112 



Van Name and Brown — Tri-Iodide and 



bisulphide. Here x is evidently equal to the solubility of 

 iodine in pnre water (0*00132 mols/ liter at 25°, according to 

 Bray*) so that the presence of a carbon bisulphide phase could 

 give no further information. In these cases the bottles, which 

 contained a little solid iodine, were rotated in the thermostat 

 for 48 hours before analysis, and the liquid was forced into 

 the pipettes by air pressure through an asbestos filter contained 

 in a narrow glass tube. 



The tables call for little further explanation. It must be 

 borne in mind that electrolytic dissociation is disregarded in 

 calculating the constant K^. The columns headed (Ij, concen- 

 tration of uncombined iodine in the water solution, (21), con- 

 centration of uncombined iodide, and (2I3), concentration of 

 tri-iodide, are given in only a few cases, since these three quan- 

 tities (or their equivalents for bromine) are only derived values, 

 and can be easily calculated if needed by means of the equa- 

 tions 



(^I) + (2I3) = na 



{%\;) = b - X 

 (IJ =x = g/c 



All concentrations in the tables, where not otherwise stated, 

 are in millimols or milli-formula weights per liter. The values 

 of ^1, however, are those calculated in the usual way, in terms 

 of mols per liter. A few obviously faulty values of K^^ indi- 

 cated by enclosure in parentheses, have been omitted in cal- 

 culating the averages. 







Table IY. 











Nickel Iodide. 







1. a = 



0-3715 molar Nil2 + 0-0148 



2. a = 0-1366 molar Nil, + 0-00425 





molar 



HI. 





molar HI. 



(21) 



-}-(2l3) = 0-7577 molar. 



(2I) + (2l3) = 



•2775 molar. 



6 



g 



c K, 



b 



Q 



c K, 



108-1 



116-7 



585 0-00120 



68-9 



259-9 



595 0-00133 



67-7 



66-1 



582 0-00116 



46-32 



158-8 



587 0-00136 



32-24 



31-87 



580 0-00124 



27-77 



90-4 



585 0-00140 



19-48 



30-19 



580 (0-00198) 



14-26 



61-1 



580 (0-00196) 



15-98 



16-87 



580 0-00135 



7-36 



23-39 



580 0-00148 



8-99 



9-13 



580 0-00131 



3-919 



11-14 



580 0-00135 



7-13 



6-99 



575 0-00128 



2-460 



7-94 



575 0-00155 



4-47 



4-38 



575 0-00129 



1-636 



5-68 



575 (0-00168) 



2-190 



2-982 



575 (0-00179) 



1-165 



3-357 



575 0-00139 





mean 0-00126, 





mean 0-00 1 40^ 



* Jour. Am. Chem, Soc, xxxii, 936, 1910. 



