THE 



AMERICAN JOURNALOFSCIENCE 



[FOURTH SERIES.] 



Art. I. — An Iodine Titration Voltameter / by D. Albert 



Kreider. 



The rapidity, accuracy and sharpness of the end reaction 

 of several of the methods of volumetric analysis, particularly 

 of the iodometric methods, have suggested the possibility of 

 applying them to the voltameter. A rather extensive investi- 

 gation of quantitative electrolytic oxidation and reduction 

 methods, with this aim in view, has resulted in the evolution 

 of a titration voltameter the accuracy of which may be 

 depended upon to about one part in ten thousand. The 

 advantages in point of manipulation and time required, as well 

 as its applicability to a greater range of current density, will, 

 in the writer's opinion, make it of service in many investi- 

 gations. 



The basis of the method is the electrolysis of potassium 

 iodide and the titration of the liberated iodine by sodium thio- 

 sulphate. Herroun* first' suggested the use of iodine in this 

 connection. He electrolyzed zinc iodide between a platinum 

 anode and zinc cathode in a beaker ; but gives the results of 

 only one determination and leaves the method in an imprac- 

 ticable form. ' 



Danneelf reports four comparative tests of Herroun's zinc 

 iodide voltameter in series with a silver voltameter. The results 

 show a difference of between +0*27 per cent and —1 per cent. 

 His burette readings were made to only the nearest 0'1 CC , and the 

 total quantity of thiosulphate was small; varying from 7* to 34 ,cc . 



The work of Danneel, as well as that of Kistiakowsky^; on 

 a silver titration voltameter, seems never to have found its way 



* Phil. Mag. [5], xl, 91, 1895. 



f Zeitschr. fur Elect. Chem., iv, 154, 1897. 



% Zeitschr. Phys. Chem., vi, 97, 1890. 



Am. Jour. Sci.— Fourth Series, Vol. XX. No. 115.— July, 1905. 



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