146 Intelligence and Miscellaneous Articles. 



For the sake of comparison with experiment, the influence of 

 temperature on the coefficient of diffusion is taken into account 

 on the basis of the theory of dissociation : the coefficients 0*026 for 

 salts and 0*024 for acids and bases represent the alteration of 

 conductivity with temperature ; these numbers are found to agree 

 very well with the observations of de Heen and Schumeister. 



The coefficients of diffusion reduced to 18° agree very well with 

 the observations of various experimentalists, as shown in the table 

 given ; and this agreement is an excellent proof of the validity of 

 the author's consideration. 



From the same point of view the author treats the diffusion of a 

 mixture of salts, as well as of electrolytes at greater concentration. 

 He shows further, how in the same way the difference of electrical 

 potential between solutions of different concentration may be 

 calculated. Between two places of a solution in which the osmotic 



pressure is p, and «?„, the difference of potential is p log -o. 



u -f v p 2 



Zeitschrift fur pliys. Chemie [2] vol. ii. p. 613 ; Beibldtter der 



Physih, vol. xiii. p. 131. 



ON THE MOLECULAR CONDITION OF DISSOLVED IODINE. 

 BY MORRIS LOEB. 



By means of a determination of the vapour tensions, the author 

 endeavoured to determine whether iodine in its brown solution is in 

 a different molecular condition to that of its violet solution. 

 Ether was used as a solvent for the brown, and bisulphide of carbon 

 for the violet. The measurement of the tension was effected by 

 means of a Begnault's apparatus, suitably modified. A trial of its 

 applicability, by means of solutions of naphthaline &c. in ether and 

 in bisulphide of carbon, gave satisfactory results, since the molecular 

 weights 132 and 127*5 were obtained instead of 128. The mode 

 of calculation is given in the original. For solutions of iodine in 

 bisulphide of carbon, the median values of the separate series of 

 experiments varied between 264 and 326*6, the general mean was 

 found to be 303*25. For molecules of the composition I 2 the 

 molecular weight is calculated at 254, and for I 3 at 381; the 

 number obtained is about the mean of these. 



The solution of iodine in ether also gave very divergent values 

 for the individual series of experiments, as they varied between 

 466*1 and 577*2, while the general average 507*2 agrees almost 

 entirely with the value 508 required for I 4 . The existence of the 

 molecules I 4 appears therefore probable for the brown modifica- 

 tion. 



Experiments made to determine the question by means of 

 Kaoult's freezing-point method were unsatisfactory, for within the 

 limits caused by the difficult solubility of iodine the errors of 



