328 Intelligence and Miscellaneous Articles. 



ON THE ACTION OF THE ELECTRIC CURRENT ON AQUEOUS SOLU- 

 TIONS OF CHLORINE, BROMINE, AND IODINE. BY JM. A. RICHE. 



On passing an electric current through a solution uf chlorine pre- 

 pared in the dark with boiled distilled water, two kinds of phaeno- 

 mena are observed. The first effect of the current, like that of 

 light and heat, is to decompose the water, whereby the oxygen 

 escapes, and the nascent hydrogen recombines with the excess of 

 chlorine, forming hydrochloric acid. Soon, however, the opposite 

 effect is produced, that is, the nascent hydrogen escapes in the free 

 state, while the nascent oxygen combines with the chlorine present. 



Thus with ten of Bunsen's elements, the volume of free oxygen 

 after the first eleven minutes was about double that of the hydrogen. 

 In about an hour the whole quantity of the gases liberated were 

 nearly equal, showing that the hydrogen was gaining on the oxygen. 

 In an hour and fifty minutes after the commencement, equal volumes 

 of hydrogen and oxygen were liberated in fifty-three and eighty-nine 

 minutes respectively. After four hours twenty-six minutes, the 

 times for the liberation of equal volumes were thirty-four minutes 

 for hydrogen and 182 for oxygen. 



At this point the absorption of the oxygen was at its maximum ; 

 it commenced diminishing until the liberated oxygen was exactly 

 half that of the hydrogen. 



The oxygen absorbed forms perchloric acid with the chlorine. 

 M. Riche explains this phsenomenon by supposing the water to be 

 first decomposed alone, and thereby free oxygen and hydrochloric 

 acid to be produced ; secondly, the so-formed hydrochloric acid to be 

 also decomposed simultaneously with the water, so that at the nega- 

 tive pole hydrogen is given off, while at the positive oxygen and chlo- 

 rine being liberated together, combine to form perchloric acid. He 

 supports this by showing that in chlorine water prepared twenty- 

 four hours previously, in very old chlorine water and in distilled 

 water acidulated with hydrochloric acid, the oxygen is absorbed from 

 the commencement. 



M. Riche recommends the above method for preparing perchloric 

 acid. 



Bromine, iodine, hydrobromic and hydriodic acids furnished very 

 analogous results, with the exception that with these the oxidation 

 ceases as soon as bromic and iodic acids are formed, the higher 

 degree of oxidation not being reached. 



In the same manner, bromide of potassium gives rise to bromate 

 of potash. 



If dry bromine and hydrogen be subjected together to the con- 

 tinued action of the electric spark, the two combine, and hydro- 

 bromic acid is formed. 



Dry chlorine and oxygen do not combine when subjected together 

 to the action of the electric spark ; but if moisture be present, the 

 chlorine is oxidized to perchloric acid. — Comptes Rendus de I' Acad, de 

 Scien., February 15, 1858. 



