50 Dr. G. Gore on a Method of Measuring 



was produced by heating and then cooling the liquid, and was 

 greatest with bromine and least with iodine. 



The electromotive force at 17° C, in a solution of 35'5 

 grains of chlorine in 511,500 grains of water, of a voltaic 

 couple of magnesium and platinum was 2'6124, and of 

 aluminium and platinum 1*553 volt. 



Relations of Electromotive Force to Dilution and Specific 

 Gravity of Electrolytes. 



In a previous research on " Relation of Volta Electromotive 

 Force to Latent Heat, Specific Gravity, &c. of Electrolytes " 

 (Philosophical Magazine, August 1891, p. 157), the results 

 obtained by diluting about twenty different liquids showed an 

 increase of mean amount of electromotive force in nearly all 

 cases; and that if the amounts of such change were arranged 

 in the order of their respective magnitudes, all the strong 

 acids were at one end of the series, all the alkalies at the 

 other, and the neutral salts in the middle, thus forming a kind 

 of volta-tension series. Dilution of strong solutions of acids 

 largely increased, and of those of alkalies only feebly in- 

 creased, the mean amounts of their volta-electromotive force. 



With regard to any relation of volta-electromotive force to 

 specific gravity, in cases of chemical union, various investi- 

 gators have already shown that contraction of total volume of 

 the ingredients nearly always occurs, and that it is usually 

 attended by evolution or loss of heat ; and the results of the 

 present research show that these effects are very generally 

 accompanied by decrease of mean amount of electromotive 

 force. But in cases of mere dilution, the increase of mean 

 specific gravity which usually takes place is nearly always 

 attended by increase of mean electromotive force. 



Remarks and Conclusions. 



The following are the chief results obtained in this 

 research : — 1st. In every instance either a loss or gain of 

 electromotive force occurred during the mixing of any two 

 electrolytes. 2nd. The amount of loss or gain differed in 

 every different case, and depended upon the nature of 

 each of the constituents of the mixture, the kind of positive 

 metal, and the degree of concentration and temperature of the 

 liquid. 3rd. The loss or gain of mean amount of elec- 

 tromotive force coincided with the presence or absence of 

 chemical change. The amounts of loss and the proportion of 

 number of cases of loss are largest in Section A, in which 

 the degree of chemical action is the greatest, and in Section J, 



