10 INTRODUCTION. 



values than others, thus causing the fluctuations in the value of the product. It 

 must be borne in mind that conductivity measurements at dilutions so great (400,000 

 liters) that the correction for the conductivity of the solvent often amounts to more 

 than 50 per cent of the total, are being made at a point where the method is taxed 

 rather beyond its limitations; and it is not surprising that, even with the utmost pre- 

 cautions, concordant results were not obtained. The failure of cadmium iodide to 

 follow the behavior of lithium nitrate in very dilute solutions is merely negative 

 evidence, and must be weighed as such. 



Some boiling-point determinations of cadmium iodide in acetone were made, and 

 here, too, considerable polymerization was found. In a 0.09 normal solution the 

 indicated molecular weight was 448, calculated 364. 



Thus, the apparent exceptions to the relations found by Jones and his coworkers 

 are seen to vanish when we are dealing with what are practically infinitely dilute 

 solutions. The investigations have dealt with twelve electrolytes and six solvents, 

 and in every instance the same relations were found to hold, connecting the molecu- 

 lar conductivity with the fluidity. 



Jones and Mahin 1 also made a study of the conductivity and viscosity of lithium 

 nitrate in ternary mixtures of the four solvents used above. The results were about 

 what would be expected from a knowledge of the solutions in binary mixtures. The 

 conductivity curves, in the great majority of cases, followed the fluidity curves, and 

 no new relations were brought to light. 



As a result of this work, we may make the general statement: If we mix methyl 

 and ethyl alcohols, or methyl alcohol and acetone, the conductivity curves are very 

 close to straight lines, and the fluidities of the mixture are nearly additive. Take, 

 for instance, the last case mentioned. Table 1 shows the fluidities of various mix- 

 tures of methyl alcohol with acetone at 0, as determined by the viscosimeter, and 

 also as calculated from those of the two components. 



Table 1. Fluidity of Mixtures of Methyl Alcohol and Acetone at 0. 



The observed fluidities are very nearly the averages corresponding to the different 

 mixtures. On the other hand, if we mix water with the alcohols, or with acetone, 

 there is interaction between the components of the mixture; and certain of its phys- 

 ical properties are found no longer to bear simple relations to the properties of the 

 single solvents. Otherwise expressed, the law of averages is not followed, and the 

 properties of the mixture are not additive. Hence, we may conclude that water, 

 mixed with the other three solvents, causes some deep-seated change in the state of 

 molecular aggregation of the liquid molecules, while mixing the three organic sol- 

 vents with each other causes no such change. The various mixed solvents may 

 therefore be divided into two classes, those not containing water with properties 

 nearly or quite additive, and those containing water with properties that are not 

 the averages of the two components. 



'Amer. Chem. Journ., 41, 433 (1909). 



