﻿336 Intelligence and Miscellaneous Articles, 



This value is quite of the order of the value above given for 

 hydrogen A H <1'1 x 10 13 , and that for iodine- vapour Ai =1-2 x 10 12 

 ergs ; it is indeed somewhat greater than the latter. 



Prom this it results that the whole work required for the dissocia- 

 tion of hydrogen and iodine molecules is used in overcoming the purely 

 electrical attraction forces of the valency-charges. 



That this heat of dissociation is so completely spent in elec- 

 trical work shows, in agreement with many other facts, that the forces 

 of chemical affinity are essentially of an electrical character ; that the 

 electrostatical forces which the charges exert on each other at the 

 positions of valency are " by far the most powerful among the forces 

 exerted among the atoms : " and that in H. v. Hemholtz's ' Faraday 

 Lectures/ particular possible chemical forces of the charged atoms can 

 be but infinitely small in comparison with electrical forces. This 

 seems of great importance for the theory of chemical forces in 

 general. — Wiedemann's Annalen, No. 10, 1893. 



ALTERATIONS OF THE ELECTRICAL RESISTANCE OF AQUEOUS 

 SOLUTIONS AND OF GALVANIC POLARIZATION WITH PRESSURE. 

 BY BRUNO PIESCH. 



A large series of liquids were investigated, both acids and solu- 

 tions of salts. The method of measurement was such that the 

 resistance and the polarization could be determined simultaneously. 



The great pressure was produced by a Cailletet's apparatus, 

 which held up to 600 atmospheres. The resistance-vessels con- 

 sisted of a combination of glass tubes, which could be connected 

 externally by means of ebonite cemented in the metal cap, which 

 was firmly screwed in the iron cylinder. 



The measurements gave the* following results : — 



Change of pressure produces a change of resistance, which 

 decreased in all cases with increase in the pressure. Xo regular 

 influence of concentration could be observed, but with most sub- 

 stances the variations of a less concentrated solution w T ere greater 

 than of a concentrated solution. 



As the pressures increased the decreases of resistance were less. 

 Polarization also showed a change of value with higher pressure. 

 These, however, are for the most part small. An increase of 

 polarization with the pressure was in general observed. The 

 irregularities here shown were greater than with the measure- 

 ments of resistance. 



In conclusion, a solution of NH i N'0 2 in alcohol was investi- 

 gated, and alterations in the same direction were here met with. — 

 Wiener Berichte, May 25, 1894. 



