Tri-Bromide Equilibria. Ill 



allowed to stand in the thermostat until the two layers had 

 separated and become entirely clear. Finally, samples of each 

 layer were taken with carefully calibrated pipettes and the con- 

 centration of the halogen determined by titration with thiosul- 

 phate. In the case of the bromine solutions the pipettes were 

 not filled by suction, but by applying air pressure to the bot- 

 tle, and the samples were run into an excess of potassium iodide 

 solution before titrating. In the following tables the concentra- 

 tions so found are given in the columns headed 5 and g^ the 

 former referring to the aqueous and the latter to the non-aque- 

 ous layer. These values together with a, the initial concentra- 

 tion of the halide, and c, the distribution coefficient, furnish all 

 that is needed for the calculation of K^ from Equation III, 

 since x in that equation is mereh^ q/c. For c we have used 

 throughout values determined by Jakowkin, or derived from 

 Jakowkin's results by graphic interpolation. 









Table III 



.. 













Strontium Iodide. 







1. a = 0-1312 molar Sris. (^I) + 



(2I3) = 2a 



— 0-2624 molar. 



6 



Q 



c 



X 



(2I3) 



(21) 



^1 



63-65 



257-3 



590 



0-4360 



63-2 



199-2 



0-00137 



38-24 



137-5 



580 



0-2371 



38-00 



224-4 



0-00140 



22-63 



76-9 



578 



0-1331 



22-50 



239-9 



0-00142 



14-07 



46-5 



578 



0-0805 



13-99 



248-4 



0-00143 



8-84 



28-31 



578 



0-0490 



8-79 



253-6 



0-00141 











mean 



0-00140g 



3. a = 0-0328 molar Srl2. (21) + 



(2I3) = 2a 



rr 0-0656 molar. 



h 



Q 



c 



X 



(2I3) 



(21) 



K, 



20-35 



353-6 



610 



0-580 



19-77 



45-8 



0-00134 



14-24 



220-8 



585 



0-3773 



13-86 



51-7 



0-00141 



9-76 



139-2 



580 



0-2399 



9-52 



56-1 



0-00141 



6-59 



87-8 



578 



0-1520 



6-44 



59-2 



0-00140 



5-85 



78-2 



578 



0-1353 



5-71 



59-9 



0-00142 



3-341 



41-67 



578 



0-0721 



3-269 



62-3 



0-00138 



1-758 



22-24 



578 



0-03849 



1-720 



63-9 



0-00143 











mean 



0-00139. 



After each determination, to continue the series, a volume 

 of the original halide solution equal to that removed from the 

 water layer, and a volume of the pure bisulphide or tetrachlor- 

 ide equal to that taken from the non-aqueous layer, were placed 

 ill the bottle and the whole process repeated as before. 



A few of the determinations of A'^, as is indicated in the tables, 

 were made in solutions satui^ated with iodine, using no carbon 



