Constitution of Isomeric Solutions. 299 



The mixture "A" therefore slowly altered in chemical con- 

 stitution at ordinary temperatures towards that of " B." The 

 one "B" did not change under these conditions. 



Influence of Heat. 



Mixture "A." 



Experiment 8. — Dilute solutions of sodium sulphate and 

 nitric acid were mixed, and the mixture, containing 1 grain 

 of substance in 1550 grains of water, and giving, after the 

 necessary further dilution, the usual average amount of voltaic 

 energy, viz. about 77,000, was heated during two minutes to 

 100° C. in a closely stoppered glass flask, then cooled, agitated, 

 and its amount of energy measured ; it was 



Between 30,511 and 33,917 at 15° G. Average 32,214. 



The mixture was therefore an unstable one, and its voltaic 

 energy was rapidly and largely reduced by rise of tem- 

 perature. 



Experiment 9. — The solution of the same mixture, contain- 

 ing 1 grain of substance in 15*5 grains of water, the energy 

 of which had already been reduced to 32,214 by insufficient 

 dilution during its preparation (Exp. 4), was heated exactly 

 the same as in Exp. 8 ; it then gave 



Between 30,511 and 33,917 at 15° 0. Average 32,214. 



Its voltaic energy therefore was unaffected. 



Experiment 10. — In order to diminish the amount of che- 

 mical change which took place during the mixing of the 

 ingredients of U A," very dilute solutions of them were taken 

 and cooled to 3° C. immediately before mixing. The mixture 

 contained 1 grain of substance in 15,500 grains of water. 

 Its amount of voltaic energy was 



Between 91,176 and 100,650 at 11° C. Average 95,913. 



The lower temperature therefore diminished the amount of 

 chemical change which occurred during the mixing (compare 

 Exp. 4). This shows that under the ordinary conditions of 

 temperature, when making the mixture "A ;; some decom- 

 position occurred. 



Experiment 11. — A precisely similar experiment was made 

 with less diluted ingredients, forming a mixture of 1 grain 

 of substance in 155 grains of water. Its amount of energy 

 was 



Between 30,511 and 33,917 at 11° C. Average 32,214. 



The influence of the lower temperature therefore in this 

 case was insufficient to neutralize that of stronger solution, 



