXI are shown graphically by the pair of curves

D in Fig. 4. TABLEXXII.-RUN E. Weight of distillate. Grams.

No. of

distillate.

......................... ......................... 3. ........................ 4......................... 5 ......................... 6 ......................... I

2

14.47 15.49 14.02 19.31 13.44 14 * 55


I .4,5853 1 .45982

I ,46091

1.46255 1 .46450 I .46649

(Molar

% of CHCh.)

73.60 71.21 69.18 66.09 62.37 58.50

TABLEXXIII. Combined

Combined cornno-

Combined weight. (Molar yo Distillates Distillates Grams. CHCt.) combined. combined. 73.54 No. 6 ....................... 14.55 No. 1 14.47 Nos. 6+5 . . . . . . . . . . . . . . . . . . . 27.99 72.33 Nos. l + Z 29.96 Nos. 6+5+4 ................ 47.30 71.32 Nos. 1+2+3 .............. 43.98 69.71 Nos. 6 + 5 + 4 + 3 ............. 61.32 Nos. 1 + 2 + 3 + 4 63.29 Nos. 6+5+4+3+2 .......... 76.81 68.41 Nos. 1 + 2 + 3 + 4 + 5 76.73 Nos. 6 + 5 + 4 + 3 + 2 + 1 ....... 91.28 66.81 . Nos. 1 + 2 + 3 + 4 + 5 + 6 91.28 Original mixture (refractive index = 1.47442). ............. 42.61 % CHClr Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . . 74.80% CHCL Residue (refractive index = 1.48215). ..................... 26.02% CHCb Corresponding vapor (by extrapolation). 56.52% CHCL

.................... .................

........... ........

.....

...................

58.50 60.35 62.68 64.14 65.55 66.81


1817

T h e results of Table XXIII are shown graphically by the pair of curves E in Fig 4. TABLEXXIV.-RUN F. Weight of distillate. Grams. Index of refraction.

No. of distillate.

........................... z . . . ....................... 3 .......................... 4 .......................... 5 .......................... 6 .......................... I

1'46559 1.46589 I ,46813 1.46837 I ,46926 1 .47030

8.05

7.41 5.82 6.04 5.38 7.93

Molar % of CHCI:.

60.26 59.68 55.31 54.83 53.06 51.00

TABLEXXV. Distillates combined No. 1.............................. Nos. 1+2 ........................... Nos. 1+2+3 ........................ Nos. 1 + 2 + 3 + 4 ..................... Nos. 1+2+3+4+5 Nos. 1 + 2 + 3 + 4 + 5 + 6 . .

.

..................

.............

Combined weight. Grams. 8.05 15.46 21.28 27.32 32.70 40.63

Combined composition. (Molar YOCHCls.) 59.97 59.98 58.70 57.84 57.04 55.83

Original mixture (refractive index = 1.48074). ......... Corresponding vapor (by extrapolation).

.... ...................

29.13% CHCli 61.47% CHCl:

The residue in this case could not be analyzed. The results of Table XXV are shown graphically by the upper curve of pair F in Fig. 4. TABLEXXVI.-RUN G. Weight of distillate. Grams.

No. of distillate.

...................... ..........................

I.... 2

3 .......................... 4 .......................... 5 .......................... 6..........................

7.98 9.75 4.87 5.62 6.79 6.48

Index of refraction. I

.47261

1 * 47344 I .47526

1.47535 1.47624 1.47712

Molar

70 of CHCls. 46.34 44 * 65 40.86 40.68 38.81 36.95

TABLEXXVJI. Combined Distillates weight. combined. Grams. No. 1 ............................... 7.98 Nos. 1+2 ........................... 17.73 Nos. 1 + 2 + 3 ........................ 22.60 Nos. 1 + 2 + 3 + 4 28.22 Nos. 1+2+3+4+5 . . . . . . . . . . . . . . . . . . 35.01 Nos. 1 + 2 + 3 + 4 + 5 + 6 . . . . . . . . . . . . . . . 41.49

.....................

Combined composition. (Molar % CHCls.) 46.34 45.41 44.42 43.67 42.72 41.80

........... ...................

Original mixture (refractive index = 1.48483) 4.. Corresponding vapor (by extrapolation).

The residue in this case could not be analyzed.

19.99% CHCh 47.23% CHCla

1818


The results of Table XXVII are shown graphically by the upper curve of pair G in Fig. 4. The results of all our measurements in the case of chloroform-toluene are exhibited by the curves of Fig. 5 .

Fig. 5 .-Acetone-toluene.

Section V1II.-Results for Acetone-Toluene. TABLE XXVIII.-RUN A. No. of distillate.


I........ . . . . . . . . . . . . . . . . .

10.42

2..

12.57

.......................

3 ......................... 4 ......................... 5 .........................

6.........................


10.12

I. 36086 I .36104 I .36130 I .36148

11.48 11.29

1.36175 I ,36219

9.61

Molar ?& of acetone.

98.IO 98.01 97.89 97.82 97.72 97.52


I819

TABLEXXIX. Combined compoCombined sition. Distillates weight. (Molar % Distillates combined. Grams. acetone.) combined. No. l . . . 10.42 98.10 No. 6 Nos. 1+2 . . 22.99 98.05 Nos. 6+5 .... Nos. 1+2 .. 32.60 98.00 Nos. 6 + 5 + 4 Nos. 1 + 2 + 3 + 4 . . . . . . . . . . . 42.72 97.96 Nos. 6 + 5 + 4 + 3 Nos. 1 + 2 + 3 + 4 + 5 . . . . . . . . 54.20 97.91 Nos. 6 + 5 + 4 + 3 + 2 Nos. 1+2+3+4$5+6 . . . . . 65.49 97.84 Nos. 6 + 5 + 4 + 3 + 2 + 1

..

Combined compoCombined sition. weight. (Molar % ’ Grams. acetone.) 11.29 97.52 22.77 97.62 32.89 97.68 42.50 97.73 55.07 97.79 ....... 65.49 97.84 ~~~

.......

................ ..........

Original mixture (refractive index = 1.37023). ............. Corresponding vapor (by extrapolation). . Residue (refractive index = 1.37640). , . . Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . .

TABLEXXX.-Rm Weight of distillate. Grams.

No. of distillate.

.................... .........................

I..... 2

3 ......................... 4 .........................

5 . ........................

6 .........................

9.19 9.43 11.42 11.83 9.42 10.63

93.82% acetone. 98.10% acetone 90.67 yo acetone 97.40% acetone

B. Molar % of acetone.

Index of rdraction.

I * 36487

96.27 96.22 96.08 95.76 95 * 42 95.19

I * 36505 I 36532 I .36600

1.36677 I .36727

TABLEXXXI. Distqlates combined. No. 1 Nos. 14-2 . . . . . . . . . . . . . . . . . Nos. 1+2+3 Nos. 1 + 2 + 3 + 4 . . . . . . . . . . . Nos. 1+2+3+4+5.. Nos. 1 + 2 + 3 + 4 + 5 + 6 . . . . .

..................... ..............

Combined Combined compocompoCombined sition. Combined sition. weight (Molar Distillates weight. (Molar % Grams.’ acetone.? combined. Grams. acetone.) 9.19 96.27 No. 6 10.63 95.19 18.62 96.25, Nos. 6+5 30.04 96.18 Nos. 6+5+4. 41.87 96.08 Nos. 6 + 5 + 4 + 3 43.30 95.63 51.29 95.94 Nos. 6 + 5 + 4 + 3 + 2 .......... 52.73 95.74 61.92 95.82 Nos. 6 + 5 + 4 + 3 + 2 + 1 61.92 95.82

......................

....

....

.......

-

Original mixture (refractive index 1.38294) Corresponding vapor (by extrapolation) Residue (refractive index = 1.39361). . . Corresponding vapor (by extrapolation)

87.11% acetone

..

94.90% acetone

TABLEXXXII.--KUN C. Weight of distillate. Grams.

No. of distillate. I.....

....................

.................... 3 ......................... z.....

4 ......................... 5 ......................... 6.........................

8.62 12.68 11.58 13.45 9.53 10.22


Molar % of acetone.

I. 36968 I .36986

94.07 93.99 93.66 93 * I3 92.65 92.14

1.37050 I ,37160

1.37252 1.37354

AI. A. ROSANOFF, C. W. BACON AND R. H. WHITE.

1820

TABLEXXXIII. Distillates combined. No. 1 .................... Nos. 1+2 ... Nos. 1+2 ... Nos. 1 + 2 + 3 + 4

........... ...

Nos. 1 + 2 + 3 + 4 + 5 + 6

.....

Combined weight. Grsms. 8.62 21.30 32.88 46.33 55.86 66.08

Combined composition. (Molar o/o acetone.] 94.07 94.02 93.90 93.73 93.50 93.29

Distillates combined. No. 6 .................... Nos. 64-5 Nos. 6 + 5 Nos. 6+5 Nos. 6 + 5 + 4 + 3 + 2 Nos. 6+5+4$3+2+1

........

.....

Original mixture (refractive index = 1.39651). . . . . . . . . . . . . . Correspondfng vapor (by extrapolation). .................. ... Residue (refractive index = 1.41311).. . ... Corresponding vapor (by extrapolation)

Combined Corn- eompobined sition. weight. (Molar o/o 7 Grams. acetone.) acetone.7 10.22 92.14 92.37 19.75 33.20 92.69 44.78 92.94 57.46 93.17 66.08 93.29

79.0270 acetone 94.10% acetone 67.87% acetone 91.70% acetone

TABLEXXXIV.-RUN D. Weight of distillate. Grams.

No. of distillate.

......................... ......................... 3 ......................... 4 ......................... 5 ......................... 6 ......................... I

2


9.90

1,37534 1. 37558 I * 37651 1.37790 1 * 37950 I .38167

10.22

10.57 11.84 12.00 12.12

Molar % of acetone.

91.23 91.IO 90.61 89.88 89.01 87.82

TABLEXXXV. Combined Combined compocompoCombined sition. Combined sition. weight. (Molar weight. (Molar % Distillates 7 Distillates Grams. acetone.) combined. combined. Grams. acetone.7 9.90 91.23 No. 6 12.12 87.98 No. 1 . . . . . . . . . . . . . . . . . Nos. 14-2.. . . . . . . . . . . . 20.12 91.17 24.12 88.41 Nos. 6 Nos. 6 Nos. 1+2+3 30.69 90.98 90.68 Nos. 6 46.53 89.29 N o s . 1 + 2 + 3 + 4 ........... 42.53 NOS. 6 + 5 + 4 + 3 + 2 .......... 56.75 89.62 NOS. 1 + 2 + 3 + 4 + 5 ........ 54.53 90.31 Nos. 6 + 5 + 4 + 3 + 2 + 1 ....... 66.65 89.86 N o s . 1 + 2 + 3 + 4 + 5 + 6 . . . . . 66.65 89.86

..............

.............

Original mixture (refractive index = 1.41202). 68,64% acetone Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . 91.55% acetone Residue (refractive index = 1.43452). . . . . . . . . Corresponding vapor (by extrapolation). ...... 87.0070 acetone

TABLEXXXVI.-RTJN No. of distillate.

......................... ......................... 3 ......................... 4 ......................... 5 ......................... 6.........................


E.


I

10.44

I ,38191

2

12.12

I ,38280

11.52 11.56 11.46

1 .38470

11.80

38499 ,38965 1.39312 I

I

*

Molar % acetone.

87.68 87.20 86.10 85.95 83.22 81.11

PARTIAL VAPOR PRESSURES OF LIQUID MIXTURSS.

1821

TABLEXXXVII. Combined Combined compocompoCombined sition. Combined sition. weight. (Molar % weight. (Molar % Distillates Distillates Grams. acetone.) Grams. acetone.) combined. combined. No.' 6 . .: . . . . . . . . . . . . . . . . . . . 11.80 81.11 No. 1.................... 10.44 87.68 Nos. 6 + 5 . . . . . . . . . . . . . . . . . . . 23.26 82.10 Nos. 1 + 2 . . . . . . . . . . . . . . . . . 22.56 87.42 Nos. 6 + 5 + 4 . . . . . . . . . . . . 34.82 83.43 34.08 86.98 Nos. 1 + 2 + 3 86.72 Nos. 6 + 5 + 4 + 3 . . . . . . . . . . . . . 46.34 84.10 N o s . l + 2 + 3 + 4 . . . . . . . . . . . 45.64 84.75 86.03 NOS. 6 + 5 + 4 + 3 + 2 . . . . . . . . . . 58.46 NOS. 1 + 2 + 3 + 4 + 5 57.10 68.90 85.20 85.20 Nos. 6$5$4+3+2+1 Kos. I + 2 + 3 + 4 + 5 + 6 . . . . . 68.90 Original mixture (refractive index = 1.42767) Corresponding vapor (by extrapolation). ..... 88. 30Y0 acetone 35. 43y0 acetone Residue (refractive index = 1.45463). . . . . . . . Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . E O , 1570 acetone

........

TABLEXXXVIII.-RUN F. Weight of istillate ms.

No. of distillate.


I..................

1 .393Q2

39574 1 .39943 1 ,39943 I .4QQ4I I ,40247

1

4. . . . . . . . . . . . . . . . . . . 5 ..........................

3.44

f

Molar % of acetone.

81.16 79.49 77.18 77.18 76.54 75.19

TABLSXXXIX. Combined weight. Grams.

Comb!ned composition. (Molar % acetone.) 81.15 80.23 14.14 79.41 78.77 Nos. 1 + 2 + 3 + 4 + 5 ....+ . . . . . . . . . . . . . 23.38 78.44 Nos. 1+2+3+4+5+6 . . . . . . . . . . . . . . . 27.18 77.99 Original mixture (refractive index = 1.45143). . . . . . . . . . . . . . 38.29% acetone Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . 81.1 70acetone Distillates combined. No. 1 . . . . . . . . . . . . . Nos. 1 + 2 . . . . . . . . . . Nos. 1 + 2 + 3 . . ......................

The residue in this case could not be analyzed. TABLEXL.-RUN G . No. of distillate. I

..........................

5. . . . . . . . . . . . . . . . . . . 6 ..........................


3.04

Index of refraction. I .42O67

62.40

I .42267

60.92

I .42762

57.18 53.83 51.33 47.55

.43197 1,43518 I ,43994 I

5.79

Molar % of acetone.

TABLEXLI.

Combined Combined Distillates weight. composition. combine Grams. (Molar % acetone.) No. 1 3.04 62.39 Nos. 1 7.31 61.54 Nos. 1+2+3 ........................ 12.84 59.68 Nos. 1 + 2 + 3 + 4 . . . . . . . . . . . . . . . . . . . . . 17.58 58.14 Nos. 1$2 + 3 +4 + 5 . . . . . . . . . . . . . . 21.91 56.83 Nos. 1+2+3+4+5+6 27.70 54.95 Original mixture (refractive index = 1.47359). ............. 18.70% acetone Corresponding vapor (by extrapolation). 63.60% acetone

..................

M . A. ROSANOFF, C. W. BACON A N D R. H. WHITE.

1822

The residue in this case could not be analyzed. TABLEXLII.-RUN H. Weight of distillate. Grams.

No. of distillate.

.......................... .......................... 3 . ......................... I

2

4 .......................... 5 .......................... 6 .........................


5.36 3.86 5.99 5.90 4.94 6.64

1 .44386

I.44838

1.45233 1.45547 I

.4.5898

1 ' 46340

Molar % of acetone.

44.38 40.70 37.37 34.72 31.70 27.88

Fig. 6.-Chlorofcrrm-toluene. TABLEXLIII. Combined Combined weight. composition. Distillates Grams. (Molar % acetone.) combined. 44.38 No. 1 . .............................. 5.36 42-85 Nos. 1+2 ........................... 9.22 40.73 Nos. 1+2+3 ........................ 15.21 39.08 Nos. 1 + 2 + 3 + 4 . . ................... 21.11 37.71. Nos. 1 + 2 + 3 + 4 + 5 . . 26.05 35.78 Nos. 1 + 2 + 3 + 4 + 5 + 6 ............... 32.69 Original mixture (refractive index c 1.48221 ) . ............. 10.77y0 acetone 44.90% acetone Corresponding vapor (by extrapolation)

................

...................

1823


The residue in this case could not be analyzed. The results of all measurements in the case of acetone-toluene hibited by the curves of Fig. 6 .

for Ethyl Iodide-Ethyl

Section 1X.-Results

are ex-

Acetate.

TABLEXLIV.-RUN A. No. of distillate.


I ......................... 2

14.21

I ,38261

12.56

I .38246 I .38210 I .38167

...........

3 ......................... 4 .........................


12.50

s.... .....................

13.13 6...,... . . . . . . . . . . . . . . . . . . 11.66

Molar

I a38133 I .38106

7 ......................

1.38053

Combined compoCombined sition. Distillates weight. (Molar Distillates combined. Grams. % CzHsI.) combined. No. 1.................... 14.21 12.78 No. 7 Nos. 1 + 2 . . . . . . . . . . . . . . . . . 26.11 12.72 Nos. 7 Nos. 1 + 2 + 3 . . 38.67 12.57 Nos. 7+6+5 ... 51.17 12.40 Nos. 7+6+5+4 Nos. 1 + 2 + 3 + 4 + 5 64.30 12.23 Nos. 7 + 6 + 5 + 4 Nos. 1 + 2 + 3 + 4 + 5 + 6 . . . . . 75.96 12.08 Nos. 7 Nos. 1 + 2 + 3 + 4 + 5 + 6 + 7 . . 88.58 11.89 Nos. 7 Original mixture (refractive index = 1.37875). .............. Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . . Residue (refractive index = 1.37678). ...................... Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . .

... ........

% of C;HrI. 12.78 12.64 12.28 11.86 11.55 11.28 10.76-

Combined Com- compobined sition. weight. (Molar % Grams. CIHII.) . . . . 12.62 10.76

....

37.41 49.91 62.47

9.01% 12.95 % 7.05% 10.45 %

11.20 11.36 11.55

CzHd CzHsI C Y H ~ CzHaI

TABLEXLV1.-RUN B. Weight of distillate. Grams.

Ne. of distillate.

......................... z ......................... 3 ......................... 4 ......................... 5 ......................... I

6 .........................

10.93 16.39 15.63 14.64 15.64 19.62


yo of C ~ H I I . 21.26 21.15 20.47 19.94 19.35

Molar

I .39167 I .39158 I .39080

1.39023 I ,38956 I .38870

18.55

TABLEXLVII. Combined

Combined cornno___=_

Combined sition. weight. (Molar % Distil!ates Distil!aLes CzHs1.) combined. Grams. combiacd. 21.26 No. 6 ..................... 19.62 No. 1 . . . . 10.93 Nos. 6+5 Nos. I f 2 . . . . . 27.32 21.19 20.93 Nos. 6+5 49.90 Nos. l + 2 + 9 . . . . . . . . . . . . . . 42.95 20.68 Nos. 6+5 . . 65.53 Nos. 1 + 2 + 3 + 4 . . . . . . . . . . . 57.59 Nos. 6+5 Nos. 1 + 2 + 3 + 4 + 5 . . . . . . . . 73.23 20.39 Nos. l + 2 + 3 + 4 + 5 + 6 . . . . . 92.85 20.00 Nos. 6 + 5 + 4 + 3 + 2 + 1 92.85 Original mixture (refractive index = 1.38589). 15.9O%'CzHd Corresponding vapor (by extrapolation). . 21.75% CZHSI Residue (refractive index = 1.38242). ...................... 12.59% CzHd 18.00% CaHrI Corresponding vapor (by extrapolation).

..

..............

.

...................

.......

18.55 19.21 19.51 20.00

M. A. ROSANOFF,

~ S 2 4

C. UT.BACON AND R. H. WHITE.

TABLEXI,VIII.-RUN C . Weight of distillate. Grams.

No. of distillate.

I.........................

......................... 3......................... 4. . . . . . . . . . . . . . . . . . . . . . . . . 5 ......................... 6. . . . . . . . . . . . . . . . . . . . . . . . . 2

16.59 16.88 14.76 12.29 16.91 15.49


Molar % of CzHaI.

I .40IIg

29.74 29.31 28.63 28.21 27.68 26.96

I ,40070 1 I39992

,39943 '39884 I ,39802 I I

TABLEXLIX. Combined Combined compocompoCombined sition. Combined. sition. weight. (Molar (Molar Distillates Dis tilln tes weight. Grams. % CzHsI.) Grams. % CzHsI.) combined. combined. No. 1.. . . . . . . . . . . . . . . . . 16.59 29.74 NO. 6 . . . . . . . . . . . . . . . . . . . . . . 15.49 26.96 32.40 27.33 Nos. 1 4 . 2 . . . . . . . . . . . . 33.47 29.52 Nos. 6+5 . . . . 48.23 29.25 Nos. 6 + 5 + 4 44.69 27.57 60.52 29.04 Nos. 6 + 5 + 4 59.45 27.84 28.16 Nos. 1 + 2 + 3 + 4 + 5 77.43 28.74 Nos. 6 + 5 + 4 + 3 + 2 . . . . . . . . . . 76.33 Nos. 1+-2+3+4+5+6.. ... 92.92 28.44 Nos. 6+5+4+3+2+1 92.92 28.44 Original mixture (refractive index = 1.39390). . . . . . . . . . . . . . . 23.26% CzHaI Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . . 30.10% CaHsI 19.87% CzHsI Residue (refractive index = 1.39013) Corresponding vapor (by extrapolation). . . . . . . . . . . . . . . . . . . . 26.42% CzHaI

.......

The results in the case of ethyl iodide-ethyl acetate are exhibited by the curve of Fig. 7, in which the abscissae show the composition of the liquid and the ordinates that of the corresponding vapor. Owing to lack of material, only three runs were made in this case, yielding six points, within a range of about 257& of iodide in the liquid phase.

II I/

I/

Boiling Temperatures of the Mixtures.

Section X.-The

The boiling point curve of mixtures of carbon disulfide and carbon Fig. 7.-Ethyl iodide-ethyl acetate. Abscissae = molar per ethyl iodide tetrachloride, shown in pig. 3 , is based on measurements (under 760 in liquid. Ordinates = molar per cents ethyl iodide mm.) reported in an older communiin vapor. cation.' The curvesforchloroformtoluene (Fig. j) and acetone-toluene (Fig. 6) reproduce observations tabulated below. In the course of these observations, carried out with the aid of an Odd0 ebullioscope and standardized thermometers, the barometric pressure varied irregularly within one or two millimeters. No measures were taken to avoid this, since such variations of pressure could have no appreciable influence on the composition of the vapors. 0

1

/o

I

20

I

30

Rosanoff and Easky, LOG.cit., p. 982.

FREEZING POINT OF BENZENE IN THERMOMETRY.

TABLEL.-BOILING POINTSOF MIXTURESOF CHLOROFORM AND TOLUENE. BAR. PRESSURE, 743.7 * z mm. Molar % CHCls. Boiling point. Io8.g2n 0 103.58 7.86 15.96 98.72 25.46 93.38 88.30 34.64 83.94 43.33 78.17 54.44 64.66 73.65 69.67 74.70 65.35 86.54 Io0 61.33

1825

TABLE LI.-BOILING POINTS

OF

MIXTURES OF ACETONEAND TOLUENE. BAR. PRESSURE, 751.3 * 0.2 mm. Molar yo (CHa)zO. Boiling point. 0 109.43 88.28 14.99 34.63 74.93 51.42 68.77 65.98 64.37 61 .22 78.71 58.71 89.99 ID0 56.50

summary. A method and apparatus are described for determining the composition of vapors in equilibrium with liquid mixtures; the method is rapid and requires no special experience on the part of the manipulator. Also, results of measurements are given for the following four cases: Carbon disulfide-carbon tetrachloride, chloroform-toluene, acetone-toluene, and ethyl iodide-ethyl acetate. These data were needed here in connection with, a study of fractional distillation, and the measurements were therefore carried out isopiestically, under ordinary atmospheric pressure. It is a pleasure to gratefully acknowledge that the work described in this communication was rendered possible by a grant from the Rumford Fund of the American Academy of Arts and Sciences. WORCESIBR, MASS.

[CONTRIBUTION FROM THE W. GIBBS MEMORIAL LABORATORY OF HARVARD UNIVERSITY. ]

THE FREEZING POINT OF BENZENE AS A FIXED POINT IN THERMOMETRY. BY THEODORE W. RICHARDS AND JOHNW. SHIPLBY. Received July 3, 1914.

The transition temperatures of hydrated crystalline salts probably &ord the most convenient and exact means of fixing points on the thermometric scale between o o and rooo C. A number of these have been determined in this laboratory, chief among which are the transition temperature for sodium sulfate,l the dekahydrate of sodium chromate into hexahydrate and into tetrahydrate,2 the dihydrate of sodium bromide into the anhydrous the transition of manganese chloride from the tetra-

' Richards, Am. J . Sci. (1898); Richards and Wells, Proc. Am. Acad., 38,431 (1902). * Richards and 8

Kelley, Ibid., 47, 171 (1911); THISJOURNAL, 33, 847 (1911). Richards and Wells, Proc. Am. Acad., 41, 435' (1go6).

a rapid laboratory method of measuring the partial vapor pressures of

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