developed during the Combination of Zinc and Iodine. 295 



The free iodine present was estimated with standard hypo- 

 sulphite solution in the usual way. 



This table requires no particular remark. 



(5) Three determinations of the variation of the electro- 

 motive force of the zinc-iodine cell were made, due to varying 

 the strength of the iodide of zinc, one in an iodine solution 

 in distilled water, one in a zinc-iodide solution of medium 

 strength, and one in a saturated iodide of zinc solution. The 

 results are to be found in the Table (c)*. 



If these numbers are subtracted from those obtained for 

 corresponding solutions in the cuprous-iodide cell, the 

 numbers obtained show that the curve for the zinc-iodine cell 

 is slightly different, rising a little higher for distilled water, 

 and not falling quite so low for saturated iodide of zinc. 



Table (a). — Variations in Electromotive Force caused by 

 varying the Zinc Iodide in solution as measured in the Zinc- 

 Cuprous-Iodide Cell. 



Electromotive Force in Volts. 

 •390 

 •415 

 •419 

 •425 

 •440 

 •454 

 •488 

 •545 

 •607 

 •637 

 •656 

 •696 

 •771 

 •894 



Grms. of Znl 2 in 1 grm. 

 " 3-90 

 3-90 

 3-64 

 2*87 

 2-72 

 2-49 

 1-86 

 •596 

 •236 

 •118 

 •059 

 •029 

 •003 

 D.W. 



of Water. 



Table (b). — Variations in Electromotive Force caused by 

 varying the amount of Iodine dissolved in a solution con- 

 taining '33 grm. of Znl 2 in 1 grm. of water. 



Electromotive Force in Volts. 



Grms. of Iodine in 1 c. c. 



1-287 



•309 



1-271 



•155 



1-271 



•077 



1-268 



•037 



1-259 



•018 



1-238 



•005 



1-221 



•0006 



* Very similar results have been obtained for sulphates and chlorides 

 by Alder Wright, Phil. Mag. 1884. 



