517 UC-NRLF SB 3M EXCHANGE The Dissociation of Electrolytes in Nonaqueous Solvents as Deter- mined by the Conductivity and Boiling-Point Methods DISSERTATION SUBMITTED TO THE BOARD OF UNIVERSITY STUDIES OF THE JOHNS HOPKINS UNIVERSITY IN CONFORMITY WITH THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY HENRY ROYER KREIDER June, 1910 EASTON, PA. ESCHENBACH PRINTING COMPANY 1911 The Dissociation of Electrolytes in Nonaqueous Solvents as Deter- mined by the Conductivity and Boiling-Point Methods DISSERTATION ^ U3MITTED TO THE BOARD OF UNIVERSITY STUDIES OF THE JOHNS HOPKINS UNIVERSITY IN CONFORMITY WITH THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY HENRY ROYER KREJDER EASTON, PA. ESCHENBACH PRINTING COMPANY 1911 1JLZ170 CONTENTS Acknowledgment 4 Introduction 5 PART I HISTORIC AL REVIEW: Nonaqueous Solvents 5 Mixed Solvents 6 PART II EXPERIMENTAL : Apparatus 17 Salts 19 Solvents 20 Solutions 20 EXPERIMENTAL DATA: Conductivity in Pure Solvents 21 Conductivity in Mixed Solvents 25 Boiling Point 31 THEORETICAL: Discussion of Results 32 Conductivity in Pure Solvents 32 Conductivity in Mixed Solvents 33 Ratios of Conductivity between Different Alcohols 43 Boiling Point Data 45 Summary 46 Biography 48 222270 ACKNOWLEDGMENT The author takes great pleasure in expressing a deep sense of appreciation and gratitude to President Remsen, Professor Morse and Professor Jones for instruction and advice which were at all times generously given both in the laboratory and in the lecture room. He also desires to thank Professor Renouf , Associate Pro- fessor Acree, Doctor Gilpin and Associate Professor Swartz. This investigation was undertaken at the suggestion of Pro- fessor Jones and pursued under his direction. The Dissociation of Electrolytes in Nonaqtieous Solvents as Determined by the Conductivity and Boiling-point Methods Four methods have been devised for measuring the disso- ciation of salts in solution: The conductivity and freezing- point methods, the solubility method of Nernst and Noyes, and the boiling-point method. Of these the conductivity and freezing-point methods are the best known, and are the most accurate. The solubility method of Nernst and Noyes is not widely applicable. Within recent years the boiling-point method has been so much improved by Jones and others that it gives fairly accurate results. There are certain objections to all of these methods. The conductivity and the freezing-point methods give good results in aqueous solutions, but in nonaqueous solutions which are less dissociated, their use has been attended with difficulty. In many of these solvents it has not been possible, previous to the present time, to determine /i^ accurately, and, conse- quently, the dissociation could not be calculated from the results obtained by the conductivity method. Many of the nonaqueous solvents freeze at a temperature so far below the ordinary that the application of the freezing-point method is often impossible. By means of the latest type of cell devised in this labora- tory, and which will be described later, we have been able to measure /t^ for a number of salts in methyl and ethyl alco- hols, and thus to calculate the dissociation of these salts in these solvents from the data obtained by the conductivity method. The dissociation of these same salts in the same solvents was determined by the boiling-point method with the object of finding if any relation exists between the results obtained by the two methods. HISTORICAL REVIEW. A large amount of work has been done with nonaqueous solvents, especially with the lower alcohols of the aliphatic series. These were soon found to have the property of dis- sociating salts to a considerable extent. Fitzpatrick 1 studied the conductivities of calcium nitrate, lithium nitrate, lithium chloride and calcium chloride in both methyl and ethyl alco- hols, and found values which were considerable, though less than those in water. Hartwig 2 measured the conductivity of a number of organic acids in both methyl and ethyl alco- hols. Paschow 3 worked with potassium iodide, cadmium iodide, calcium iodide, potassium acetate and sodium acetate in methyl alcohol. Vicentini 4 measured the conductivities of a number of salts of these alcohols. Cattaneo, 5 working with salts in ethyl alcohol, found that a number of those with which he worked have a negative temperature coefficient in this solvent. Vollmer 6 studied several salts over a large range of dilutions. Holland 7 investigated the effects of non- electrolytes on the conductivity of various salts in methyl alco- hol. Carrara's 8 work is very important. He carried out an extensive investigation on a large number of salts in methyl alcohol. Walden 9 did a large amount of work with pure organic solvents. The work of Dutoit and Aston 10 and of Frederich 11 is important. They formulated the hypothesis that the dissociating power of a solvent is a direct function of its degree of association in the pure state. Other workers in this field are Kablukoff, 12 Vollmer, 13 and Kahlenberg and Lincoln. 14 Mixed Solvents. Wakeman 15 carried out an investigation on organic acids in 1 Phil. Mag., 24, 378 (1893). 2 Wied. Ann., 33, 58 (1888); 43, 838 (1891). 3 Charcow, 1892. * Beibl.. Wied. Ann., 9, 131 (1885). 5 Ibid., 18, 219, 365 (1894). 8 Wied. Ann., 52, 328 (1894). 7 Ibid.. 50, 263 (1893). Gazz. Chim. Ital., [1] 26, 119 (1896). Z. physik. Chem., 5, 35 (1890). 10 Compt. rend., 125 240 (1897). " Bull. Soc. Chim., [3] 19, 321 (1897). Z. physik. Chem., 4, 432 (1889). Wied. Ann., 52, 328 (1894). " J. Phys. Chem., 3, 26 (1899). w Z. physik. Chem., 11, 49 (1893). mixtures of water and ethyl alcohol and found that the con- ductivity of these substances in these solutions decreased with increasing amounts of alcohol. Zelinski and Krapiwin 1 point out that the salts with which they worked, the iodides and bromides of sodium and ammonium in mixtures of 50 per cent. methyl alcohol and water, give a conductivity considerably less than the conductivity of these salts in either pure alcohol or water. Cohen 2 gives similar results with ethyl alcohol and water, and finds that potassium iodide in 80 per cent. alcohol shows a larger conductivity below V = 512 than in pure alcohol, but at a greater dilution the conductivity is less in the mixed solvents than it is in either of the pure sol- vents. Wakeman, 3 working with mixtures of ethyl alcohol and water, found that the equation, A 7 - r- = constant p(ioo-p) held for many substances in mixtures of the above-named solvents (A is the difference between the conductivity of the electrolyte in water and in the mixture, and p the percentage of alcohol by volume) . From his own and from Wakeman 's observations Cohen points out the following relation: constant. This relation holds independently of temperature and con- centration. He remarks that either the dissociation of the salt with which he worked is the same or that in these mixtures conductivity is not a direct measure of dissociation. Roth later found that the relation given by Wakeman holds, while that given by Cohen does not. Jones 4 and his coworkers have done a fairly large amount of work on conductivity and viscosity in mixed solvents. Since the following is essentially a continuation of that work a very brief review of the latter is necessary. 1 Z. physik. Chem., 21, 35 (1896). ? Ibid., 25, 31 (1898). *Jbid., 11,49 (1893). 4 Publication No. 80, Carnegie Institute. 8 Jones and Lindsay 1 found that the phenomenon discovered by Zelinski and Krapiwin is not confined to a few salts in mixtures of methyl alcohol and water only, but that it holds over a large range of salts and also in ethyl alcohol- water mix- tures. It holds less generally at 25 than at o, and in ethyl alcohol-water mixtures less than in methyl alcohol-water mix- tures. The conductivities were always less than the mean calculated from the conductivities in the pure solvents. As a partial explanation they advance the following tenta- tive suggestion: According to the theory of Dutoit and Aston only the polymerized molecules of the solvent dissociate the molecules of the solute. It is well known that water and the alcohols used are bighly associated substances. On coming into contact with each other, they break down the association of each other until equilibrium is reached; and, consequently, they have less dissociating power. In methyl alcohol-water mixtures where association of the constituents is greatest the dissociation is greatest. Other facts are in accordance with this suggestion. Since at the lower temperatures the associa- tion is greatest in the constituents, we would expect the great- est abnormality here. And such is the case. These conclusions were subsequently further confirmed by the cryoscopic work of Jones and Murray. 2 They worked with water and formic and acetic acids, and determined the molecular weights of each in the other by the freezing-point method. They found that the molecular weights of these substances are always less than the molecular weights of the pure substances as determined by the method of Ramsay and Shields. They thus conclude that the action of an as- sociated solvent upon another associated solvent is analogous to the action of an associated solvent upon an electrolyte. Jones and Carroll 3 extended the work of Jones and Lindsay. They worked with both binary and ternary electrolytes. As solvents they used methyl and ethyl alcohols and mixtures of these two. Acetic acid was also used. In mixed solvents 1 Am. Chem. J., 28, 329 (1902). Z. physik. Chem., 56, 129 (1906). 2 Ibid., 30, 193 (1903). Ibid., 32, 521 (1904). a minimum was found with the following salts: cadmium iodide, sodium iodide, and hydrochloric acid in mixtures of ethyl alcohol and water. That of cadmium iodide exists for dilutions up to 50 only, at o; beyond that there is no minimum. At 25 there is no minimum. Somewhat surprising results were found with hydrochloric acid in methyl alcohol and water mixtures; /*oo occurs at very low dilutions in mixtures containing up to 90 per cent, alcohol (between V 100 and V 200), while in 100 per cent. methyl alcohol it is not found even as high as V 2104. In the dilutions above these limiting values there is a decrease in conductivity. The relation pointed out by Wakeman, A = constant, P(ioo-p) does not hold ; neither does that of Cohen. They explain the cause of the minimum as follows:. There are two factors which determine conductivity, the amount of dissociation and ionic mobility. Decrease or increase of either of these produces a corresponding result in the conduc- tivity. They point out that there is a close connection between the fluidity and conductivity of a solution. These vary directly. When the solutions are brought together there is an increase in viscosity, or decrease in fluidity, which is its reciprocal. Consequently, the ions are much retarded in their movements and the conductivity diminished. As the temperature rises there is a shifting of the minima towards that mixture con- taining the greatest percentage of alcohol. In this shifting, however, the fluidity minima, they state, lag behind the con- ductivity minima. They propose the following hypothesis: "The conductivi- ties of comparable equivalent solutions of binary electrolytes in certain solvents (methyl and ethyl alcohol, other alcohols of the same series, acetone, etc.) are inversely proportional to the coefficients of viscosity of the solvent in question, and directly proportional to the association factor of the solvent 10 in question." These conclusions may be formulated as follows : = constant, or = constant. x a The work of Jones and Bassett 1 with silver nitrate in both methyl alcohol-water and ethyl alcohol-water mixtures deals with the same phenomena as were previously discussed. There are well marked minima in the curves at both o and 25 in methyl alcohol- water mixtures, but no such minima occur in ethyl alcohol- water mixtures. In all cases, however, the curves fall much below the straight line of averages. Jones and Bingham 2 measured the conductivities of lithium nitrate, potassium iodide, and calcium nitrate in water, methyl and ethyl alcohols and acetone, and binary mixtures of these solvents. They also made a large number of viscosity meas- urements of pure solvents, of mixed solvents, and of electro- lytes in solution. In acetone and water mixtures the same minima which previous workers had observed were also ob- served. While the conductivity minima are intimately related to the minima of fluidity, the conductivity curves of different salts show marked differences. In acetone and alco- hol mixtures the curves conform to the law of averages, that is, the conductivity curves are nearly straight lines. From this fact they conclude that the mixtures do not form more complex molecular aggregations. A peculiar fact, and one not previously known, was here discovered. Lithium and calcium nitrates in mixtures of acetone with methyl or ethyl alcohol present a very pronounced maximum of conduction. This must be due to one of two causes: There is either an increase in dissociation and, con- sequently, an increase in the number of ions present, or there must be a diminution in the size of the ionic spheres, causing them to move more rapidly. We eliminate the first cause since fluidities of mixtures of acetone and the alcohols obey the rule of averages. This would indicate that there is no in- crease in the molecular aggregation in these mixtures, and 1 Am. Chem. J., 32, 409 (1904). 2 Ibid., 34, 481 (1905). II according to Dutoit and Aston's hypothesis such a mixture would not dissociate to a greater extent than the constituent solvents. Since we can eliminate increased dissociation as the cause of the maximum, it must be due to the change in the dimensions of the ionic spheres. The previous work of Dutoit and Friederich and of Jones and Carroll is incomplete since it does not take into consideration the size of the ionic spheres. The tendency to show maxima in conductivity increases from potassium iodide through calcium nitrate to lithium ni- trate, which seem to show these effects most strongly. This may be connected with the ionic velocities, since potassium is a small ion and a comparatively rapidly moving one, and lithium forms, by combination with the solvent, a large ion and one that moves more slowly. Jones and Rouiller 1 worked with silver nitrate in the sol- vents used by Jones and Bingham. In a general way they found results similar to those previously obtained. There is a striking similarity in the curves at o and 25 in mixtures of ethyl alcohol and acetone. There is a pronounced max- imum at both o and 25 in the 25 per cent, acetone mixture in the more concentrated solutions, and shifting with increase in dilution through the 50 per cent, mixture to the 75 per cent, mixture. For pure acetone these curves decline rapidly. For mixtures of methyl and ethyl alcohols, the curves are nearly straight lines following the fluidity curves. Jones and McMaster 2 worked with lithium bromide and cobalt chloride in the same solvents that had been employed by Bingham. The fluidities of water, methyl alcohol, ethyl alcohol, and acetone, and binary mixtures of these solvents were measured. The conductivities of these mixtures with water show a well-marked minimum. This minimum shows an intimate relation to that of fluidity. Lithium bromide in mixtures of methyl and ethyl alcohols gives no minimum in conductivity. The curves are nearly straight lines, except at the higher concentrations where there is a slight sagging 1 Am. Chem. J., 36, 42 (1906). 2 Ibid., 36,325 (1906). 12 at both temperatures. The same salt shows a maximum in conductivity in acetone-methyl alcohol mixtures with 75 per cent, acetone. The maxima increase with rise in tem- perature. In acetone-ethyl alcohol mixtures the same charac- teristics are manifested. Cobalt chloride in methyl alcohol-water mixtures shows minima at both temperatures. At the higher temperature the minimum is most marked with 75 per cent, alcohol. In mixtures of ethyl alcohol and water, this salt shows a point of inflection at both temperatures and at all dilutions. These results are similar to those obtained by Jones and Bingham with calcium nitrate in acetone-water mixtures. In ethyl alcohol-methyl alcohol mixtures there is no distinct minimum but a sagging of the curve. The minimum of fluidity corresponds to that of conduc- tivity. There is in both methyl alcohol-water and ethyl alco- hol-water mixtures a tendency of the minimum to shift towards the mixture containing the greatest percentage of alcohol whenever there is a rise in temperature. The authors reach the conclusion suggested by former workers that a diminution in the fluidity of the solvent, which would bring about a corresponding decrease in ionic mobility, is an im- portant factor in causing the minimum in conductivity; and that the change in the size of the ionic spheres or the atmos- phere which surrounds the ions should also be taken into account. Several points in connection with the temperature coeffi- cients are important. In nearly every case the temperature coefficients are smaller in the more concentrated solutions. Jones had already explained the phenomena in the following manner: In practically all solutions there is combination between solvent and solute. As dilution increases the sol- vates become more complex. Change in temperature affects most greatly the complex solvates, therefore we should ex- pect the largest temperature coefficients at high dilutions. At certain concentrations in methyl alcohol and acetone a negative temperature coefficient manifests itself. Conduc- tivity varies directly as dissociation and fluidity. Since rise 13 in temperature diminishes dissociation, and increases fluidity, it would seem that there would be a point where these two influences would equalize each other, and the temperature coefficient become zero. This concentration is reached at V 200 in a 75 per cent, acetone and methyl alcohol mixture. Beyond this dilution there is a negative temperature coeffi- cient. Jones and Veazey 1 measured the conductivities and vis- cosities of solutions of copper chloride and potassium sulpho- cyanate in water, methyl alcohol, ethyl alcohol and acetone, and binary mixtures of thes,e solvents. The minimum which was previously observed with different electrolytes is here also observed in some cases. This minimum is more pro- nounced at the higher dilutions. Where no minimum oc- curs there is a decided fall below the average value for the pure solvents. There is an interesting difference in the values for molecular conductivity in the pure solvent with increasing dilutions. In pure water, copper chloride, a ternary electrolyte, shows a much greater conductivity than potassium sulpho- cyanate, a binary electrolyte. In pure methyl alcohol the opposite condition exists. The conductivity of potassium sulphocyanate is the greater. This fact appears in previous work. Ethyl alcohol shows the same phenomenon. The temperature coefficients of conductivity increase with increase in dilution. There is one exception cobalt chloride in methyl alcohol. A marked negative temperature coeffi- cient of viscosity is shown by potassium sulphocyanate in aqueous solutions. In a recent communication Jones and Veazey 2 report the results of a study of solutions of tetraethylammonium iodide in mixtures of water, the alcohols and nitrobenzene. In mix- tures of the alcohols and water there is a well-defined minimum in conductivity. In mixtures of the alcohols with each other there is no minimum, although the curves fall below the aver- ages. In methyl alcohol and nitrobenzene the same phe- nomena occur, but in ethyl alcohol and nitrobenzene there is 1 Am. Chem. J., 37, 405 (1907). Z. physik. Chem., 61, 41 (1908). 2 Am. Chem. J., 41, 433 (1909). 14 a maximum. The conductivity curves correspond very well with the fluidity curves. Jones and Mahin 1 took up the study of cadmium' iodide and lithium nitrate in binary mixtures of water, methyl and ethyl alcohols and acetone, and lithium nitrate hi ternary mixtures of these solvents. Viscosity measurements of these solutions were also made. These measurements were carried to as high dilutions as possible in some cases as high as 200,000 liters. At these high dilutions it was impossible to prevent considerable error due to the large correction for the specific conductivities of the solvents, and the large cell constants. With lithium nitrate the product of viscosity and molecular conductivity is nearly a constant for mixtures of acetone with methyl alcohol and ethyl alcohol. This value is independent of the temperature. The value is nearly o . 70, which is Walden's value for tetraethylammonium iodide. With acetone-water mixtures the product varies between i.oo, the value for water, and 0.63, the value for acetone. Interesting results were obtained by determining the molec- ular weights of lithium nitrate in acetone by the boiling-point method. The object was to test the assumption that the low conductivity of this salt in ordinary solutions is due to the association of the salt. In the most dilute solution 0.09 normal which could be determined accurately, the boiling- point method showed a molecular weight of 83.1, while the normal molecular weight is 69.07. We can, therefore, con- clude that there is association, and this would account for the low conductivity in solutions at great dilutions. Jones had already shown that cadmium iodide in acetone is associated. This salt was next investigated and found to behave like lithium nitrate in its molecular conductivity. There is an irregularity in the product of conductivity and viscosity in acetone and methyl alcohol mixtures, while in the pure solvents these products are nearly the same. In acetone-ethyl alcohol mixtures there is a fair degree of con- stancy in these products. Jones has shown that there is considerable polymerization of cadmium iodide in acetone. 1 Z. physik. Chem., 62, 41 (1908). 15 Conductivity and viscosity in ternary mixtures of the above solvents were next taken up, and a considerable amount of work was done. The object was to determine whether any essentially new pricinples could be discovered by increasing the number of components in the solvent mixture. The re- sults are about what we would expect from a knowledge of the behavior of solutions in binary solvent mixtures. Turner, 1 working in Jones's laboratory, made various con- ductivity measurements of potassium iodide, lithium chloride and lithium bromide in pure ethyl alcohol, at high dilutions. Many precautions were pointed out which were very helpful in the present work. The purification of solvents, precau- tions necessary to prevent contact with foreign substances, and other sources of error were investigated and discussed in detail. After repeated experiments it was found that small traces (0.2 to 0.3 per cent.) of water do not appreciably affect the conductivity. The conductivity of potassium iodide in ethyl alcohol was measured up to a dilution of 450,000 liters. A maximum of molecular conductivity of 48.5 was reached at about 20,000 liters. From this the ionization was calculated. Measure- ments of conductivity were made at as high as 78. The tem- perature coefficients increase with increasing temperatures and with increasing dilution. Ionization decreases consid- erably with rise in temperature. A o . i normal solution is dissociated 49 per cent, at o, 46 per cent, at 25 and about 35 per cent, at the boiling point of ethyl alcohol. Determinations of ionization were also made by the boiling- point method, but these are in all cases considerably lower than those obtained by the conductivity method. The work of Jones and Schmidt' 8 introduces a new solvent, glycerol. They measured the conductivity and viscosity of lithium bromide, cobalt chloride, and potassium iodide in glycerol, methyl and ethyl alcohols, and binary mixtures of these and water. Glycerol was employed as a solvent be- cause of its high viscosity. Its dielectric constant is about 1 Am. Chem. J., 40, 558 (1908). 2 Ibid., 42, 37 (1909). i6 one-fifth that of water and it ought to have a fairly high dis- sociating power. It has remarkable solvent properties. But little work had previously been done with glycerol as a sol- vent. For measuring viscosity a viscometer with especially large bore had to be constructed. Measurements of conductivity were made at 25, 35 and 45. Lithium bromide in mixtures of glycerol with water, methyl alcohol, and ethyl alcohol shows no minimum, but there is a wide departure from the law of averages, and a marked sagging in the curves. We would hardly expect a minimum since there is probably no mixture of glycerol with these other solvents which is more viscous than glycerol itself. With cobalt chloride the conductivities in pure glycerol increase regularly. The conductivity values are considerably higher than the corresponding values for lithium bromide. Since cobalt chloride is a ternary electrolyte and lithium bromide a binary one, these results are just what we should expect. In pure ethyl alcohol, however, the case is different. The values for the conductivity of cobalt chloride are ab- normally low. Lithium bromide, for instance, in a o . i N solution has a molecular conductivity of 15.8 at .25. We should expect that cobalt chloride, since it is a ternary elec- trolyte, would have a conductivity probably 50 per cent, greater, but the value for the molecular conductivity of cobalt chloride in ethyl alcohol at the above concentration is only 4.71. Many of the halides of the heavy metals tend to form complexes when dissolved in organic solvents. It was sup- posed that the low conductivity of cobalt chloride in ethyl alcohol, at least in the more concentrated solutions, was due to polymerization of the molecules. Molecular weight deter- minations of cobalt chloride in ethyl alcohol were made by the boiling-point method. The mean of three determina- tions is 140 at about one-twelfth normal concentration, while the molecular weight for the compound CoCl 2 is 129.9. This would seem to indicate that there is association and, conse- quently, a lower conductivity than would be expected. Potassium iodide in glycerol behaves like the other salts. There is a slight increase in conductivity with dilution. In each case the conductivities for mixed solvents are less than the average for pure solvents. A new feature is the magnitude of the temperature coeffi- cients of conductivity. Some are almost as high as nine per cent. Cobalt chloride in ethyl alcohol manifests a negative temperature coefficient. A negative viscosity manifests itself in the case of potassium iodide in water, and in 25 per cent, and 50 per cent, glycerol and water at both 25 and 35. An elaborate investigation has been carried out in this laboratory during the past year by Guy on glycerol as a sol- vent. The results of this work will soon be published. EXPERIMENTAL. This investigation was undertaken for the purpose of ob- taining facts by means of which the following questions might be answered : 1. At what dilutions do the maxima in conductivity occur for various salts in methyl and ethyl alcohols? 2. Is there any relation between these maxima in conduc- tivity for different salts in different solvents? 3. What is the magnitude of the dissociation of these salts in these solvents as calculated by means of the maxima in conductivity? 4. What relation does this dissociation bear to that found by means of the boiling-point method? Apparatus. The Kohlrausch method was used. The wire was calibra- ted and was found to be of uniform thickness throughout. The cells were of the latest type used in this laboratory. They were devised for measuring the conductivity of very dilute solutions where there is great resistance. They con- sist of two concentric platinum cylinders so placed one within the other that the electrodes are only about i mm. apart. They are held together by means of small drops of fusion glass placed between them. These electrodes have a surface of about 48.75 square cm. One of these cells had a constant as low as 2.82. The vertical position of the electrodes per- i8 mitted the ready escape of all air bubbles, neither were they difficult to wash and dry if the proper precautions were ob- served. These cells gave excellent results, and a sharp min- imum was obtained upon the bridge without difficulty. The constants were determined by means of o.oi N and o.ooi N solutions of potassium chloride. These constants were fre- quently redetermined but were found to change but little throughout the work. All the appparatus was carefully calibrated. The necessary precautions concerning temperature were observed. The temperature in the 25 bath was regulated with a sensitive ez^ ^ J f^-- Fig. I. Type of cell employed in this work. thermometer calibrated against a German Reichanstalt ther- mometer. The o bath was from time to time tested to see that there was no change in temperature. At no time were measurements made when the temperature varied more than o.04 from that required. Careful tests were made to find the time required for the temperature of the solutions within the cells, both at o and 25, to reach an equilibrium. This equilibrium was indicated by a constant conductivity. In all cases nearly an hour was necessary. Three readings were always taken and the mean was employed. For o measurements a battery jar filled with ice and water was placed within a bucket and surrounded with ice and water. The cells were placed in the battery jar and covered 19 with glass. Ample time was allowed for the temperature to reach an equilibrium. Frequently the first reading was repeated after an interval of fifteen minutes or more, insuring equilibrium. Extreme precautions were necessary in washing the ap- paratus. No fumes were permitted in the room. Immediately before using, the cells and flasks were thoroughly washed with distilled water, then rinsed several times with conductivity water and finally washed repeatedly with alcohol. This alco- hol was always kept pure and used only a few times before it was dried and redistilled. Ether was not employed in drying since there is danger of fats being contained in it. The ap- paratus was then carefully dried. Before a solution was made up in a flask the latter was rinsed with a portion of the solvent, and the cell was rinsed with a portion of the solution. In many cases of very dilute solutions the flask in which the solution was to be made up was first cleaned, dried and rinsed with alcohol, the conductivity of this alcohol determined, and this same alcohol was employed to dilute the solution and its conductivity was used for the correction for the specific conductivity of the solvent. As a rule, there was lit- tle change in this conductivity when the above precautions were observed, and yet, because of the large volume, this change was at times quite appreciable. Salts. The salts used were potassium iodide, ammonium bromide, potassium sulphocyanate, lithium nitrate, sodium iodide, copper chloride, calcium nitrate and cobalt chloride. In all cases the necessary precautions were observed in purifying the salts, Kahlbaum's best products being employed. All were recrystallized a number ,of times, finally from con- ductivity water and some from absolute alcohol. All were dried at a temperature of 125- 150. Those which are very deliquescent were heated for a long time, some for several days, in ah air bath. Those chlorides which readily form oxychlorides when heated in the air were recrystallized several times, then dried in a vacuum desiccator over sulphuric acid 20 for several days, and finally heated for a long time in a cur- rent of dry hydrochloric acid gas. They were then placed in a desiccator over sulphuric acid and potassium hydroxide for several days. All other salts but the latter class were dried to constant weight before making up each solution. Solvents. The solvents used were methyl and ethyl alcohols and mix- tures of these with water. Considerable difficulty was ex- perienced in purifying methyl alcohol so as to obtain it with as low a specific conductivity as possible. This low conduc- tivity was important since there was danger of introducing considerable error due to the large correction for the specific conductivity of the solvent at these high dilutions. It was evident from the results that some foreign substance was con- tained in the methyl alcohol which it was difficult to remove. It was supposed that this unusually high conductivity was due probably to pyridine bases, and that these might be re- moved by treatment with sulphuric acid. The cold alcohol was treated with a small quantity of dilute sulphuric acid. It was then distilled, the first runnings being always discarded, and the receiver removed while a considerable quantity was still in the flask. The alcohol was then boiled with lime for a day and distilled. In some cases it was repeatedly treated with lime and repeatedly distilled. One quantity thus treated gave a conductivity as low as 7. i X io~ 7 . On standing, how- ever, the conductivity changed somewhat, so that not all work was done with alcohol having quite such low conduc- tivity. The ethyl alcohol was distilled from lime several times, then repeatedly distilled until it had a conductivity of about 2.6 X io~ 7 . The water was purified by the method of Jones and Mackay. Solutions. All solutions were made by direct weighing. In those cases where the solutions were to be very dilute and but a small quantity of the salt was needed, a o . i N solution was made as a mother solution. This was then diluted to a second mother 21 solution. From this the final dilutions were made directly. Only in a few cases was a final dilution made from any other but the first or the second mother solution. All solutions were made up at 20. Enough time was al- ways allowed for the temperature to come to equilibrium. The solutions when once placed in the cells were not removed from them until after measurements were made for both temperatures. They were never left in the cells longer than necessary because of possible decomposition : Table I. Conductivity of Potassium Iodide in Methyl Alcohol ato and 2*>. V. 0. 25. Temperature coefficients. 1024 69.05 96.18 0.01572 2048 70.62 99.22 O.OI62O 4096 71.48 101. 14 0.01660 8192 72.13 102.4 0.01679 16384 74-5 104.8 0.01627 32768 76.6 107.2 0.01598 Table II. Conductivity of Potassium Iodide in Ethyl Alcohol ato and 25. Temperature V. 0. 25. coefficients. 1024 23.4 36.4 0.02222 2048 28.6 44-9 0.02280 4096 29.4 47 - 2 0.02422 8192 32.7 47.5 0.01810 16584 32.5 47.4 0.01834 33168 32.0 47.2 0.01900 Table III. Conductivity of Ammonium Bromide in Methyl Alcohol at o and 25. Temperature V. 0. 25. coefficients. 1024 66.1 93.1 0.01634 2048 69.9 94.1 0.01377 4096 70.6 96.7" 0.01482 8129 71.8 96.8 0.01393 16584 69.2 94.9 0.01485 22 Table IV. Conductivity of Ammonium Bromide in Ethyl Alcohol at o and 25. V. 0. 25. Temperature coefficients. 1024 32.1 37-0 O.O2O47 4096 25.2 39-6 0.02285 16384 27-5 39-i 0.01687 65536 29.8 39-5 O.OI3O2 Table V. Conductivity of Potassium Sulphocyanate in Methyl Alcohol at o and 25. Temperature V. 0. 25. coefficients. 1600 69.1 98.3 0.01690 3200 71.1 101 .0 0.01682 12800 73-o 103.7 0.01682 25600 83.5 106.3 0.01092 Table VI. Conductivity of Potassium Sulphocyanate in Ethyl Alcohol at o and 2$ ( V. 0. 25. Temperature coefficients. 1600 28.2 43-8 0.02218 3200 28.6 45-7 0.02391 6400 29.2 46.67 0.02393 12800 29.23 45-4 0.02213 25600 28.57 43-64 0.02 I 10 Table VII. Conductivity of Lithium Nitrate in Methyl Alco- hol at o and 25. Temperature V. 0. 25. coefficients. 1600 58.83 83.24 0.01659 3200 59-89 85.98 0.01743 6400 61 .46 89.29 O.OlSlI 12800 59-69 91-35 0.02 12 I 25600 60.36 93.61 O.O22O3 Table VIII. Conductivity of Lithium Nitrate in Ethyl Alcohol at o and 25. Temperature V. 0. 25. coefficients. 1600 23.82 36.67 0.02157 3200 24.13 38.44 0.02372 6400 25-63 40.87 0.02378 12800 25.87 40.02 0.02187 25600 43-30 . OOOOO Table IX. Conductivity of Sodium Iodide in Methyl at o and 25' V. 0. 25. Temperature coefficients. 512 60.32 87.67 O.Ol8l4 1024 64.15 90.91 0.01669 2048 63-65 91-93 0.01777 4096 63-34 91 .06 0.02382 8192 65.90 93-40 0.01669 16384 63.1 91.8 O.Ol8l9 Table X. Conductivity of Sodium Iodide in Ethyl Alcohol at and 25. Temperature V. 0. 25. coefficients. 512 24.41 38.06 0.02237 1024 25.12 39-66 0.02315 2048 25.89 40.92 O.O2322 4096 26.89 41.84 0.02224 8192 26.06 42.86 0.02579 16384 26.79 42.02 O.O2274 32768 28.8-3 43.22 O.OI996 Table XL Conductivity of Calcium Nitrate in Methyl Alco- hoi at o and 25. Temperature V. 0. 25. coefficients. 1600 83.53 IO6.O4 O.OIO78 3200 93-50 120.58 O.OII56 6400 105.46 138.46 O.OI252 12800 112.52 I5L73 0.01394 25600 119.44 164.6 O.OI509 51200 124-58 175.0 O.OI620 Table XII. Conductivity of Calcium Nitrate in Ethyl Alcohol at o and 25. Temperature v. 0. 25. coefficients. 1600 17.19 24.48 0.01696 3200 19. ii 29.52 O.O2I79 6400 21-45 34.16 0.02370 12800 24.22 39-23 0.02537 25600 27.61 45.67 O.O26l6 51200 31.92 51.62 0.02469 24 Table XIII. Conductivity of Cobalt Chloride in Methyl Alcohol ato and 25. Temperature V. o*. 25. coefficients. 1600 101 .94 138.58 O.OI438 3200 110.98 152.34 0.01878 6400 115.76 162.38 o. 01612 12800 116.22 165-74 0.01704 25600 ii5-34 166.08 0.01760 51200 112.58 I57-96 9.01614 Table XIV Conductivity of Cobalt Chloride 1 in Ethyl Alcohol ato and 25. Temperature V. 0. 25. coefficients. 1600 19.99 25.61 O.OII25 3200 22.75 30.13 0.01298 6400 25.68 34-15 O.OI3I9 12800 29.25 39-Qi 0.01335 25600 3I-36 43.62 0.01564 51200 31.62 46.31 0.01858 102400 28.42 (52.26) . 00000 Table XV. ( Conductivity of Copper Chloride in Methyl Alco- hol at o and 25. Temperature V. 0. 25. coefficients. 1600 64-13 78.58 0.09013 3200 75-43 89-31 0.07361 6400 85.22 101.28 0.07538 12800 91-3 112.3 0.09201 25600 90.5 116.4 O.OII45 51200 79.1 112. I 0.01669 Table XV I. Conductivity of Copper Chloride in Ethyl Alco- hoi ato and 25. Temperature V. 0. 25. coefficients. 1600 16.08 20.96 O.OI2I4 3200 18.94 25-74 0.01436 6400 21 .06 30.70 O.OI83I 12800 22.52 34.16 O.O2067 25600 22.94 37-79 0.02589 25 Table XVII. Conductivity of Potassium Iodide in a Mixture of 25 Per Cent. Methyl Alcohol and Water. Temperature V. 0. 25. coefficients. 1024 45-03 90.44 0.04023 2048 44.26 91.60 0.04278 4096 45.60 92.80 0.04140 8192 45-56 92.40 0.04II2 16384 48.60 96.0 o . 04000 32768 51-99 100-7 0.04517 Table XVIII. Conductivity of Potassium Iodide in a Mixture of 50 Per Cent. Ethyl Alcohol and Water. V. 0. 25. Temperature coefficients. 1024 35-77 72.24 0.04078 2048 36.07 73-37 0.04137 4096 37-49 74.64 0.03968 8192 38.04 76.20 0.04013 16384 40.18 79-9 0.03945 36768 46.86 93-i 0.03948 Table XIX. Conductivity of Potassium Iodide in a Mixture of 75 Per Cent. Methyl Alcohol and Water. V. 0. 25. Temperature coefficients. 1024 41-63 71-37 0.04952 2048 41 .20 72.00 o . 05064 4096 41.82 73-19 0.05247 8192 44.98 75-41 0-05475 16384 46.83 75-3 0.05339 32768 49-95 71.8 O.OI9IO Table XX. Conductivity of Potassium Iodide in a Mixture of 25 Per Cent. Ethyl Alcohol and Water. Temperature V. 0. 25. coefficients. 1024 32.38 74-80 0.05241 2048 32.75 76.23 0.053II 4096 32.73 76.60 0.05361 8192 33-88 77.20 0.05II5 16584 35-30 80.3 0.05138 33168 39-88 86.8 o . 04702 26 Table XXL -Conductivity of Potassium Iodide in a Mixture of 50 Per Cent. Ethyl Alcohol and Water. Temperature V. 0. 25. coefficients. 1024 20.04 52.12 0.06401 2048 20.92 52.83 O.O6O73 4096 21.28 53-20 o . 06000 8192 21.34 54-09 0.06120 16384 20.94 55-23 0.06550 32768 23.10 59-i6 0.06244 Table XXII. Conductivity of Potassium Iodide in a Mixture f 75 P er Cent. Ethyl Alcohol and Water. Temperature V. 0. 25. coefficients. 1024 20.58 44.14 0.04579 2048 21-39 45-04 0.04423 4096 21.50 45-91 0.04541 8192 21.34 45-96 0.04615 16384 21.85 47-85 0.04760 32768 23-68 51.04 0.04491 65536 25.11 53-30 0.04491 Table XXIII. Conductivity of Cobalt Chloride in a Mixture of 25 Per Cent. Methyl Alcohol and Water. Temperature V. 0. 25. coefficients. i6oo 66.85 I44.I 0.04620 3200 68.20 148.5 0.04831 6400 69-39 I5I.8 0.04749 12800 70.50 152.3 0.04641 25600 72.08 159-0 0.04823 51200 80.30 181.6 o . 05046 Table XXIV. Conductivity of Cobalt Chloride in a Mixture of 50 Per Cent. Methyl Alcohol and Water. V. 0. 25. Temperature coefficients. 1600 53-94 II3-5 0.04417 3200 55-84 II5-7 0.04287 6400 56.59 IIQ.4 o . 04440 12800 57.86 122.3 0.04456 25600 58.70 124. I 0.04457 51200 65.2 138.6 0.04503 27 Table XXV. Conductivity of Cobalt Chloride in a Mixture of 75 Per Cent. Methyl Alcohol and Water. V. 0. Temperature 25. coefficients. 1600 56.23 IOI-5 O.O322O 3200 63.32 II5.4 0.03290 6400 64.22 118.1 0.03356 12800 66.48 120-7 O.O3262 25600 66.2 122.3 0.93390 51200 69.0 124.9 0.63241 Table XXVI. Conductivity of Cobalt Chloride in a Mixture of 25 Per Cent. Ethyl Alcohol and Water. Temperature V. 0. 25 . coefficients. 1600 47 . 92 II9.7 0.05992 3200 49. 08 123.6 0.06072 6400 50 . 80 127.4 O.O6032 12800 50.73 129.7 O.O6227 25600 51-83 135.0 0.06419 51200 57-74 154.4 0.06697 162400 60.20 170.5 0.07327 Table XXVII Conductivity of Cobalt Chloride in a Mixture of 50 Per Cent. Ethyl Alcohol and Water. Temperature V. 0. 25 . coefficients. 1600 31.16 81.56 0.06469 3200 32.27 84.67 0.06495 6400 32 . 70 86.56 0.06588 12800 33-70 88.28 0.06479 25600 33.25 87.42 0.06517 51200 34 -^ 90.8 0.07743 102400 34-40 89.7 O.07609 Table XXV 1 1 1. Conductivity of Cobalt Chloride in a Mixture of 75 Per Cent. Ethyl Alcohol and Water. Temperature V. 0. 25. coefficients. 1600 31.0 67.1 0.04658 3200 32.4 70.5 0.04704 6400 33 . i 73.4 0.04870 12800 33.7 74.6 0.04855 25600 34.4 74.8 0.04698 51200 34.0 72.4 0.04518 28 Table XXIX. Conductivity of Potassium Iodide in Mixtures of Methyl Alcohol and Water at o. V. per cent. 25 per cent. 50 per cent. 75 per cent. 100 per cen 1024 87.9 45.0* 35-8 41.6* 69. I 2048 88.5 44-3 36.1 41.2 70.6* 4096 88.9 45-6 37-5 41.8 71-5 8192 89.2* 46.6 38.0* 45-o 72.1 16384 89.2 46.6 40.2 46.8 74-5 32768 89.2 52.0 46.9 49-9 76.6 Table XXX. Conductivity of Potassium Iodide in Mixtures of Methyl Alcohol and Water at 25. V. per cent. 25 per cent. 50 per cent. 75 per cent. 100 per o 1024 135-6 90.4 72.2 71.4 96.2 2048 136.2 91.6 73.4 72.0 99-2 4096 136.7 92.8* 74.7 73-2 IOI.I 8192 136.9* 92.4 76.2 75-4* IO2.4 16584 136.9 95-3 79-9 75-3 104.8 33168 136.9 100.7 93-i 71.8 107.2 Table XXXI. Conductivity of Potassium Iodide in Mixtures of Ethyl Alcohol and Water at o. nt. 100 per cent. 23-4 28.6 29.4 32.7* 32.5 32.0 Table XXXII. Conductivity of Potassium Iodide in Mixtures of Ethyl Alcohol and Water at 25. V. per cent. 25 per cent. 50 per cent. 75 per cent. 100 per cent. F. per cent. 25 per cent. 50 per cent. 75 per ce 1024 87- 9 32.4 20 .O 20. 6 2048 88. 5 32.8* 20 9 21 . 4 4096 88. 9 32.7 21 3* 21 . 5 8192 89. 2 * 33-9 21 3 21 . 3 16584 89. 2 35-3 20 9 21 . 8 33168 89. 2 39-9 23 ,i 23- 7 65536 25- i IO24 135.6 74.1 52-1 44.1 36.4 2048 136.2 76.2 52-8 45-0 44.9 4096 136.7* 76.6 53-2 45-9 47.2 8192 136.9 77.2 54. i 46.0* 47-5 16584 136.9 80.3 55-2 47-9 47-4* 33 l6 8 136.9 86.8 59-2 51-0 47-2 29 Table XXXIII Conductivity of Cobalt Chloride in Mixtures of Methyl Alcohol and Water at o. V. 25 per cent. 50 per cent. 75 per cent. 100 per cen 1600 66.9 53-9 5 6.2 101 .9 3200 68.2 55-8 63.3 III .0 6400 69.4 56.6 64.2 II5.8 12800 75-5* 57-9 66.5* 116.2* 25600 72.1 58.7 66.2 115.3 51200 80.3 65-2 69.0 112 .6 Table XXXIV. Conductivity of Cobalt Chloride in Mixtures v. of Methyl Alcohol and Water at 25. 25 per cent. 50 per cent. 75 per cent. 100 per cent. 1600 144.1 II3-5 101.5 138.58 3200 148.5 II5-7 II5-4 152.34 6400 151.8 119.4 118.1 162.38 12800 152.3 122.3 120.7 165.74 25600 159-0 124. i 122.3 166.1 51200 181.6 136.6 124.9 158.0 Table XXXV. Conductivity of Cobalt Chloride in Mixtures of Ethyl Alcohol and Water at o. v. 25 per cent. 50 per cent. 75 per cent. 100 per cent. 1600 47.92 31.16 31.0 19.99 3200 49.08 32.27 32.4 22.75 6400 50.80* 32.70 33-i 25-68 12800 50.73 33 70* 33.7 29.25 25600 51.83 33.25 34-4* 31-36 51200 57.74 34-i8 34-o 31.62* 162400 60.20 34-40 28.42 Table XXXVI. Conductivity of Cobalt Chloride in Mixtures of Ethyl Alcohol and Water at 25. V. 25 per cent. 50 per cent. 75 per cent. 100 per cent. 1600 II9.7 81.56 6 7 .I 25.61 3200 123.6 84.67 70.5 30.13 6400 127.4 86.56 73.4 34.15 12800 129.7 88.28 74 6 39-01 25600 135-0 87.42 74.8 43.62 51200 154-4 90.8 72.4 46.31 30 Table XXXVII. Dissociation of Potassium Iodide in Mix- tures of Methyl Alcohol and Water at o. V. per cent. 25 per cent. 50 per cent. 75 per cent. 100 per cent. 1024 98.4 ioo. o 94.2 ioo. o 97.8 2048 99.2 ... 95.0 ... 100.0 4096 100.0 ... 98.7 8192 ... ... 100.0 Table XXXVIII. Dissociation of Potassium Iodide in Mix- tures of Ethyl Alcohol and Water at o. V. per cent. 25 per cent. 50 per cent. 75 per cent. 100 per cent. 1024 98.4 98.7 93.9 95.8 71.5 2048 99.2 100.0 98.1 99.5 &7-4 4096 loo.o loo.o 100.0 100.0 90.0 8192 ... ... ... ... 100.0 Table XXXIX. Dissociation of Cobalt Chloride in Mixtures of Methyl Alcohol and Water at o. V. per cent. 25 per cent. 50 per cent. 75 per cent. 100 per cent. 1600 100.0 88.6 ... 84.5 87.6 3200 ..'. 90.3 ... 95-i 95-5 6400 91.9 96.5 99.6 12800 100.0 100.0 100.0 Table XL. Dissociation of Cobalt Chloride in Mixtures of Ethyl Alcohol and Water at o. V. per cent. 25 per cent. 50 per cent. 75 per cent. 100 per cent. 1600 100.0 94.2 92.5 93.0 63.2 3200 ... 96.6 95.7 94.1 72.0 6400 ... 100.0 97.0 96.2 8 i. 2 12800 ;, ; 100.0 97.9 92.5 25600 ,.* ... ... 100.0 92.2 5I2OO v. . ... ... ... IOO.O Table XLI. Maxima in Molecular Conductivity for Certain Salts in Pure Alcohols. 0. 25. KI in methyl alcohol (77-5) (112.6) KI in ethyl alcohol 32.7 47 . 5 NH 4 Br in methyl alcohol 71.8 96 . 8 NH 4 Br in ethyl alcohol (30. 3) 39.6 KCNS in methyl alcohol (69 . 2) (110.4) KCNS in ethyl alcohol 29.2 46 . 7 LiNOg in methyl alcohol 61.5 (96 . 7) IyiNO 3 in ethyl alcohol 25.9 40 . 8 Nal in methyl alcohol 64. i 91 .9 Nal in ethyl alcohol 27.0 42.8 CuCl 2 in methyl alcohol 91.3 116.4 CuCl 2 in ethyl alcohol (25.7) (32.7) Ca(NO 3 ) 2 in methyl alcohol Ca(NO 3 ) 2 in ethyl alcohol CoCl 2 in methyl alcohol 116.2 166 . o CoCl 2 in ethyl" alcohol 31.6 (46 . 7) Table Solvent. 53 949 55-352 61.195 52.842 57.480 55.686 54-510 59-798 55 546 53-215 Boiling-Point Data. XLI I. Sodium Iodide in Methyl Alcohol. Concen- tration. 0.03478 0.03300 O.O279O 0.02661 0.02560 0.02108 O.O2268 o . 02005 O.OI42I O.OI2II Salt. 2.8I3I 2-7357 2-5597 2 . 1082 2 . 2O6O 1.7227 1.8380 I. 8080 I 1943 0.9665 Rise. 0.429 0-425 0.3556 0-347 0.318 0.263 0.298 0.251 0.178 0.155 Molecular rise. 12-33 12.90 12.74 13.04 12.42 12.50 I3-I4 12.52 12.52 12. 80 Dissocia- tion. 46.8 53-6 51-8 55-2 47-8 48.8 56.4 49-o 49-o 52-4 Solvent. 53 I0 54-734 64.744 53-896 61.293 55-509 61 .701 59-294 54-368 64.926 Table XLIII. Salt. 3-I7I5 2.7683 3 . 2084 2.6133 2.5117 2.0431 2.1323 i . 9686 1-5300 1.4171 -Sodium Concen- tration. 0.03984 0.03374 0.03303 0.03235 0.02730 0.02455 O.O23O6 O.O22I4 0.01877 0.01455 Iodide in Ethyl Alcohol. Molecular rise. 14.63 Rise. 0.585 0.512 0-495 0.481 0.402 0-365 o.35i 0.327 0.281 0.223 Dissocia- tion. 14.98 14.87 14-73 14.86 15.22 14.76 14.97 I5-32 27.7 31-9 30.2 29-3 28.0 29.1 32-3 28.3 30.1 33-2 32 Table XLIV. Calcium Nitrate in Methyl Alcohol. Concen- Molecular Dissocia- Solvent. Salt. tration. Rise. rise. tion. 56 . 762 1-4954 O.OI685 o. 160 9.969 9-5 64.823 1.2154 O.OII42 0.107 9.366 8.6 52.567 0.9792 O.OII35 o. 106 9-340 6.8 63-825 1.2489 O.OII3I O.IIO 9-725 7.9 62.275 0-7453 O.OO729 0.073 IO.OO9 9-3 Table XLV .Calcium Nitrate in Ethyl Alcohol. Solvent. 50.476 54-301 52.355 Salt. I . IOO4 1-3570 0.6795 Concen- tration. O.OI328 0.01228 O.O079I Rise. 12.68 12.86 12.51 Molecular rise. 0.168 1.158 0.099 Dissocia- tion. 5-i 5-9 4-4 Table XLVI. Cadmium Iodide in Ethyl Alcohol. Concen- Molecular Dissocia- Solvent. Salt. tration. Rise. rise. tion. 48.831 3-59I5 0.02007 0.253 12. 60 4.8 54-657 3.6962 0.01850 0.230 12-43 4-05 50.956 3.1632 0.01694 0.214 12.63 4-9 51-574 2.9277 0.01549 0.195 12.58 4-7 52.348 2.7683 0.01443 0.181 12-57 4-6 52.316 2.6784 0.01397 o. 176 12.58 4-6 48.034 2.U37 O.OI2OI 0.152 12.67 5-o 51.668 I.249I o . 00660 0.082 12 .42 4.0 56 563 O.87I2 o . 04204 0.052 12.38 4-3 DISCUSSION OF RESULTS. Tables I to XVI show the conductivity of the various salts worked with in the pure solvents at both o and 25. Nine of these tables show a maximum either at one or both tem- peratures. The other tables show no maximum up to the highest dilutions measured. In several cases maxima occur at one temperature and none at the other. In some tables the maxima occur at the same concentration at both tem- peratures ; in others at different concentrations, but they always occur at concentrations which are close together. The tem- 33 perature coefficients in general agree very well. Nearly all show a slight increase with increasing dilution. Tables XVII to XXVIII show the conductivity of potas- sium iodide and cobalt chloride in mixtures of methyl alcohol and water at both o and 25. In some of these tables the maximum conductivities are reached. The maxima generally occur at a greater concentration at o than at 25. In a few tables the maxima occur at the same concentration at both temperatures. In nearly every case where there is a maximum there is a slight decrease in conductivity, then a rapid increase as dilution increases, thus giving an inflection in the curve. Figs. II to IV give the curves for the conductivities of potas- o 25 50 75 xoo Fig. II. Conductivity of potassium iodide in mixtures of methyl alcohol and water atO. 34 slum iodide in mixtures of methyl alcohol and water and of ethyl alcohol and water. The abscissas represent the per- centage of alcohol and the ordinates represent the conductiv- 140 130 no 100 80 70 o 25 50 75 100 Fig. III. Conductivity of potassium iodide in mixtures of methyl alcohol and water at 25. ity. In Fig. II there is a marked minimum with 50 per cent, methyl alcohol. Fig. Ill shows a minimum with 75 per cent, methyl alcohol. Fig. IV for potassium iodide in methyl alcohol-water mixtures shows the same characteristics. Fig. 35 V shows a minimum for only three concentrations ; these are with 75 per cent, ethyl alcohol. Figs. VI to IX are the curves for the conductivity of cobalt chloride in methyl alcohol-water mixtures and ethyl alcohol- water mixtures at both o and 25 . Fig. VI shows a minimum 20 o 25 50 75 XOO Fig. IV. Conductivity of potassium iodide in mixtures of ethyl alcohol and water at 0. with 50 per cent, methyl alcohol. Fig. VII shows minima in the curves with 75 per cent, methyl alcohol. In Figs. VIII and IX there is no minimum. Tables XIXX to XXXVI represent the values for the con- ductivities of potassium iodide and cobalt chloride in mixed solvents, arranged according to temperature. The propor- 100 70 60 40 o 25 so 75 ioo Fig. V. Conductivity of potassium iodide in mixtures of ethyl alcohol and water at 25 . tions in which the solvents are mixed and the concentrations vary. A study of the maxima of conductivity in these tables is interesting. The more probable values for /* < are indicated by a (*). By means of these values I have calculated the dis- 37 sociation of the salts at different volumes for four of these tables (XXIX, XXXI, XXXIII, and XXXV) , since these present more / oo values than the rest. I have used the well-known equa- o 25 50 75 100 Fig. VI. Conductivity of cobalt chloride in mixtures of methyl alcohol and water at 0. tion, a = and the values for a are given in Tables XXXVII to XL. In Table XXXIII no /ceo occurs for 50 per cent, methyl alcohol- water mixtures. These values for dissociation are interesting when com- pared with the values for the corresponding molecular conduc- 38 tivities. Fig. X gives the curves for dissociation corresponding to the molecular conductivity as indicated by the curves in Fig. IV. Fig. XI in the same manner corresponds to Fig. VI and Fig. XII to Fig. VIII. 100 o 25 so 7 100 Fig. VII. Conductivity of cobalt chloride in mixtures of methyl alcohol and water at 25. In Fig. IV the conductivity curves of potassium iodide in ethyl alcohol- water mixtures at o show minima for all dilu- tions, while the corresponding curves for dissociation in Fig. X at first rise. If the equation a = holds for mixed sol- 39 vents this would indicate that at o the dissociation in 25 per cent, ethyl alcohol-water mixtures is slightly greater than in pure water. In all mixtures the dissociation is very much greater than it is in pure alcohol. 10 o 25 50 75 ioo Fig. VIII. Conductivity of cobalt chloride in mixtures of ethyl alcohol and water at 0. Fig. XI gives the curves for cobalt chloride in methyl alco- hol-water mixtures corresponding to the molecular conduc- tivity as represented by Fig. VI. The curves for dissocia- 40 tion r show minima, but the drop below the straight line of averages is very small when compared with the large and decided minima in Fig. VI. 160 140 80- 40 o 25 50 75 100 Fig. IX. Conductivity of cobalt chloride in mixtures of ethyl alcohol and water at 25 *. Fig. XII for dissociation corresponds to Fig. VIII for molec- ular conductivity. The relation between these two figures is similar to the relation between X and IX. In both cases the mixed solvents are ethyl alcohol and water. In this case we have a binary salt, and the curves for Figs. X and XII are strikingly similar. o as So 75 zoo Pig. X. Dissociation of potassium iodide in mixtures of ethyl alcohol and water at 0*. The curves representing dissociation in ethyl alcohol-water mixtures are sometimes upward curves, taking a direction oppo- 110 00 80 I I I o 25 50 75 too Fig. XI. Dissociation of cobalt chloride in mixtures of methyl alcohol and water at 0*. site to that of the curves representing conductivity, which are downward curves. This fact is especially apparent when Fig. IV, 42 giving the curves for the conductivity of potassium iodide in mixtures of ethyl alcohol and water at o, is compared with Fig. X, which gives the curves for the dissociation of these same solutions. This plainly indicates that the greatly dimin- ished conductivity in mixed solvents is due not to diminished dissociation but to the other factor conditioning conductivity, viz., diminished velocity of the ions through the solution. Though it had been previously pointed out that this diminished 80 60 o 25 50 75 ioo Fig. XII. Dissociation of cobalt chloride in mixtures of ethyl alcohol and water at 0. conductivity is due almost entirely to increased viscosity of the mixed solvent, it was not definitely known what the magnitude of the dissociation in these mixed solvents is, nor was it sus- pected that this dissociation might be greater in the mixed than in the pure solvents, as is shown to be the case by the curves for dissociation, some of these curves having maxima while those of conductivity have decided minima. These facts are quite marked where ethyl alcohol-water mixtures are used 43 as solvents. In such cases the increased viscosity, on the one hand, diminishes the conductivity, and the decreased dissocia- tion, on the other, increases the conductivity. The viscosity in this case, since it is the more potent factor, causes the large minima in the curves for conductivity. These minima would be more marked than they are were it not for the slightly increased dissociation. Table XU gives the /*> values of molecular conduc- tivity for the various salts studied both in methyl and in ethyl alcohols at o and at 25, whenever such values could be found. The values without the brackets were determined experimentally. Those within the brackets could not be determined experimentally because of the great dilutions and consequently unavoidable errors, but were calculated by a method given below. An examination of the table reveals the fact that there is some relation between the maximum for each salt in the differ- ent solvents at any given temperature. It was suspected that this relation is a constant and that the following equa- tion would hold : ^oo methyl constant. ,. J" oo ethyl This equation was then applied with the following results: Binary Electrolytes. LiNO 3 at o =2.37. Nal o = 2.37. NH 4 Br 25 =2.44. Nal 25 =2.17. Ternary Electrolytes. CoCl 2 ato =3.68. These facts make it appear probable that there is approxi- mately such a constant for binary electrolytes and another for ternary electrolytes. These data are not sufficient, however, to give a final value to such constants. Further investigations will be required for this purpose. Most of these maxima occur 44 at dilutions of V = 12,800 to V = 51,200. At these dilutions it is very difficult to obtain accurate results and the values for the constant are probably within the limits of experimen- tal error. The value for the constant between methyl and ethyl alcohols for binary electrolytes appears to be very nearly 2 .37. I have obtained but one value for ternary electrolytes, which is 3.68. That is nearly 1.5 X 2.37. The latter value (3.56) is probably the more nearly correct. The factor i . 5 is em- ployed -since this expresses the ratio of ions present between binary and ternary electrolytes at complete dissociation. With the data in hand I proceeded to test further the accuracy of the above equation by supplying by calculation in Table XU those // values which could not be deter- mined experimentally. The value of the constant was taken as 2.37 for binary electrolytes and 3,56 for ternary electrolytes. The calculated value for potassium iodide in methyl alcohol at o from the value in ethyl alcohol would be 77.5. An ex- amination of Table I reveals the fact that this value is proba- bly very nearly correct. For 25 it would be 112.6. Again from the same table this is probably correct. Ammonium bro- mide in ethyl alcohol at o would be equal to 30. 3. This too as indicated by Table IV is probably nearly correct. Potassium sulphocyanate in methyl alcohol at 25 would have a value of 110.4. Table V indicates that this value is probably correct within the limits of experimental error. Lithium nitrate gives a value of 96.7 in methyl alcohol at 25; compared with Table VII this would seem to be nearly correct. With ternary electrolytes there are only three cases to which this equation can be applied. Copper chloride in ethyl alco- hol at o would give a value of 24.8, and cobalt chloride in ethyl alcohol at 25 would give 46.7 as the value for the maximum in conductivity. In Table XIV, at o, a maximum is reached at V = 25600. The maxima at the different tem- peratures as a rule do not occur very far apart. We believe that the value 46 . 7 is pretty nearly correct for the maximum for cobalt chloride in ethyl alcohol at 25. The only two values which do not fit into the table are the value for potas- 45 slum cyanide in methyl alcohol at o and that for copper chloride in ethyl alcohol at 25. The latter, however, is not far from what we might expect it to be. I believe from the above results that the ratio between the maxima in molecular conductivity for different salts in methyl alcohol and the maxima for the same salts in ethyl alcohol is probably constant for all binary electrolytes, that for all ternary electrolytes it is a constant of different value, and that there is a definite relation between these two constants. Jones, in an article on "The Electrolytic Dissociation of Certain Salts in Methyl and Ethyl Alcohols, as Measured by the Boiling-Point Method," gives the following table which expresses "the dissociation values of the above alcohols as calculated from data obtained by the boiling-point method." The ratios of these values were calculated and are also ex- pressed in the table : Table XLVIL Dissociation Dissociation Ratio. 2.08 1.8 2-5 2-3 2-3 2.7 3-o Leaving out the value 1.8 for sodium iodide, which is evi- dently erroneous, we obtain as a mean from the other values of the binary electrolytes 2.37 which, it will be remembered, is the same as the value obtained above by the conductivity method for the ratio between the maxima in the different alcohols. The value in this table for the one ternary electro- lyte is not so great as that determined by the conductivity method, and yet it is possible that more data would give comparable values. The boiling-point data in this work were obtained by means in methyl Dilution alcohol. in ethyl alcohol. Substance. normal. Per cent. Per cent. KI 0. 52 25 Nal O. 60 33 NaBr 0. 60 24 NH 4 Br 0. 49 21 CH 3 COOK O. 36 16 CH 3 COONa 0. 38 14 Ca(N0 3 ) 2 0. 15 5 4 6 of the boiling-point apparatus used by Jones. 1 Both solvents were carefully purified and dried. Table XUV gives thelksociation of certain salts as cal- culated by both the conductivity and boiling-point methods: Table Dissociation from Dissociation from conductivity boiling-point method. method. Salt. Solvent. Per cent. Per cent. KI Methyl 65 49 KI Ethyl 49 26 Nal Methyl 75 61 NH 4 Br Methyl 71 47 NH 4 Br Ethyl 40 20 It will be seen at a glance from the above table that the dis- sociation values as determined by conductivity are higher than those found by the boiling-point method, in both methyl and ethyl alcohols. This may possibly be due to a poly- merization of the undissociated molecules in the solvent in question. This would give too low dissociation as measured by the boiling-point method, since this method takes into ac- count both the molecules and the ions, while the conductivity method deals only with the ions. SUMMARY. I have measured the conductivity of various salts in pure methyl and ethyl alcohols at very high dilutions, and also in mixtures of methyl and ethyl alcohols with water. In many of these measurements I have found the value of H&. Many of these values were found to occur at concentra- tions between V = 3200 and V = 51200. A constant ratio was found between the values of // for several binary electrolytes in methyl alcohol and in ethyl alcohol, and the ratio for one ternary electrolyte was worked out. These facts indicate that there is a definite relation between these two ratios. I have found minima in most of the curves for mixed solvents. I have tabulated the dissociation of several salts in methyl alcohol and ethyl alcohol as determined by the boiling-point method. * Z. physik. Chem.. 31, 114 (1899) (Jubelband zu van't HoffV BIOGRAPHY The author of this dissertation, Henry Royer Kreider, was born near Millheim, Pennsylvania, April 24, 1874. His pre- paratory training was received in the public schools and in the Spring Mills Academy. He entered Franklin and Marshall College in 1894 from which he received the degree of A.B., in 1898, and A.M., in 1901. Since then he has taught in differ- ent schools and academies. The year 1904-5 was spent in graduate 'work at the Johns Hopkins University. After teach- ing for several years in the Pennsylvania State-Forest Academy he again entered the Johns Hopkins University in 1907. For several years since then a part of the time was devoted to teaching. UNIVERSITY OF CALIFORNIA LIBRARY BERKELEY Return to desk from which borrowed. This book is DUE on the last date stamped below. '* - <& .. LD 21-100m-ll,'49(B7146sl6)476 Stockton, Calif. T. M. Reg. U.S. Pat. Off. THE UNIVERSITY OF CALIFORNIA UBRARY