182 Moody — lodometric Determination of Aluminium. 



charged with a solution of potassium iodide. The iodine col- 

 lected was titrated with — sodium thiosulphate. 



Table I gives results obtained by this method. The details 

 of the experiments in which steam was used as an agent to 

 force the iodine over are given in section A, while those of the 

 experiments in which hydrogen was employed are indicated in 

 section B. 



Table I. 



Approx. — 















Aluminium 

 chloride 



HIOs. 



KI. 



Time in 



A U 



Approx. ^ 



A1 2 3 

 calculated 



Diff. 



solution. 



grm. 



grm. 



minutes. 



Na 2 S 2 3 . 



grm. 



grm. 



cm 3 . 







A 



cm 3 . 







25 



0-3 



1-0 



25 



25*05 



0-0427 



— 0-0007 



25 



0*3 



1-0 



90 



25*15 



0-0428 



—o-oooo 



25 



0-3 



1-0 



20 



25-05 



0-0427 



— 0-0007 



25 



0-3 



1-0 



15 



25-10 



0*0428 



— 0-0006 



25 



0-3 



1-0 



15 



25-00* 



0-0426 



— 0-0009 



25 



0-3 



1-0 



• 15 



25-00* 



0-0426 



— 0-0009 



In each of these experiments the iodide-iodate mixture was 

 made by exactly neutralizing iodic acid with potassium hy- 

 droxide, adding a minute crystal of the iodic acid, introducing 

 the potassium iodide in solution and taking up with a drop or 

 two of sodium thiosulphate the iodine set free. This mixture 

 was put into the Voit flask together with the aluminium chlor- 

 ide, and the whole was heated in the current of steam or 

 hydrogen. 



Applying the process to a solution of potassium alum the 

 results recorded in the following table were obtained. 



Table II. 



A n 



Approx. — 

 Aluminium 



KI0 3 . 



KI 



Time in 



A n 



Approx. — 



A1 2 3 

 calcu- 



A1 2 3 



Diff. 



potassium 



grm. 



grm. 



minutes. 



Na 2 S 2 3 . 



lated. 



found. 



grm. 



alum. 









cm 3 . 



grm. 



grm. 





cm 3 . 

















25 



0-3 



1-0 



30 



24-55 



0-0410 



0-0414 



— 0-0004 



25 



0-3 



1-0 



30 



24-60 



0-0411 



0-0416 



— 0-0005 



25 



0-3 



1-0 



25 



24-50 



0-0409 



0-0414 



— 0-0005 



25 



0-3 



1-0 



30 



24-70 



0-0413 



0-0416 



— 0-0003 



25 



0-3 



1-0 



35 



24-50 



0-0409 



0-0415 



— 0-0006 



25 



0-3 



1-0 



30 



24-55 



0-0410 



0-0415 



— 0-0005 



25 ■ 



0-3 



1-0 



25 



24-50 



0-0409 



0-0415 



— 0-0006 



*New standard. 



