1888.] and the Minimum-point, fyc, of a Voltaic Couple, 307 



Table XVI.— Ditto at 13° C. 



Grains. 



Volts. 



Grains. 



Volts. 



Grains. 



Volts. 



0-03 

 0-027 



2 -2261 

 2-1317 



0-018 

 0-015 



1 -8457 

 1-84 



0-006 

 0-003 



1 -7748 



n 



0-024 

 021 



2 -0459 

 1 -9716 



0-012 



0-009 



1*817 

 1-7748 



0-0000003 

 water 



118 

 1 088 



Table XVII.— Ditto at 13° 0. . 



Grains. 



Yolts. 



Grains. 



Volts. 



Grains. 



Volts. 



0-003 

 -0015 

 -00075 

 -000375 

 0-0001875 



1-7748 

 1 -6604 

 1 -6318 

 1 -5346 

 1 -4316 



0-0000937 

 0-0000468 

 0-0000234 

 00001172 

 0-00000585 



1-4173 

 1-403 

 1 -3887 

 1 -3744 

 1 -3605 



-00000293 

 -000001464 

 -000000732 

 water 



1-26 

 1 -2457 

 1-1799 

 1 -0884 



Table XVIII.— Ditto in 13,950 grains of Water at 11° C. 



Grains. 



Volts. 



Grains. 



Volts. 



00001247 



1-1313 



00000713 



1 -0884 



-00001104 



1 -0998 



0-000003565 



» 



00001069 



1 -0884 



water 





-0000089 









The mode by which the chlorine-water was prepared and its strength 

 ascertained has been already described (' Roy. Soc. Proc.,' vol. 44, 

 1888, p. 151, 'Nature,' vol. 38, p. 117). The minimum proportion 

 of chlorine necessary to upset the balance was found more nearly by 

 adding very small quantities of an exceedingly dilute solution of it 

 to the water until the required strength was attained, thus avoiding 

 the risk of error attending more numerous dilutions. The proportion 

 lay between 1 in 1264 million and 1300 million parts of water. The 

 variation of electromotive force by uniform increase of the strength 

 of the solution was irregular. 



The following are the minimum proportions of iodine, bromine, and 

 chlorine, arranged for comparison : — 



